[feat]: vulkan is going to be the end of me bro

4 files changed, 2105 insertions, 0 deletions

diff --git a/src/Platform/Vulkan/VulkanContext.cpp b/src/Platform/Vulkan/VulkanContext.cpp
new file mode 100644
index 0000000..9a67fe8
--- /dev/null
+++ b/src/Platform/Vulkan/VulkanContext.cpp
@@ -0,0 +1,789 @@
+#include "VulkanContext.h"
+#include "Core/Log.h"
+
+#include <vulkan/vulkan.h>
+
+#include <glm/glm.hpp>
+#include <glm/gtc/type_ptr.hpp>
+#include "stb_image_write.h"
+
+#include <vector>
+#include <cstring>
+#include <cstdlib>
+#include <fstream>
+
+namespace Donut
+{
+    // Logs and returns false from the enclosing function on any non-success result.
+    #define VK_CHECK(expr)                                                     \
+        do {                                                                   \
+            VkResult _r = (expr);                                              \
+            if (_r != VK_SUCCESS) {                                            \
+                DONUT_ERROR("Vulkan: {} failed ({})", #expr, (int)_r);         \
+                return false;                                                  \
+            }                                                                  \
+        } while (0)
+
+    struct VulkanContext::Impl
+    {
+        VkInstance       instance       = VK_NULL_HANDLE;
+        VkPhysicalDevice physical       = VK_NULL_HANDLE;
+        VkDevice         device         = VK_NULL_HANDLE;
+        VkQueue          graphicsQueue  = VK_NULL_HANDLE;
+        uint32_t         graphicsFamily = 0;
+        VkPhysicalDeviceMemoryProperties memProps{};
+
+        uint32_t FindMemoryType(uint32_t typeFilter, VkMemoryPropertyFlags flags) const
+        {
+            for (uint32_t i = 0; i < memProps.memoryTypeCount; ++i)
+                if ((typeFilter & (1u << i)) &&
+                    (memProps.memoryTypes[i].propertyFlags & flags) == flags)
+                    return i;
+            return UINT32_MAX;
+        }
+
+        bool CreateBuffer(VkDeviceSize size, VkBufferUsageFlags usage, VkMemoryPropertyFlags props,
+                          VkBuffer& buf, VkDeviceMemory& mem) const
+        {
+            VkBufferCreateInfo bci{ VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO };
+            bci.size = size; bci.usage = usage; bci.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
+            if (vkCreateBuffer(device, &bci, nullptr, &buf) != VK_SUCCESS) return false;
+            VkMemoryRequirements req{}; vkGetBufferMemoryRequirements(device, buf, &req);
+            VkMemoryAllocateInfo ai{ VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO };
+            ai.allocationSize = req.size;
+            ai.memoryTypeIndex = FindMemoryType(req.memoryTypeBits, props);
+            if (vkAllocateMemory(device, &ai, nullptr, &mem) != VK_SUCCESS) return false;
+            vkBindBufferMemory(device, buf, mem, 0);
+            return true;
+        }
+    };
+
+    VulkanContext::VulkanContext()  { m_Impl = new Impl(); }
+    VulkanContext::~VulkanContext() { Shutdown(); delete m_Impl; m_Impl = nullptr; }
+
+    bool VulkanContext::Init()
+    {
+        Impl& v = *m_Impl;
+
+#ifdef __APPLE__
+        // The Homebrew Vulkan loader does not auto-discover MoltenVK or the
+        // validation layers; point it at both unless already configured.
+        if (!getenv("VK_ICD_FILENAMES"))
+            setenv("VK_ICD_FILENAMES", "/opt/homebrew/etc/vulkan/icd.d/MoltenVK_icd.json", 0);
+        if (!getenv("VK_LAYER_PATH"))
+            setenv("VK_LAYER_PATH", "/opt/homebrew/share/vulkan/explicit_layer.d", 0);
+#endif
+
+        // Instance
+        VkApplicationInfo app{ VK_STRUCTURE_TYPE_APPLICATION_INFO };
+        app.pApplicationName = "Donut";
+        app.apiVersion       = VK_API_VERSION_1_2;
+
+        // MoltenVK is a portability driver: without the portability-enumeration
+        // extension + flag, vkEnumeratePhysicalDevices returns zero devices.
+        std::vector<const char*> exts = {
+            VK_KHR_PORTABILITY_ENUMERATION_EXTENSION_NAME,
+            VK_KHR_GET_PHYSICAL_DEVICE_PROPERTIES_2_EXTENSION_NAME,
+        };
+
+        // Enable validation layers when they are installed (optional).
+        std::vector<const char*> layers;
+        uint32_t layerCount = 0;
+        vkEnumerateInstanceLayerProperties(&layerCount, nullptr);
+        std::vector<VkLayerProperties> avail(layerCount);
+        vkEnumerateInstanceLayerProperties(&layerCount, avail.data());
+        for (const auto& l : avail)
+            if (std::strcmp(l.layerName, "VK_LAYER_KHRONOS_validation") == 0)
+                layers.push_back("VK_LAYER_KHRONOS_validation");
+
+        VkInstanceCreateInfo ici{ VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO };
+        ici.flags                   = VK_INSTANCE_CREATE_ENUMERATE_PORTABILITY_BIT_KHR;
+        ici.pApplicationInfo        = &app;
+        ici.enabledExtensionCount   = (uint32_t)exts.size();
+        ici.ppEnabledExtensionNames = exts.data();
+        ici.enabledLayerCount       = (uint32_t)layers.size();
+        ici.ppEnabledLayerNames     = layers.data();
+        VK_CHECK(vkCreateInstance(&ici, nullptr, &v.instance));
+
+        // Physical device
+        uint32_t deviceCount = 0;
+        vkEnumeratePhysicalDevices(v.instance, &deviceCount, nullptr);
+        if (deviceCount == 0) { DONUT_ERROR("Vulkan: no physical devices"); return false; }
+        std::vector<VkPhysicalDevice> devices(deviceCount);
+        vkEnumeratePhysicalDevices(v.instance, &deviceCount, devices.data());
+        v.physical = devices[0];
+
+        VkPhysicalDeviceProperties props{};
+        vkGetPhysicalDeviceProperties(v.physical, &props);
+        vkGetPhysicalDeviceMemoryProperties(v.physical, &v.memProps);
+
+        // Graphics queue family
+        uint32_t qCount = 0;
+        vkGetPhysicalDeviceQueueFamilyProperties(v.physical, &qCount, nullptr);
+        std::vector<VkQueueFamilyProperties> qfams(qCount);
+        vkGetPhysicalDeviceQueueFamilyProperties(v.physical, &qCount, qfams.data());
+        bool found = false;
+        for (uint32_t i = 0; i < qCount; ++i)
+            if (qfams[i].queueFlags & VK_QUEUE_GRAPHICS_BIT) { v.graphicsFamily = i; found = true; break; }
+        if (!found) { DONUT_ERROR("Vulkan: no graphics queue family"); return false; }
+
+        // Logical device
+        // MoltenVK requires VK_KHR_portability_subset to be enabled if present.
+        std::vector<const char*> devExts;
+        uint32_t devExtCount = 0;
+        vkEnumerateDeviceExtensionProperties(v.physical, nullptr, &devExtCount, nullptr);
+        std::vector<VkExtensionProperties> devExtProps(devExtCount);
+        vkEnumerateDeviceExtensionProperties(v.physical, nullptr, &devExtCount, devExtProps.data());
+        for (const auto& e : devExtProps)
+            if (std::strcmp(e.extensionName, "VK_KHR_portability_subset") == 0)
+                devExts.push_back("VK_KHR_portability_subset");
+
+        float priority = 1.0f;
+        VkDeviceQueueCreateInfo qci{ VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO };
+        qci.queueFamilyIndex = v.graphicsFamily;
+        qci.queueCount       = 1;
+        qci.pQueuePriorities = &priority;
+
+        VkDeviceCreateInfo dci{ VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO };
+        dci.queueCreateInfoCount    = 1;
+        dci.pQueueCreateInfos       = &qci;
+        dci.enabledExtensionCount   = (uint32_t)devExts.size();
+        dci.ppEnabledExtensionNames = devExts.data();
+        VK_CHECK(vkCreateDevice(v.physical, &dci, nullptr, &v.device));
+        vkGetDeviceQueue(v.device, v.graphicsFamily, 0, &v.graphicsQueue);
+
+        DONUT_INFO("Vulkan device: {} (API {}.{}.{}, validation {})",
+                   props.deviceName,
+                   VK_API_VERSION_MAJOR(props.apiVersion),
+                   VK_API_VERSION_MINOR(props.apiVersion),
+                   VK_API_VERSION_PATCH(props.apiVersion),
+                   layers.empty() ? "off" : "on");
+        return true;
+    }
+
+    bool VulkanContext::SelfTestClear()
+    {
+        Impl& v = *m_Impl;
+        if (v.device == VK_NULL_HANDLE) return false;
+
+        const uint32_t W = 64, H = 64;
+        const VkFormat fmt = VK_FORMAT_R8G8B8A8_UNORM;
+
+        // Offscreen colour image
+        VkImage image = VK_NULL_HANDLE; VkDeviceMemory imageMem = VK_NULL_HANDLE;
+        VkImageCreateInfo ici{ VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO };
+        ici.imageType   = VK_IMAGE_TYPE_2D;
+        ici.format      = fmt;
+        ici.extent      = { W, H, 1 };
+        ici.mipLevels   = 1;
+        ici.arrayLayers = 1;
+        ici.samples     = VK_SAMPLE_COUNT_1_BIT;
+        ici.tiling      = VK_IMAGE_TILING_OPTIMAL;
+        ici.usage       = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT | VK_IMAGE_USAGE_TRANSFER_SRC_BIT;
+        ici.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
+        VK_CHECK(vkCreateImage(v.device, &ici, nullptr, &image));
+
+        VkMemoryRequirements imReq{};
+        vkGetImageMemoryRequirements(v.device, image, &imReq);
+        VkMemoryAllocateInfo imAlloc{ VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO };
+        imAlloc.allocationSize  = imReq.size;
+        imAlloc.memoryTypeIndex = v.FindMemoryType(imReq.memoryTypeBits, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);
+        VK_CHECK(vkAllocateMemory(v.device, &imAlloc, nullptr, &imageMem));
+        VK_CHECK(vkBindImageMemory(v.device, image, imageMem, 0));
+
+        VkImageView view = VK_NULL_HANDLE;
+        VkImageViewCreateInfo vci{ VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO };
+        vci.image    = image;
+        vci.viewType = VK_IMAGE_VIEW_TYPE_2D;
+        vci.format   = fmt;
+        vci.subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1 };
+        VK_CHECK(vkCreateImageView(v.device, &vci, nullptr, &view));
+
+        // Render pass (clear -> store, leave in TRANSFER_SRC for readback)
+        VkAttachmentDescription color{};
+        color.format         = fmt;
+        color.samples        = VK_SAMPLE_COUNT_1_BIT;
+        color.loadOp         = VK_ATTACHMENT_LOAD_OP_CLEAR;
+        color.storeOp        = VK_ATTACHMENT_STORE_OP_STORE;
+        color.stencilLoadOp  = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
+        color.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
+        color.initialLayout  = VK_IMAGE_LAYOUT_UNDEFINED;
+        color.finalLayout    = VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL;
+
+        VkAttachmentReference colorRef{ 0, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL };
+        VkSubpassDescription subpass{};
+        subpass.pipelineBindPoint    = VK_PIPELINE_BIND_POINT_GRAPHICS;
+        subpass.colorAttachmentCount = 1;
+        subpass.pColorAttachments    = &colorRef;
+
+        // Ensure colour writes finish before the read-back copy.
+        VkSubpassDependency dep{};
+        dep.srcSubpass    = 0;
+        dep.dstSubpass    = VK_SUBPASS_EXTERNAL;
+        dep.srcStageMask  = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
+        dep.srcAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
+        dep.dstStageMask  = VK_PIPELINE_STAGE_TRANSFER_BIT;
+        dep.dstAccessMask = VK_ACCESS_TRANSFER_READ_BIT;
+
+        VkRenderPass renderPass = VK_NULL_HANDLE;
+        VkRenderPassCreateInfo rpci{ VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO };
+        rpci.attachmentCount = 1; rpci.pAttachments = &color;
+        rpci.subpassCount    = 1; rpci.pSubpasses   = &subpass;
+        rpci.dependencyCount = 1; rpci.pDependencies = &dep;
+        VK_CHECK(vkCreateRenderPass(v.device, &rpci, nullptr, &renderPass));
+
+        VkFramebuffer fb = VK_NULL_HANDLE;
+        VkFramebufferCreateInfo fbci{ VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO };
+        fbci.renderPass = renderPass;
+        fbci.attachmentCount = 1; fbci.pAttachments = &view;
+        fbci.width = W; fbci.height = H; fbci.layers = 1;
+        VK_CHECK(vkCreateFramebuffer(v.device, &fbci, nullptr, &fb));
+
+        // Host-visible staging buffer for read-back
+        VkBuffer staging = VK_NULL_HANDLE; VkDeviceMemory stagingMem = VK_NULL_HANDLE;
+        VkBufferCreateInfo bci{ VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO };
+        bci.size  = (VkDeviceSize)W * H * 4;
+        bci.usage = VK_BUFFER_USAGE_TRANSFER_DST_BIT;
+        bci.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
+        VK_CHECK(vkCreateBuffer(v.device, &bci, nullptr, &staging));
+        VkMemoryRequirements bReq{};
+        vkGetBufferMemoryRequirements(v.device, staging, &bReq);
+        VkMemoryAllocateInfo bAlloc{ VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO };
+        bAlloc.allocationSize  = bReq.size;
+        bAlloc.memoryTypeIndex = v.FindMemoryType(bReq.memoryTypeBits,
+            VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT);
+        VK_CHECK(vkAllocateMemory(v.device, &bAlloc, nullptr, &stagingMem));
+        VK_CHECK(vkBindBufferMemory(v.device, staging, stagingMem, 0));
+
+        // Command buffer: clear via render pass, then copy image -> buffer
+        VkCommandPool pool = VK_NULL_HANDLE;
+        VkCommandPoolCreateInfo pci{ VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO };
+        pci.queueFamilyIndex = v.graphicsFamily;
+        VK_CHECK(vkCreateCommandPool(v.device, &pci, nullptr, &pool));
+
+        VkCommandBuffer cmd = VK_NULL_HANDLE;
+        VkCommandBufferAllocateInfo cbai{ VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO };
+        cbai.commandPool = pool; cbai.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY; cbai.commandBufferCount = 1;
+        VK_CHECK(vkAllocateCommandBuffers(v.device, &cbai, &cmd));
+
+        VkCommandBufferBeginInfo begin{ VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO };
+        begin.flags = VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT;
+        VK_CHECK(vkBeginCommandBuffer(cmd, &begin));
+
+        VkClearValue clear{};
+        clear.color = { { 0.2f, 0.4f, 0.8f, 1.0f } };   // -> RGBA8 (51, 102, 204, 255)
+        VkRenderPassBeginInfo rpbi{ VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO };
+        rpbi.renderPass = renderPass; rpbi.framebuffer = fb;
+        rpbi.renderArea = { { 0, 0 }, { W, H } };
+        rpbi.clearValueCount = 1; rpbi.pClearValues = &clear;
+        vkCmdBeginRenderPass(cmd, &rpbi, VK_SUBPASS_CONTENTS_INLINE);
+        vkCmdEndRenderPass(cmd);
+
+        VkBufferImageCopy region{};
+        region.imageSubresource = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 0, 1 };
+        region.imageExtent      = { W, H, 1 };
+        vkCmdCopyImageToBuffer(cmd, image, VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL, staging, 1, &region);
+        VK_CHECK(vkEndCommandBuffer(cmd));
+
+        VkFence fence = VK_NULL_HANDLE;
+        VkFenceCreateInfo fci{ VK_STRUCTURE_TYPE_FENCE_CREATE_INFO };
+        VK_CHECK(vkCreateFence(v.device, &fci, nullptr, &fence));
+        VkSubmitInfo submit{ VK_STRUCTURE_TYPE_SUBMIT_INFO };
+        submit.commandBufferCount = 1; submit.pCommandBuffers = &cmd;
+        VK_CHECK(vkQueueSubmit(v.graphicsQueue, 1, &submit, fence));
+        VK_CHECK(vkWaitForFences(v.device, 1, &fence, VK_TRUE, UINT64_MAX));
+
+        // Read back + verify
+        void* mapped = nullptr;
+        VK_CHECK(vkMapMemory(v.device, stagingMem, 0, bci.size, 0, &mapped));
+        const uint8_t* px = (const uint8_t*)mapped;
+        DONUT_INFO("Vulkan clear self-test: pixel RGBA = ({}, {}, {}, {})",
+                   (int)px[0], (int)px[1], (int)px[2], (int)px[3]);
+        bool ok = px[0] > 45 && px[0] < 60 && px[1] > 95 && px[1] < 110 &&
+                  px[2] > 195 && px[2] < 210 && px[3] == 255;
+        vkUnmapMemory(v.device, stagingMem);
+        DONUT_INFO("Vulkan clear self-test: {}", ok ? "PASS" : "FAIL");
+
+        // Cleanup
+        vkDestroyFence(v.device, fence, nullptr);
+        vkDestroyCommandPool(v.device, pool, nullptr);
+        vkDestroyBuffer(v.device, staging, nullptr);
+        vkFreeMemory(v.device, stagingMem, nullptr);
+        vkDestroyFramebuffer(v.device, fb, nullptr);
+        vkDestroyRenderPass(v.device, renderPass, nullptr);
+        vkDestroyImageView(v.device, view, nullptr);
+        vkDestroyImage(v.device, image, nullptr);
+        vkFreeMemory(v.device, imageMem, nullptr);
+        return ok;
+    }
+
+    static std::vector<uint32_t> LoadSpirv(const std::string& path)
+    {
+        std::ifstream f(path, std::ios::binary | std::ios::ate);
+        if (!f) return {};
+        size_t size = (size_t)f.tellg();
+        std::vector<uint32_t> data(size / 4);
+        f.seekg(0);
+        f.read((char*)data.data(), (std::streamsize)size);
+        return data;
+    }
+
+    bool VulkanContext::SelfTestTriangle()
+    {
+        Impl& v = *m_Impl;
+        if (v.device == VK_NULL_HANDLE) return false;
+
+        const uint32_t W = 64, H = 64;
+        const VkFormat fmt = VK_FORMAT_R8G8B8A8_UNORM;
+
+        // Offscreen image + view (as in the clear test)
+        VkImage image = VK_NULL_HANDLE; VkDeviceMemory imageMem = VK_NULL_HANDLE;
+        VkImageCreateInfo ici{ VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO };
+        ici.imageType = VK_IMAGE_TYPE_2D; ici.format = fmt; ici.extent = { W, H, 1 };
+        ici.mipLevels = 1; ici.arrayLayers = 1; ici.samples = VK_SAMPLE_COUNT_1_BIT;
+        ici.tiling = VK_IMAGE_TILING_OPTIMAL;
+        ici.usage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT | VK_IMAGE_USAGE_TRANSFER_SRC_BIT;
+        VK_CHECK(vkCreateImage(v.device, &ici, nullptr, &image));
+        VkMemoryRequirements imReq{}; vkGetImageMemoryRequirements(v.device, image, &imReq);
+        VkMemoryAllocateInfo imAlloc{ VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO };
+        imAlloc.allocationSize = imReq.size;
+        imAlloc.memoryTypeIndex = v.FindMemoryType(imReq.memoryTypeBits, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);
+        VK_CHECK(vkAllocateMemory(v.device, &imAlloc, nullptr, &imageMem));
+        VK_CHECK(vkBindImageMemory(v.device, image, imageMem, 0));
+        VkImageView view = VK_NULL_HANDLE;
+        VkImageViewCreateInfo vci{ VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO };
+        vci.image = image; vci.viewType = VK_IMAGE_VIEW_TYPE_2D; vci.format = fmt;
+        vci.subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1 };
+        VK_CHECK(vkCreateImageView(v.device, &vci, nullptr, &view));
+
+        // Render pass + framebuffer
+        VkAttachmentDescription color{};
+        color.format = fmt; color.samples = VK_SAMPLE_COUNT_1_BIT;
+        color.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR; color.storeOp = VK_ATTACHMENT_STORE_OP_STORE;
+        color.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE; color.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
+        color.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED; color.finalLayout = VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL;
+        VkAttachmentReference colorRef{ 0, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL };
+        VkSubpassDescription subpass{};
+        subpass.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
+        subpass.colorAttachmentCount = 1; subpass.pColorAttachments = &colorRef;
+        VkSubpassDependency dep{};
+        dep.srcSubpass = 0; dep.dstSubpass = VK_SUBPASS_EXTERNAL;
+        dep.srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT; dep.srcAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
+        dep.dstStageMask = VK_PIPELINE_STAGE_TRANSFER_BIT; dep.dstAccessMask = VK_ACCESS_TRANSFER_READ_BIT;
+        VkRenderPass renderPass = VK_NULL_HANDLE;
+        VkRenderPassCreateInfo rpci{ VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO };
+        rpci.attachmentCount = 1; rpci.pAttachments = &color;
+        rpci.subpassCount = 1; rpci.pSubpasses = &subpass;
+        rpci.dependencyCount = 1; rpci.pDependencies = &dep;
+        VK_CHECK(vkCreateRenderPass(v.device, &rpci, nullptr, &renderPass));
+        VkFramebuffer fb = VK_NULL_HANDLE;
+        VkFramebufferCreateInfo fbci{ VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO };
+        fbci.renderPass = renderPass; fbci.attachmentCount = 1; fbci.pAttachments = &view;
+        fbci.width = W; fbci.height = H; fbci.layers = 1;
+        VK_CHECK(vkCreateFramebuffer(v.device, &fbci, nullptr, &fb));
+
+        // Shader modules from Slang SPIR-V
+        auto vspv = LoadSpirv("Assets/Shaders/generated/VkPipelineTest.vertexMain.spv");
+        auto fspv = LoadSpirv("Assets/Shaders/generated/VkPipelineTest.fragmentMain.spv");
+        if (vspv.empty() || fspv.empty()) { DONUT_ERROR("Vulkan: VkPipelineTest SPIR-V not found"); return false; }
+        VkShaderModule vmod = VK_NULL_HANDLE, fmod = VK_NULL_HANDLE;
+        VkShaderModuleCreateInfo smci{ VK_STRUCTURE_TYPE_SHADER_MODULE_CREATE_INFO };
+        smci.codeSize = vspv.size() * 4; smci.pCode = vspv.data();
+        VK_CHECK(vkCreateShaderModule(v.device, &smci, nullptr, &vmod));
+        smci.codeSize = fspv.size() * 4; smci.pCode = fspv.data();
+        VK_CHECK(vkCreateShaderModule(v.device, &smci, nullptr, &fmod));
+
+        // Graphics pipeline
+        VkPipelineShaderStageCreateInfo stages[2]{};
+        stages[0].sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
+        stages[0].stage = VK_SHADER_STAGE_VERTEX_BIT;   stages[0].module = vmod; stages[0].pName = "main";
+        stages[1].sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO;
+        stages[1].stage = VK_SHADER_STAGE_FRAGMENT_BIT; stages[1].module = fmod; stages[1].pName = "main";
+
+        VkPipelineVertexInputStateCreateInfo vin{ VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO };
+        VkPipelineInputAssemblyStateCreateInfo ia{ VK_STRUCTURE_TYPE_PIPELINE_INPUT_ASSEMBLY_STATE_CREATE_INFO };
+        ia.topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;
+        VkViewport vp{ 0, 0, (float)W, (float)H, 0, 1 };
+        VkRect2D scissor{ { 0, 0 }, { W, H } };
+        VkPipelineViewportStateCreateInfo vps{ VK_STRUCTURE_TYPE_PIPELINE_VIEWPORT_STATE_CREATE_INFO };
+        vps.viewportCount = 1; vps.pViewports = &vp; vps.scissorCount = 1; vps.pScissors = &scissor;
+        VkPipelineRasterizationStateCreateInfo rs{ VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_STATE_CREATE_INFO };
+        rs.polygonMode = VK_POLYGON_MODE_FILL; rs.cullMode = VK_CULL_MODE_NONE; rs.frontFace = VK_FRONT_FACE_COUNTER_CLOCKWISE; rs.lineWidth = 1.0f;
+        VkPipelineMultisampleStateCreateInfo ms{ VK_STRUCTURE_TYPE_PIPELINE_MULTISAMPLE_STATE_CREATE_INFO };
+        ms.rasterizationSamples = VK_SAMPLE_COUNT_1_BIT;
+        VkPipelineColorBlendAttachmentState cba{};
+        cba.colorWriteMask = VK_COLOR_COMPONENT_R_BIT | VK_COLOR_COMPONENT_G_BIT | VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT;
+        VkPipelineColorBlendStateCreateInfo cb{ VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO };
+        cb.attachmentCount = 1; cb.pAttachments = &cba;
+
+        VkPipelineLayout layout = VK_NULL_HANDLE;
+        VkPipelineLayoutCreateInfo plci{ VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO };
+        VK_CHECK(vkCreatePipelineLayout(v.device, &plci, nullptr, &layout));
+
+        VkPipeline pipeline = VK_NULL_HANDLE;
+        VkGraphicsPipelineCreateInfo gpci{ VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO };
+        gpci.stageCount = 2; gpci.pStages = stages;
+        gpci.pVertexInputState = &vin; gpci.pInputAssemblyState = &ia;
+        gpci.pViewportState = &vps; gpci.pRasterizationState = &rs;
+        gpci.pMultisampleState = &ms; gpci.pColorBlendState = &cb;
+        gpci.layout = layout; gpci.renderPass = renderPass; gpci.subpass = 0;
+        VK_CHECK(vkCreateGraphicsPipelines(v.device, VK_NULL_HANDLE, 1, &gpci, nullptr, &pipeline));
+
+        // Readback staging buffer
+        VkBuffer staging = VK_NULL_HANDLE; VkDeviceMemory stagingMem = VK_NULL_HANDLE;
+        VkBufferCreateInfo bci{ VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO };
+        bci.size = (VkDeviceSize)W * H * 4; bci.usage = VK_BUFFER_USAGE_TRANSFER_DST_BIT;
+        VK_CHECK(vkCreateBuffer(v.device, &bci, nullptr, &staging));
+        VkMemoryRequirements bReq{}; vkGetBufferMemoryRequirements(v.device, staging, &bReq);
+        VkMemoryAllocateInfo bAlloc{ VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO };
+        bAlloc.allocationSize = bReq.size;
+        bAlloc.memoryTypeIndex = v.FindMemoryType(bReq.memoryTypeBits, VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT);
+        VK_CHECK(vkAllocateMemory(v.device, &bAlloc, nullptr, &stagingMem));
+        VK_CHECK(vkBindBufferMemory(v.device, staging, stagingMem, 0));
+
+        // Record + submit
+        VkCommandPool pool = VK_NULL_HANDLE;
+        VkCommandPoolCreateInfo pci{ VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO };
+        pci.queueFamilyIndex = v.graphicsFamily;
+        VK_CHECK(vkCreateCommandPool(v.device, &pci, nullptr, &pool));
+        VkCommandBuffer cmd = VK_NULL_HANDLE;
+        VkCommandBufferAllocateInfo cbai{ VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO };
+        cbai.commandPool = pool; cbai.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY; cbai.commandBufferCount = 1;
+        VK_CHECK(vkAllocateCommandBuffers(v.device, &cbai, &cmd));
+        VkCommandBufferBeginInfo begin{ VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO };
+        begin.flags = VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT;
+        VK_CHECK(vkBeginCommandBuffer(cmd, &begin));
+        VkClearValue clear{}; clear.color = { { 0.0f, 0.0f, 0.0f, 1.0f } };
+        VkRenderPassBeginInfo rpbi{ VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO };
+        rpbi.renderPass = renderPass; rpbi.framebuffer = fb;
+        rpbi.renderArea = { { 0, 0 }, { W, H } };
+        rpbi.clearValueCount = 1; rpbi.pClearValues = &clear;
+        vkCmdBeginRenderPass(cmd, &rpbi, VK_SUBPASS_CONTENTS_INLINE);
+        vkCmdBindPipeline(cmd, VK_PIPELINE_BIND_POINT_GRAPHICS, pipeline);
+        vkCmdDraw(cmd, 3, 1, 0, 0);
+        vkCmdEndRenderPass(cmd);
+        VkBufferImageCopy region{};
+        region.imageSubresource = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 0, 1 };
+        region.imageExtent = { W, H, 1 };
+        vkCmdCopyImageToBuffer(cmd, image, VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL, staging, 1, &region);
+        VK_CHECK(vkEndCommandBuffer(cmd));
+
+        VkFence fence = VK_NULL_HANDLE;
+        VkFenceCreateInfo fci{ VK_STRUCTURE_TYPE_FENCE_CREATE_INFO };
+        VK_CHECK(vkCreateFence(v.device, &fci, nullptr, &fence));
+        VkSubmitInfo submit{ VK_STRUCTURE_TYPE_SUBMIT_INFO };
+        submit.commandBufferCount = 1; submit.pCommandBuffers = &cmd;
+        VK_CHECK(vkQueueSubmit(v.graphicsQueue, 1, &submit, fence));
+        VK_CHECK(vkWaitForFences(v.device, 1, &fence, VK_TRUE, UINT64_MAX));
+
+        // Verify: centre pixel should be the mid-gradient (not black)
+        void* mapped = nullptr;
+        VK_CHECK(vkMapMemory(v.device, stagingMem, 0, bci.size, 0, &mapped));
+        const uint8_t* px = (const uint8_t*)mapped;
+        size_t c = ((size_t)(H / 2) * W + (W / 2)) * 4;
+        DONUT_INFO("Vulkan triangle self-test: centre pixel RGBA = ({}, {}, {}, {})",
+                   (int)px[c + 0], (int)px[c + 1], (int)px[c + 2], (int)px[c + 3]);
+        bool ok = (px[c + 0] > 40 || px[c + 1] > 40) && px[c + 3] == 255;
+        vkUnmapMemory(v.device, stagingMem);
+        DONUT_INFO("Vulkan triangle self-test: {}", ok ? "PASS" : "FAIL");
+
+        // Cleanup
+        vkDestroyFence(v.device, fence, nullptr);
+        vkDestroyCommandPool(v.device, pool, nullptr);
+        vkDestroyBuffer(v.device, staging, nullptr);
+        vkFreeMemory(v.device, stagingMem, nullptr);
+        vkDestroyPipeline(v.device, pipeline, nullptr);
+        vkDestroyPipelineLayout(v.device, layout, nullptr);
+        vkDestroyShaderModule(v.device, vmod, nullptr);
+        vkDestroyShaderModule(v.device, fmod, nullptr);
+        vkDestroyFramebuffer(v.device, fb, nullptr);
+        vkDestroyRenderPass(v.device, renderPass, nullptr);
+        vkDestroyImageView(v.device, view, nullptr);
+        vkDestroyImage(v.device, image, nullptr);
+        vkFreeMemory(v.device, imageMem, nullptr);
+        return ok;
+    }
+
+    bool VulkanContext::RenderGeodesic(const char* pngPath)
+    {
+        Impl& v = *m_Impl;
+        if (v.device == VK_NULL_HANDLE) return false;
+
+        const uint32_t W = 384, H = 216;
+        const VkFormat fmt = VK_FORMAT_R8G8B8A8_UNORM;
+        const float SagA_rs = 1.269e10f;
+
+        // Offscreen colour target
+        VkImage image = VK_NULL_HANDLE; VkDeviceMemory imageMem = VK_NULL_HANDLE;
+        VkImageCreateInfo ici{ VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO };
+        ici.imageType = VK_IMAGE_TYPE_2D; ici.format = fmt; ici.extent = { W, H, 1 };
+        ici.mipLevels = 1; ici.arrayLayers = 1; ici.samples = VK_SAMPLE_COUNT_1_BIT;
+        ici.tiling = VK_IMAGE_TILING_OPTIMAL;
+        ici.usage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT | VK_IMAGE_USAGE_TRANSFER_SRC_BIT;
+        VK_CHECK(vkCreateImage(v.device, &ici, nullptr, &image));
+        VkMemoryRequirements imReq{}; vkGetImageMemoryRequirements(v.device, image, &imReq);
+        VkMemoryAllocateInfo imAlloc{ VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO };
+        imAlloc.allocationSize = imReq.size;
+        imAlloc.memoryTypeIndex = v.FindMemoryType(imReq.memoryTypeBits, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);
+        VK_CHECK(vkAllocateMemory(v.device, &imAlloc, nullptr, &imageMem));
+        VK_CHECK(vkBindImageMemory(v.device, image, imageMem, 0));
+        VkImageView view = VK_NULL_HANDLE;
+        VkImageViewCreateInfo vci{ VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO };
+        vci.image = image; vci.viewType = VK_IMAGE_VIEW_TYPE_2D; vci.format = fmt;
+        vci.subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1 };
+        VK_CHECK(vkCreateImageView(v.device, &vci, nullptr, &view));
+
+        VkAttachmentDescription color{};
+        color.format = fmt; color.samples = VK_SAMPLE_COUNT_1_BIT;
+        color.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR; color.storeOp = VK_ATTACHMENT_STORE_OP_STORE;
+        color.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE; color.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
+        color.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED; color.finalLayout = VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL;
+        VkAttachmentReference colorRef{ 0, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL };
+        VkSubpassDescription subpass{}; subpass.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
+        subpass.colorAttachmentCount = 1; subpass.pColorAttachments = &colorRef;
+        VkSubpassDependency dep{};
+        dep.srcSubpass = 0; dep.dstSubpass = VK_SUBPASS_EXTERNAL;
+        dep.srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT; dep.srcAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
+        dep.dstStageMask = VK_PIPELINE_STAGE_TRANSFER_BIT; dep.dstAccessMask = VK_ACCESS_TRANSFER_READ_BIT;
+        VkRenderPass renderPass = VK_NULL_HANDLE;
+        VkRenderPassCreateInfo rpci{ VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO };
+        rpci.attachmentCount = 1; rpci.pAttachments = &color;
+        rpci.subpassCount = 1; rpci.pSubpasses = &subpass;
+        rpci.dependencyCount = 1; rpci.pDependencies = &dep;
+        VK_CHECK(vkCreateRenderPass(v.device, &rpci, nullptr, &renderPass));
+        VkFramebuffer fb = VK_NULL_HANDLE;
+        VkFramebufferCreateInfo fbci{ VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO };
+        fbci.renderPass = renderPass; fbci.attachmentCount = 1; fbci.pAttachments = &view;
+        fbci.width = W; fbci.height = H; fbci.layers = 1;
+        VK_CHECK(vkCreateFramebuffer(v.device, &fbci, nullptr, &fb));
+
+        // Uniform buffers (host-visible), filled to match the shader's std140 layout
+        const VkMemoryPropertyFlags hostVis = VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT;
+        VkBuffer camBuf, diskBuf, objBuf, simBuf;
+        VkDeviceMemory camMem, diskMem, objMem, simMem;
+        v.CreateBuffer(128, VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT, hostVis, camBuf, camMem);
+        v.CreateBuffer(32,  VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT, hostVis, diskBuf, diskMem);
+        v.CreateBuffer(800, VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT, hostVis, objBuf, objMem);
+        v.CreateBuffer(16,  VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT, hostVis, simBuf, simMem);
+
+        struct CamUBO {
+            glm::vec3 pos; float p0; glm::vec3 right; float p1;
+            glm::vec3 up; float p2; glm::vec3 fwd; float p3;
+            float tanHalfFov; float aspect; uint32_t moving; int p4;
+        } cam{};
+        glm::vec3 camPos(1e11f, 0.32e11f, 0.0f);
+        glm::vec3 fwd = glm::normalize(glm::vec3(0.0f) - camPos);
+        glm::vec3 right = glm::normalize(glm::cross(fwd, glm::vec3(0, 1, 0)));
+        glm::vec3 up = glm::cross(right, fwd);
+        cam.pos = camPos; cam.right = right; cam.up = up; cam.fwd = fwd;
+        cam.tanHalfFov = 0.57735f; cam.aspect = (float)W / (float)H; cam.moving = 0;
+        void* p = nullptr;
+        vkMapMemory(v.device, camMem, 0, 128, 0, &p); memcpy(p, &cam, sizeof(cam)); vkUnmapMemory(v.device, camMem);
+
+        float disk[8] = { SagA_rs * 2.2f, SagA_rs * 5.2f, 2.0f, SagA_rs * 0.1f, 0.1f, 0, 0, 0 };
+        vkMapMemory(v.device, diskMem, 0, 32, 0, &p); memcpy(p, disk, sizeof(disk)); vkUnmapMemory(v.device, diskMem);
+
+        std::vector<uint8_t> objData(800, 0);
+        int numObjects = 1; memcpy(objData.data(), &numObjects, 4);
+        float posRadius[4] = { 0, 0, 0, SagA_rs }; memcpy(objData.data() + 16, posRadius, 16);
+        float objColor[4] = { 0, 0, 0, 1 };        memcpy(objData.data() + 272, objColor, 16);
+        vkMapMemory(v.device, objMem, 0, 800, 0, &p); memcpy(p, objData.data(), 800); vkUnmapMemory(v.device, objMem);
+
+        struct SimUBO { int stepsMoving; int stepsStatic; float earlyExit; float time; } sim{ 6000, 6000, 5e12f, 0.0f };
+        vkMapMemory(v.device, simMem, 0, 16, 0, &p); memcpy(p, &sim, sizeof(sim)); vkUnmapMemory(v.device, simMem);
+
+        // Dark cubemap (stands in for the HDRI for now)
+        VkImage cube = VK_NULL_HANDLE; VkDeviceMemory cubeMem = VK_NULL_HANDLE;
+        VkImageCreateInfo cci{ VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO };
+        cci.flags = VK_IMAGE_CREATE_CUBE_COMPATIBLE_BIT;
+        cci.imageType = VK_IMAGE_TYPE_2D; cci.format = fmt; cci.extent = { 1, 1, 1 };
+        cci.mipLevels = 1; cci.arrayLayers = 6; cci.samples = VK_SAMPLE_COUNT_1_BIT;
+        cci.tiling = VK_IMAGE_TILING_OPTIMAL;
+        cci.usage = VK_IMAGE_USAGE_TRANSFER_DST_BIT | VK_IMAGE_USAGE_SAMPLED_BIT;
+        VK_CHECK(vkCreateImage(v.device, &cci, nullptr, &cube));
+        VkMemoryRequirements cubeReq{}; vkGetImageMemoryRequirements(v.device, cube, &cubeReq);
+        VkMemoryAllocateInfo cubeAlloc{ VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO };
+        cubeAlloc.allocationSize = cubeReq.size;
+        cubeAlloc.memoryTypeIndex = v.FindMemoryType(cubeReq.memoryTypeBits, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);
+        VK_CHECK(vkAllocateMemory(v.device, &cubeAlloc, nullptr, &cubeMem));
+        VK_CHECK(vkBindImageMemory(v.device, cube, cubeMem, 0));
+        VkImageView cubeView = VK_NULL_HANDLE;
+        VkImageViewCreateInfo cvci{ VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO };
+        cvci.image = cube; cvci.viewType = VK_IMAGE_VIEW_TYPE_CUBE; cvci.format = fmt;
+        cvci.subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 6 };
+        VK_CHECK(vkCreateImageView(v.device, &cvci, nullptr, &cubeView));
+        VkSampler sampler = VK_NULL_HANDLE;
+        VkSamplerCreateInfo smci{ VK_STRUCTURE_TYPE_SAMPLER_CREATE_INFO };
+        smci.magFilter = VK_FILTER_LINEAR; smci.minFilter = VK_FILTER_LINEAR;
+        smci.addressModeU = smci.addressModeV = smci.addressModeW = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE;
+        VK_CHECK(vkCreateSampler(v.device, &smci, nullptr, &sampler));
+
+        VkBuffer cubeStaging; VkDeviceMemory cubeStagingMem;
+        v.CreateBuffer(6 * 4, VK_BUFFER_USAGE_TRANSFER_SRC_BIT, hostVis, cubeStaging, cubeStagingMem);
+        uint8_t cubePixels[6 * 4];
+        for (int i = 0; i < 6; ++i) { cubePixels[i * 4 + 0] = 6; cubePixels[i * 4 + 1] = 6; cubePixels[i * 4 + 2] = 14; cubePixels[i * 4 + 3] = 255; }
+        vkMapMemory(v.device, cubeStagingMem, 0, 24, 0, &p); memcpy(p, cubePixels, 24); vkUnmapMemory(v.device, cubeStagingMem);
+
+        // Descriptor set: 4 UBOs (bindings 0-3) + cubemap sampler (binding 4)
+        VkDescriptorSetLayoutBinding binds[5]{};
+        for (int i = 0; i < 4; ++i) { binds[i].binding = i; binds[i].descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER; binds[i].descriptorCount = 1; binds[i].stageFlags = VK_SHADER_STAGE_FRAGMENT_BIT; }
+        binds[4].binding = 4; binds[4].descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER; binds[4].descriptorCount = 1; binds[4].stageFlags = VK_SHADER_STAGE_FRAGMENT_BIT;
+        VkDescriptorSetLayout setLayout = VK_NULL_HANDLE;
+        VkDescriptorSetLayoutCreateInfo dslci{ VK_STRUCTURE_TYPE_DESCRIPTOR_SET_LAYOUT_CREATE_INFO };
+        dslci.bindingCount = 5; dslci.pBindings = binds;
+        VK_CHECK(vkCreateDescriptorSetLayout(v.device, &dslci, nullptr, &setLayout));
+        VkDescriptorPoolSize psizes[2] = { { VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, 4 }, { VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, 1 } };
+        VkDescriptorPool pool = VK_NULL_HANDLE;
+        VkDescriptorPoolCreateInfo dpci{ VK_STRUCTURE_TYPE_DESCRIPTOR_POOL_CREATE_INFO };
+        dpci.maxSets = 1; dpci.poolSizeCount = 2; dpci.pPoolSizes = psizes;
+        VK_CHECK(vkCreateDescriptorPool(v.device, &dpci, nullptr, &pool));
+        VkDescriptorSet set = VK_NULL_HANDLE;
+        VkDescriptorSetAllocateInfo dsai{ VK_STRUCTURE_TYPE_DESCRIPTOR_SET_ALLOCATE_INFO };
+        dsai.descriptorPool = pool; dsai.descriptorSetCount = 1; dsai.pSetLayouts = &setLayout;
+        VK_CHECK(vkAllocateDescriptorSets(v.device, &dsai, &set));
+
+        // Load geodesic SPIR-V + build the pipeline
+        auto vspv = LoadSpirv("Assets/Shaders/generated/Geodesic.vertexMain.spv");
+        auto fspv = LoadSpirv("Assets/Shaders/generated/Geodesic.fragmentMain.spv");
+        if (vspv.empty() || fspv.empty()) { DONUT_ERROR("Vulkan: geodesic SPIR-V not found"); return false; }
+        VkShaderModule vmod, fmod;
+        VkShaderModuleCreateInfo smci2{ VK_STRUCTURE_TYPE_SHADER_MODULE_CREATE_INFO };
+        smci2.codeSize = vspv.size() * 4; smci2.pCode = vspv.data(); VK_CHECK(vkCreateShaderModule(v.device, &smci2, nullptr, &vmod));
+        smci2.codeSize = fspv.size() * 4; smci2.pCode = fspv.data(); VK_CHECK(vkCreateShaderModule(v.device, &smci2, nullptr, &fmod));
+
+        VkPipelineLayout layout = VK_NULL_HANDLE;
+        VkPipelineLayoutCreateInfo plci{ VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO };
+        plci.setLayoutCount = 1; plci.pSetLayouts = &setLayout;
+        VK_CHECK(vkCreatePipelineLayout(v.device, &plci, nullptr, &layout));
+
+        VkPipelineShaderStageCreateInfo stages[2]{};
+        stages[0].sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO; stages[0].stage = VK_SHADER_STAGE_VERTEX_BIT;   stages[0].module = vmod; stages[0].pName = "main";
+        stages[1].sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO; stages[1].stage = VK_SHADER_STAGE_FRAGMENT_BIT; stages[1].module = fmod; stages[1].pName = "main";
+        VkVertexInputBindingDescription vib{ 0, 16, VK_VERTEX_INPUT_RATE_VERTEX };
+        VkVertexInputAttributeDescription via[2] = { { 0, 0, VK_FORMAT_R32G32_SFLOAT, 0 }, { 1, 0, VK_FORMAT_R32G32_SFLOAT, 8 } };
+        VkPipelineVertexInputStateCreateInfo vin{ VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO };
+        vin.vertexBindingDescriptionCount = 1; vin.pVertexBindingDescriptions = &vib;
+        vin.vertexAttributeDescriptionCount = 2; vin.pVertexAttributeDescriptions = via;
+        VkPipelineInputAssemblyStateCreateInfo ia{ VK_STRUCTURE_TYPE_PIPELINE_INPUT_ASSEMBLY_STATE_CREATE_INFO }; ia.topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;
+        VkViewport vp{ 0, 0, (float)W, (float)H, 0, 1 }; VkRect2D sc{ { 0, 0 }, { W, H } };
+        VkPipelineViewportStateCreateInfo vps{ VK_STRUCTURE_TYPE_PIPELINE_VIEWPORT_STATE_CREATE_INFO }; vps.viewportCount = 1; vps.pViewports = &vp; vps.scissorCount = 1; vps.pScissors = &sc;
+        VkPipelineRasterizationStateCreateInfo rs{ VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_STATE_CREATE_INFO }; rs.polygonMode = VK_POLYGON_MODE_FILL; rs.cullMode = VK_CULL_MODE_NONE; rs.frontFace = VK_FRONT_FACE_COUNTER_CLOCKWISE; rs.lineWidth = 1.0f;
+        VkPipelineMultisampleStateCreateInfo ms{ VK_STRUCTURE_TYPE_PIPELINE_MULTISAMPLE_STATE_CREATE_INFO }; ms.rasterizationSamples = VK_SAMPLE_COUNT_1_BIT;
+        VkPipelineColorBlendAttachmentState cba{}; cba.colorWriteMask = VK_COLOR_COMPONENT_R_BIT | VK_COLOR_COMPONENT_G_BIT | VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT;
+        VkPipelineColorBlendStateCreateInfo cb{ VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO }; cb.attachmentCount = 1; cb.pAttachments = &cba;
+        VkPipeline pipeline = VK_NULL_HANDLE;
+        VkGraphicsPipelineCreateInfo gpci{ VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO };
+        gpci.stageCount = 2; gpci.pStages = stages;
+        gpci.pVertexInputState = &vin; gpci.pInputAssemblyState = &ia; gpci.pViewportState = &vps;
+        gpci.pRasterizationState = &rs; gpci.pMultisampleState = &ms; gpci.pColorBlendState = &cb;
+        gpci.layout = layout; gpci.renderPass = renderPass; gpci.subpass = 0;
+        VK_CHECK(vkCreateGraphicsPipelines(v.device, VK_NULL_HANDLE, 1, &gpci, nullptr, &pipeline));
+
+        // Fullscreen quad (position.xy, texcoord.uv)
+        float quad[] = {
+            -1.f,  1.f, 0.f, 1.f,  -1.f, -1.f, 0.f, 0.f,   1.f, -1.f, 1.f, 0.f,
+            -1.f,  1.f, 0.f, 1.f,   1.f, -1.f, 1.f, 0.f,   1.f,  1.f, 1.f, 1.f,
+        };
+        VkBuffer vbuf; VkDeviceMemory vbufMem;
+        v.CreateBuffer(sizeof(quad), VK_BUFFER_USAGE_VERTEX_BUFFER_BIT, hostVis, vbuf, vbufMem);
+        vkMapMemory(v.device, vbufMem, 0, sizeof(quad), 0, &p); memcpy(p, quad, sizeof(quad)); vkUnmapMemory(v.device, vbufMem);
+
+        // Write the descriptor set
+        VkDescriptorBufferInfo bi[4] = {
+            { camBuf, 0, VK_WHOLE_SIZE }, { diskBuf, 0, VK_WHOLE_SIZE }, { objBuf, 0, VK_WHOLE_SIZE }, { simBuf, 0, VK_WHOLE_SIZE } };
+        VkDescriptorImageInfo ii{ sampler, cubeView, VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL };
+        VkWriteDescriptorSet writes[5]{};
+        for (int i = 0; i < 4; ++i) { writes[i].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET; writes[i].dstSet = set; writes[i].dstBinding = i; writes[i].descriptorCount = 1; writes[i].descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER; writes[i].pBufferInfo = &bi[i]; }
+        writes[4].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET; writes[4].dstSet = set; writes[4].dstBinding = 4; writes[4].descriptorCount = 1; writes[4].descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER; writes[4].pImageInfo = &ii;
+        vkUpdateDescriptorSets(v.device, 5, writes, 0, nullptr);
+
+        VkBuffer readback; VkDeviceMemory readbackMem;
+        v.CreateBuffer((VkDeviceSize)W * H * 4, VK_BUFFER_USAGE_TRANSFER_DST_BIT, hostVis, readback, readbackMem);
+
+        // Record + submit
+        VkCommandPool cpool = VK_NULL_HANDLE;
+        VkCommandPoolCreateInfo pci{ VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO }; pci.queueFamilyIndex = v.graphicsFamily;
+        VK_CHECK(vkCreateCommandPool(v.device, &pci, nullptr, &cpool));
+        VkCommandBuffer cmd = VK_NULL_HANDLE;
+        VkCommandBufferAllocateInfo cbai{ VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO }; cbai.commandPool = cpool; cbai.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY; cbai.commandBufferCount = 1;
+        VK_CHECK(vkAllocateCommandBuffers(v.device, &cbai, &cmd));
+        VkCommandBufferBeginInfo begin{ VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO }; begin.flags = VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT;
+        VK_CHECK(vkBeginCommandBuffer(cmd, &begin));
+
+        VkImageMemoryBarrier toDst{ VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER };
+        toDst.oldLayout = VK_IMAGE_LAYOUT_UNDEFINED; toDst.newLayout = VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL;
+        toDst.image = cube; toDst.subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 6 };
+        toDst.srcAccessMask = 0; toDst.dstAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT;
+        vkCmdPipelineBarrier(cmd, VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT, VK_PIPELINE_STAGE_TRANSFER_BIT, 0, 0, nullptr, 0, nullptr, 1, &toDst);
+        VkBufferImageCopy cubeCopy{}; cubeCopy.imageSubresource = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 0, 6 }; cubeCopy.imageExtent = { 1, 1, 1 };
+        vkCmdCopyBufferToImage(cmd, cubeStaging, cube, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, 1, &cubeCopy);
+        VkImageMemoryBarrier toRead = toDst;
+        toRead.oldLayout = VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL; toRead.newLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
+        toRead.srcAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT; toRead.dstAccessMask = VK_ACCESS_SHADER_READ_BIT;
+        vkCmdPipelineBarrier(cmd, VK_PIPELINE_STAGE_TRANSFER_BIT, VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT, 0, 0, nullptr, 0, nullptr, 1, &toRead);
+
+        VkClearValue clear{}; clear.color = { { 0, 0, 0, 1 } };
+        VkRenderPassBeginInfo rpbi{ VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO };
+        rpbi.renderPass = renderPass; rpbi.framebuffer = fb; rpbi.renderArea = { { 0, 0 }, { W, H } };
+        rpbi.clearValueCount = 1; rpbi.pClearValues = &clear;
+        vkCmdBeginRenderPass(cmd, &rpbi, VK_SUBPASS_CONTENTS_INLINE);
+        vkCmdBindPipeline(cmd, VK_PIPELINE_BIND_POINT_GRAPHICS, pipeline);
+        vkCmdBindDescriptorSets(cmd, VK_PIPELINE_BIND_POINT_GRAPHICS, layout, 0, 1, &set, 0, nullptr);
+        VkDeviceSize voff = 0; vkCmdBindVertexBuffers(cmd, 0, 1, &vbuf, &voff);
+        vkCmdDraw(cmd, 6, 1, 0, 0);
+        vkCmdEndRenderPass(cmd);
+        VkBufferImageCopy region{}; region.imageSubresource = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 0, 1 }; region.imageExtent = { W, H, 1 };
+        vkCmdCopyImageToBuffer(cmd, image, VK_IMAGE_LAYOUT_TRANSFER_SRC_OPTIMAL, readback, 1, &region);
+        VK_CHECK(vkEndCommandBuffer(cmd));
+
+        VkFence fence = VK_NULL_HANDLE; VkFenceCreateInfo fci{ VK_STRUCTURE_TYPE_FENCE_CREATE_INFO };
+        VK_CHECK(vkCreateFence(v.device, &fci, nullptr, &fence));
+        VkSubmitInfo submit{ VK_STRUCTURE_TYPE_SUBMIT_INFO }; submit.commandBufferCount = 1; submit.pCommandBuffers = &cmd;
+        VK_CHECK(vkQueueSubmit(v.graphicsQueue, 1, &submit, fence));
+        VK_CHECK(vkWaitForFences(v.device, 1, &fence, VK_TRUE, UINT64_MAX));
+
+        vkMapMemory(v.device, readbackMem, 0, (VkDeviceSize)W * H * 4, 0, &p);
+        stbi_write_png(pngPath, W, H, 4, p, W * 4);
+        vkUnmapMemory(v.device, readbackMem);
+        DONUT_INFO("Vulkan geodesic render written to {}", pngPath);
+
+        vkDestroyFence(v.device, fence, nullptr);
+        vkDestroyCommandPool(v.device, cpool, nullptr);
+        vkDestroyBuffer(v.device, readback, nullptr); vkFreeMemory(v.device, readbackMem, nullptr);
+        vkDestroyBuffer(v.device, vbuf, nullptr); vkFreeMemory(v.device, vbufMem, nullptr);
+        vkDestroyPipeline(v.device, pipeline, nullptr); vkDestroyPipelineLayout(v.device, layout, nullptr);
+        vkDestroyShaderModule(v.device, vmod, nullptr); vkDestroyShaderModule(v.device, fmod, nullptr);
+        vkDestroyDescriptorPool(v.device, pool, nullptr); vkDestroyDescriptorSetLayout(v.device, setLayout, nullptr);
+        vkDestroySampler(v.device, sampler, nullptr); vkDestroyImageView(v.device, cubeView, nullptr);
+        vkDestroyImage(v.device, cube, nullptr); vkFreeMemory(v.device, cubeMem, nullptr);
+        vkDestroyBuffer(v.device, cubeStaging, nullptr); vkFreeMemory(v.device, cubeStagingMem, nullptr);
+        vkDestroyBuffer(v.device, camBuf, nullptr); vkFreeMemory(v.device, camMem, nullptr);
+        vkDestroyBuffer(v.device, diskBuf, nullptr); vkFreeMemory(v.device, diskMem, nullptr);
+        vkDestroyBuffer(v.device, objBuf, nullptr); vkFreeMemory(v.device, objMem, nullptr);
+        vkDestroyBuffer(v.device, simBuf, nullptr); vkFreeMemory(v.device, simMem, nullptr);
+        vkDestroyFramebuffer(v.device, fb, nullptr); vkDestroyRenderPass(v.device, renderPass, nullptr);
+        vkDestroyImageView(v.device, view, nullptr); vkDestroyImage(v.device, image, nullptr); vkFreeMemory(v.device, imageMem, nullptr);
+        return true;
+    }
+
+    void VulkanContext::Shutdown()
+    {
+        Impl& v = *m_Impl;
+        if (v.device)   { vkDestroyDevice(v.device, nullptr);   v.device = VK_NULL_HANDLE; }
+        if (v.instance) { vkDestroyInstance(v.instance, nullptr); v.instance = VK_NULL_HANDLE; }
+    }
+
+    bool VulkanSelfTest()
+    {
+        VulkanContext ctx;
+        if (!ctx.Init())
+        {
+            DONUT_ERROR("Vulkan: initialization failed");
+            return false;
+        }
+        bool ok = ctx.SelfTestClear();
+        ok = ctx.SelfTestTriangle() && ok;
+        ctx.Shutdown();
+        return ok;
+    }
+}
diff --git a/src/Platform/Vulkan/VulkanContext.h b/src/Platform/Vulkan/VulkanContext.h
new file mode 100644
index 0000000..71bceda
--- /dev/null
+++ b/src/Platform/Vulkan/VulkanContext.h
@@ -0,0 +1,41 @@
+#pragma once
+
+// Pure-C++ interface to the Vulkan backend (no vulkan.h leaks into the rest of
+// the engine; the implementation lives in VulkanContext.cpp). On macOS Vulkan
+// runs through MoltenVK (Vulkan -> Metal).
+namespace Donut
+{
+    class VulkanContext
+    {
+    public:
+        VulkanContext();
+        ~VulkanContext();
+
+        // Creates the instance, picks a physical device, and creates the logical
+        // device + graphics queue. Returns false (and logs) on failure.
+        bool Init();
+        void Shutdown();
+
+        // Phase 1 verification: renders a known clear colour into an offscreen
+        // image and reads it back, confirming instance -> device -> render pass
+        // -> command buffer -> submit -> read-back all work end to end.
+        bool SelfTestClear();
+
+        // Phase 2/3 verification: builds a graphics pipeline from Slang-compiled
+        // SPIR-V and draws a full-screen gradient triangle into the offscreen
+        // image, confirming the SPIR-V -> pipeline -> draw path works.
+        bool SelfTestTriangle();
+
+        // B-3: renders the geodesic (black hole) fragment shader through Vulkan
+        // into an offscreen image and writes it to pngPath. Exercises UBOs,
+        // descriptor sets, a cubemap sampler and the geodesic pipeline.
+        bool RenderGeodesic(const char* pngPath);
+
+    private:
+        struct Impl;
+        Impl* m_Impl = nullptr;
+    };
+
+    // Convenience one-shot: Init() + SelfTestClear() + Shutdown(). Logs results.
+    bool VulkanSelfTest();
+}
diff --git a/src/Platform/Vulkan/VulkanRenderer.cpp b/src/Platform/Vulkan/VulkanRenderer.cpp
new file mode 100644
index 0000000..eb92695
--- /dev/null
+++ b/src/Platform/Vulkan/VulkanRenderer.cpp
@@ -0,0 +1,1235 @@
+#include "VulkanRenderer.h"
+#include "Core/Log.h"
+#include "Core/Camera.h"
+
+#define GLFW_INCLUDE_VULKAN
+#include <GLFW/glfw3.h>
+
+#include <imgui.h>
+#include <imgui_impl_glfw.h>
+#include <imgui_impl_vulkan.h>
+
+#include <glm/glm.hpp>
+#include <glm/gtc/matrix_transform.hpp>
+#include "stb_image.h"
+
+#include <vector>
+#include <algorithm>
+#include <cstring>
+#include <cstdlib>
+#include <fstream>
+
+namespace Donut
+{
+    #define VK_CHECK(expr)                                                     \
+        do {                                                                   \
+            VkResult _r = (expr);                                              \
+            if (_r != VK_SUCCESS) {                                            \
+                DONUT_ERROR("Vulkan: {} failed ({})", #expr, (int)_r);         \
+                return false;                                                  \
+            }                                                                  \
+        } while (0)
+
+    static constexpr int MAX_FRAMES_IN_FLIGHT = 2;
+
+    void VulkanPrepareGLFW()
+    {
+#ifdef __APPLE__
+        if (!getenv("VK_ICD_FILENAMES"))
+            setenv("VK_ICD_FILENAMES", "/opt/homebrew/etc/vulkan/icd.d/MoltenVK_icd.json", 0);
+        if (!getenv("VK_LAYER_PATH"))
+            setenv("VK_LAYER_PATH", "/opt/homebrew/share/vulkan/explicit_layer.d", 0);
+        if (!getenv("DYLD_LIBRARY_PATH"))
+            setenv("DYLD_LIBRARY_PATH", "/opt/homebrew/lib", 0);
+#endif
+        // GLFW dlopen's the Vulkan loader by bare name, which fails on
+        // macOS/Homebrew; hand it the loader entry point we already link against.
+        glfwInitVulkanLoader(vkGetInstanceProcAddr);
+    }
+
+    struct VulkanRenderer::Impl
+    {
+        GLFWwindow* window = nullptr;
+        int width = 0, height = 0;
+        bool framebufferResized = false;
+
+        VkInstance       instance = VK_NULL_HANDLE;
+        VkSurfaceKHR     surface  = VK_NULL_HANDLE;
+        VkPhysicalDevice physical = VK_NULL_HANDLE;
+        VkDevice         device   = VK_NULL_HANDLE;
+        uint32_t         graphicsFamily = 0, presentFamily = 0;
+        VkQueue          graphicsQueue = VK_NULL_HANDLE, presentQueue = VK_NULL_HANDLE;
+
+        VkSwapchainKHR   swapchain = VK_NULL_HANDLE;
+        VkFormat         swapchainFormat = VK_FORMAT_B8G8R8A8_UNORM;
+        VkExtent2D       swapchainExtent{};
+        std::vector<VkImage>       images;
+        std::vector<VkImageView>   imageViews;
+        VkRenderPass               renderPass = VK_NULL_HANDLE;
+        std::vector<VkFramebuffer> framebuffers;
+
+        VkCommandPool                commandPool = VK_NULL_HANDLE;
+        std::vector<VkCommandBuffer> commandBuffers;   // MAX_FRAMES_IN_FLIGHT
+
+        std::vector<VkSemaphore> imageAvailable;        // per frame in flight
+        std::vector<VkSemaphore> renderFinished;        // per swapchain image
+        std::vector<VkFence>     inFlight;              // per frame in flight
+        std::vector<VkFence>     imagesInFlight;        // per swapchain image
+        uint32_t currentFrame = 0;
+
+        VkDescriptorPool imguiPool = VK_NULL_HANDLE;
+        bool imguiInit = false;
+
+        VkPhysicalDeviceMemoryProperties memProps{};
+
+        // Geodesic scene, rendered every frame into a fixed low-resolution
+        // offscreen image (keeps each draw well under the Metal GPU watchdog),
+        // then upscaled onto the swapchain by the present pass below.
+        static constexpr uint32_t GEO_W = 480, GEO_H = 270;
+        VkImage       geoImage     = VK_NULL_HANDLE;
+        VkDeviceMemory geoImageMem = VK_NULL_HANDLE;
+        VkImageView   geoImageView = VK_NULL_HANDLE;
+        VkRenderPass  geoRenderPass = VK_NULL_HANDLE;
+        VkFramebuffer geoFramebuffer = VK_NULL_HANDLE;
+        VkBuffer camBuf = VK_NULL_HANDLE, diskBuf = VK_NULL_HANDLE, objBuf = VK_NULL_HANDLE, simBuf = VK_NULL_HANDLE;
+        VkDeviceMemory camMem = VK_NULL_HANDLE, diskMem = VK_NULL_HANDLE, objMem = VK_NULL_HANDLE, simMem = VK_NULL_HANDLE;
+        void* camMapped = nullptr;
+        void* simMapped = nullptr;
+        Camera camera{ 60.0f, (float)GEO_W / (float)GEO_H, 0.1f, 100.0f };
+        bool leftWasDown = false;
+        VkImage cubeImage = VK_NULL_HANDLE; VkDeviceMemory cubeMem = VK_NULL_HANDLE;
+        VkImageView cubeView = VK_NULL_HANDLE; VkSampler cubeSampler = VK_NULL_HANDLE;
+        VkDescriptorSetLayout geoSetLayout = VK_NULL_HANDLE;
+        VkDescriptorPool geoPool = VK_NULL_HANDLE;
+        VkDescriptorSet geoSet = VK_NULL_HANDLE;
+        VkPipelineLayout geoPipelineLayout = VK_NULL_HANDLE;
+        VkPipeline geoPipeline = VK_NULL_HANDLE;
+        VkBuffer quadVB = VK_NULL_HANDLE; VkDeviceMemory quadVBMem = VK_NULL_HANDLE;
+        double startTime = 0.0;
+        VkFence geoInUse = VK_NULL_HANDLE;  // previous frame's fence; guards the shared geodesic image
+
+        // Present pass: samples the geodesic image with a full-screen textured
+        // quad, drawn into the swapchain render pass just before the ImGui UI.
+        VkSampler presentSampler = VK_NULL_HANDLE;
+        VkDescriptorSetLayout presentSetLayout = VK_NULL_HANDLE;
+        VkDescriptorPool presentPool = VK_NULL_HANDLE;
+        VkDescriptorSet presentSet = VK_NULL_HANDLE;
+        VkPipelineLayout presentPipelineLayout = VK_NULL_HANDLE;
+        VkPipeline presentPipeline = VK_NULL_HANDLE;
+
+        uint32_t FindMemoryType(uint32_t typeFilter, VkMemoryPropertyFlags flags) const;
+        bool CreateBuffer(VkDeviceSize size, VkBufferUsageFlags usage, VkMemoryPropertyFlags props, VkBuffer& buf, VkDeviceMemory& mem) const;
+        static std::vector<uint32_t> LoadSpirv(const std::string& path);
+        bool CreateShaderModule(const std::string& path, VkShaderModule& out) const;
+
+        bool CreateInstance();
+        bool PickPhysicalAndDevice();
+        bool CreateSwapchain();
+        bool CreateImageViews();
+        bool CreateRenderPass();
+        bool CreateFramebuffers();
+        bool CreateCommandBuffers();
+        bool CreateSyncObjects();
+        bool CreateGeodesicResources();
+        bool CreateHDRICubemap(const char* path);
+        bool CreatePresentResources();
+        void ProcessInput();
+        void UpdateGeodesicUniforms();
+        void DestroyGeodesicResources();
+        bool RecreateSwapchain();
+        void CleanupSwapchain();
+        bool RecordCommandBuffer(VkCommandBuffer cmd, uint32_t imageIndex, const glm::vec4& clear, ImDrawData* drawData);
+    };
+
+    bool VulkanRenderer::Impl::CreateInstance()
+    {
+#ifdef __APPLE__
+        if (!getenv("VK_ICD_FILENAMES"))
+            setenv("VK_ICD_FILENAMES", "/opt/homebrew/etc/vulkan/icd.d/MoltenVK_icd.json", 0);
+        if (!getenv("VK_LAYER_PATH"))
+            setenv("VK_LAYER_PATH", "/opt/homebrew/share/vulkan/explicit_layer.d", 0);
+        // The Homebrew validation-layer manifest names the dylib without a path;
+        // let dlopen find it in the Homebrew lib dir.
+        if (!getenv("DYLD_LIBRARY_PATH"))
+            setenv("DYLD_LIBRARY_PATH", "/opt/homebrew/lib", 0);
+#endif
+        VkApplicationInfo app{ VK_STRUCTURE_TYPE_APPLICATION_INFO };
+        app.pApplicationName = "Donut";
+        app.apiVersion       = VK_API_VERSION_1_2;
+
+        uint32_t glfwExtCount = 0;
+        const char** glfwExts = glfwGetRequiredInstanceExtensions(&glfwExtCount);
+        if (!glfwExts) { DONUT_ERROR("Vulkan: GLFW reports no surface support"); return false; }
+        std::vector<const char*> exts;
+        for (uint32_t i = 0; i < glfwExtCount; ++i) exts.push_back(glfwExts[i]);
+        exts.push_back(VK_KHR_PORTABILITY_ENUMERATION_EXTENSION_NAME);
+        exts.push_back(VK_KHR_GET_PHYSICAL_DEVICE_PROPERTIES_2_EXTENSION_NAME);
+
+        std::vector<const char*> layers;
+        uint32_t layerCount = 0;
+        vkEnumerateInstanceLayerProperties(&layerCount, nullptr);
+        std::vector<VkLayerProperties> avail(layerCount);
+        vkEnumerateInstanceLayerProperties(&layerCount, avail.data());
+        for (const auto& l : avail)
+            if (std::strcmp(l.layerName, "VK_LAYER_KHRONOS_validation") == 0)
+                layers.push_back("VK_LAYER_KHRONOS_validation");
+
+        VkInstanceCreateInfo ici{ VK_STRUCTURE_TYPE_INSTANCE_CREATE_INFO };
+        ici.flags                   = VK_INSTANCE_CREATE_ENUMERATE_PORTABILITY_BIT_KHR;
+        ici.pApplicationInfo        = &app;
+        ici.enabledExtensionCount   = (uint32_t)exts.size();
+        ici.ppEnabledExtensionNames = exts.data();
+        ici.enabledLayerCount       = (uint32_t)layers.size();
+        ici.ppEnabledLayerNames     = layers.data();
+
+        VkResult r = vkCreateInstance(&ici, nullptr, &instance);
+        if (r != VK_SUCCESS && !layers.empty())
+        {
+            // The validation layer failed to load (its dylib isn't on the loader
+            // search path); it is optional, so retry without it.
+            DONUT_WARN("Vulkan: validation layer unavailable, continuing without it");
+            layers.clear();
+            ici.enabledLayerCount = 0;
+            ici.ppEnabledLayerNames = nullptr;
+            r = vkCreateInstance(&ici, nullptr, &instance);
+        }
+        if (r != VK_SUCCESS) { DONUT_ERROR("Vulkan: vkCreateInstance failed ({})", (int)r); return false; }
+
+        VK_CHECK(glfwCreateWindowSurface(instance, window, nullptr, &surface));
+        DONUT_INFO("Vulkan: instance + surface created (validation {})", layers.empty() ? "off" : "on");
+        return true;
+    }
+
+    bool VulkanRenderer::Impl::PickPhysicalAndDevice()
+    {
+        uint32_t count = 0;
+        vkEnumeratePhysicalDevices(instance, &count, nullptr);
+        if (count == 0) { DONUT_ERROR("Vulkan: no physical devices"); return false; }
+        std::vector<VkPhysicalDevice> devices(count);
+        vkEnumeratePhysicalDevices(instance, &count, devices.data());
+        physical = devices[0];
+
+        uint32_t qCount = 0;
+        vkGetPhysicalDeviceQueueFamilyProperties(physical, &qCount, nullptr);
+        std::vector<VkQueueFamilyProperties> qfams(qCount);
+        vkGetPhysicalDeviceQueueFamilyProperties(physical, &qCount, qfams.data());
+        bool foundG = false, foundP = false;
+        for (uint32_t i = 0; i < qCount; ++i)
+        {
+            if (!foundG && (qfams[i].queueFlags & VK_QUEUE_GRAPHICS_BIT)) { graphicsFamily = i; foundG = true; }
+            VkBool32 present = VK_FALSE;
+            vkGetPhysicalDeviceSurfaceSupportKHR(physical, i, surface, &present);
+            if (!foundP && present) { presentFamily = i; foundP = true; }
+        }
+        if (!foundG || !foundP) { DONUT_ERROR("Vulkan: no graphics/present queue"); return false; }
+
+        std::vector<const char*> devExts = { VK_KHR_SWAPCHAIN_EXTENSION_NAME };
+        uint32_t devExtCount = 0;
+        vkEnumerateDeviceExtensionProperties(physical, nullptr, &devExtCount, nullptr);
+        std::vector<VkExtensionProperties> devExtProps(devExtCount);
+        vkEnumerateDeviceExtensionProperties(physical, nullptr, &devExtCount, devExtProps.data());
+        for (const auto& e : devExtProps)
+            if (std::strcmp(e.extensionName, "VK_KHR_portability_subset") == 0)
+                devExts.push_back("VK_KHR_portability_subset");
+
+        float priority = 1.0f;
+        std::vector<VkDeviceQueueCreateInfo> qcis;
+        uint32_t families[2] = { graphicsFamily, presentFamily };
+        for (uint32_t i = 0; i < (graphicsFamily == presentFamily ? 1u : 2u); ++i)
+        {
+            VkDeviceQueueCreateInfo qci{ VK_STRUCTURE_TYPE_DEVICE_QUEUE_CREATE_INFO };
+            qci.queueFamilyIndex = families[i];
+            qci.queueCount = 1;
+            qci.pQueuePriorities = &priority;
+            qcis.push_back(qci);
+        }
+        VkDeviceCreateInfo dci{ VK_STRUCTURE_TYPE_DEVICE_CREATE_INFO };
+        dci.queueCreateInfoCount    = (uint32_t)qcis.size();
+        dci.pQueueCreateInfos       = qcis.data();
+        dci.enabledExtensionCount   = (uint32_t)devExts.size();
+        dci.ppEnabledExtensionNames = devExts.data();
+        VK_CHECK(vkCreateDevice(physical, &dci, nullptr, &device));
+        vkGetDeviceQueue(device, graphicsFamily, 0, &graphicsQueue);
+        vkGetDeviceQueue(device, presentFamily, 0, &presentQueue);
+
+        VkPhysicalDeviceProperties props{};
+        vkGetPhysicalDeviceProperties(physical, &props);
+        vkGetPhysicalDeviceMemoryProperties(physical, &memProps);
+        DONUT_INFO("Vulkan device: {}", props.deviceName);
+        return true;
+    }
+
+    bool VulkanRenderer::Impl::CreateSwapchain()
+    {
+        VkSurfaceCapabilitiesKHR caps{};
+        vkGetPhysicalDeviceSurfaceCapabilitiesKHR(physical, surface, &caps);
+
+        uint32_t fmtCount = 0;
+        vkGetPhysicalDeviceSurfaceFormatsKHR(physical, surface, &fmtCount, nullptr);
+        std::vector<VkSurfaceFormatKHR> formats(fmtCount);
+        vkGetPhysicalDeviceSurfaceFormatsKHR(physical, surface, &fmtCount, formats.data());
+        VkSurfaceFormatKHR chosen = formats[0];
+        for (const auto& f : formats)
+            if (f.format == VK_FORMAT_B8G8R8A8_UNORM && f.colorSpace == VK_COLOR_SPACE_SRGB_NONLINEAR_KHR)
+                chosen = f;
+        swapchainFormat = chosen.format;
+
+        if (caps.currentExtent.width != UINT32_MAX)
+            swapchainExtent = caps.currentExtent;
+        else
+        {
+            swapchainExtent.width  = std::clamp((uint32_t)width,  caps.minImageExtent.width,  caps.maxImageExtent.width);
+            swapchainExtent.height = std::clamp((uint32_t)height, caps.minImageExtent.height, caps.maxImageExtent.height);
+        }
+
+        uint32_t imageCount = caps.minImageCount + 1;
+        if (caps.maxImageCount > 0 && imageCount > caps.maxImageCount)
+            imageCount = caps.maxImageCount;
+
+        VkSwapchainCreateInfoKHR sci{ VK_STRUCTURE_TYPE_SWAPCHAIN_CREATE_INFO_KHR };
+        sci.surface          = surface;
+        sci.minImageCount    = imageCount;
+        sci.imageFormat      = chosen.format;
+        sci.imageColorSpace  = chosen.colorSpace;
+        sci.imageExtent      = swapchainExtent;
+        sci.imageArrayLayers = 1;
+        sci.imageUsage       = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT;
+        sci.preTransform     = caps.currentTransform;
+        sci.compositeAlpha   = VK_COMPOSITE_ALPHA_OPAQUE_BIT_KHR;
+        sci.presentMode      = VK_PRESENT_MODE_FIFO_KHR;   // always supported, vsync
+        sci.clipped          = VK_TRUE;
+
+        uint32_t famIdx[2] = { graphicsFamily, presentFamily };
+        if (graphicsFamily != presentFamily)
+        {
+            sci.imageSharingMode      = VK_SHARING_MODE_CONCURRENT;
+            sci.queueFamilyIndexCount = 2;
+            sci.pQueueFamilyIndices   = famIdx;
+        }
+        else
+            sci.imageSharingMode = VK_SHARING_MODE_EXCLUSIVE;
+
+        VK_CHECK(vkCreateSwapchainKHR(device, &sci, nullptr, &swapchain));
+        uint32_t n = 0;
+        vkGetSwapchainImagesKHR(device, swapchain, &n, nullptr);
+        images.resize(n);
+        vkGetSwapchainImagesKHR(device, swapchain, &n, images.data());
+        return true;
+    }
+
+    bool VulkanRenderer::Impl::CreateImageViews()
+    {
+        imageViews.resize(images.size());
+        for (size_t i = 0; i < images.size(); ++i)
+        {
+            VkImageViewCreateInfo vci{ VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO };
+            vci.image = images[i];
+            vci.viewType = VK_IMAGE_VIEW_TYPE_2D;
+            vci.format = swapchainFormat;
+            vci.subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1 };
+            VK_CHECK(vkCreateImageView(device, &vci, nullptr, &imageViews[i]));
+        }
+        return true;
+    }
+
+    bool VulkanRenderer::Impl::CreateRenderPass()
+    {
+        VkAttachmentDescription color{};
+        color.format = swapchainFormat;
+        color.samples = VK_SAMPLE_COUNT_1_BIT;
+        color.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR;
+        color.storeOp = VK_ATTACHMENT_STORE_OP_STORE;
+        color.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE;
+        color.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
+        color.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED;
+        color.finalLayout = VK_IMAGE_LAYOUT_PRESENT_SRC_KHR;
+
+        VkAttachmentReference ref{ 0, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL };
+        VkSubpassDescription subpass{};
+        subpass.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
+        subpass.colorAttachmentCount = 1;
+        subpass.pColorAttachments = &ref;
+
+        VkSubpassDependency dep{};
+        dep.srcSubpass = VK_SUBPASS_EXTERNAL;
+        dep.dstSubpass = 0;
+        dep.srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
+        dep.dstStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
+        dep.dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
+
+        VkRenderPassCreateInfo rpci{ VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO };
+        rpci.attachmentCount = 1; rpci.pAttachments = &color;
+        rpci.subpassCount = 1; rpci.pSubpasses = &subpass;
+        rpci.dependencyCount = 1; rpci.pDependencies = &dep;
+        VK_CHECK(vkCreateRenderPass(device, &rpci, nullptr, &renderPass));
+        return true;
+    }
+
+    bool VulkanRenderer::Impl::CreateFramebuffers()
+    {
+        framebuffers.resize(imageViews.size());
+        for (size_t i = 0; i < imageViews.size(); ++i)
+        {
+            VkFramebufferCreateInfo fbci{ VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO };
+            fbci.renderPass = renderPass;
+            fbci.attachmentCount = 1; fbci.pAttachments = &imageViews[i];
+            fbci.width = swapchainExtent.width; fbci.height = swapchainExtent.height; fbci.layers = 1;
+            VK_CHECK(vkCreateFramebuffer(device, &fbci, nullptr, &framebuffers[i]));
+        }
+        return true;
+    }
+
+    bool VulkanRenderer::Impl::CreateCommandBuffers()
+    {
+        VkCommandPoolCreateInfo pci{ VK_STRUCTURE_TYPE_COMMAND_POOL_CREATE_INFO };
+        pci.flags = VK_COMMAND_POOL_CREATE_RESET_COMMAND_BUFFER_BIT;
+        pci.queueFamilyIndex = graphicsFamily;
+        VK_CHECK(vkCreateCommandPool(device, &pci, nullptr, &commandPool));
+
+        commandBuffers.resize(MAX_FRAMES_IN_FLIGHT);
+        VkCommandBufferAllocateInfo cbai{ VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO };
+        cbai.commandPool = commandPool;
+        cbai.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY;
+        cbai.commandBufferCount = MAX_FRAMES_IN_FLIGHT;
+        VK_CHECK(vkAllocateCommandBuffers(device, &cbai, commandBuffers.data()));
+        return true;
+    }
+
+    bool VulkanRenderer::Impl::CreateSyncObjects()
+    {
+        imageAvailable.resize(MAX_FRAMES_IN_FLIGHT);
+        inFlight.resize(MAX_FRAMES_IN_FLIGHT);
+        renderFinished.resize(images.size());
+        imagesInFlight.assign(images.size(), VK_NULL_HANDLE);
+
+        VkSemaphoreCreateInfo sci{ VK_STRUCTURE_TYPE_SEMAPHORE_CREATE_INFO };
+        VkFenceCreateInfo fci{ VK_STRUCTURE_TYPE_FENCE_CREATE_INFO };
+        fci.flags = VK_FENCE_CREATE_SIGNALED_BIT;
+        for (int i = 0; i < MAX_FRAMES_IN_FLIGHT; ++i)
+        {
+            VK_CHECK(vkCreateSemaphore(device, &sci, nullptr, &imageAvailable[i]));
+            VK_CHECK(vkCreateFence(device, &fci, nullptr, &inFlight[i]));
+        }
+        for (size_t i = 0; i < images.size(); ++i)
+            VK_CHECK(vkCreateSemaphore(device, &sci, nullptr, &renderFinished[i]));
+        return true;
+    }
+
+    uint32_t VulkanRenderer::Impl::FindMemoryType(uint32_t typeFilter, VkMemoryPropertyFlags flags) const
+    {
+        for (uint32_t i = 0; i < memProps.memoryTypeCount; ++i)
+            if ((typeFilter & (1u << i)) && (memProps.memoryTypes[i].propertyFlags & flags) == flags)
+                return i;
+        return UINT32_MAX;
+    }
+
+    bool VulkanRenderer::Impl::CreateBuffer(VkDeviceSize size, VkBufferUsageFlags usage, VkMemoryPropertyFlags props,
+                                            VkBuffer& buf, VkDeviceMemory& mem) const
+    {
+        VkBufferCreateInfo bci{ VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO };
+        bci.size = size; bci.usage = usage; bci.sharingMode = VK_SHARING_MODE_EXCLUSIVE;
+        if (vkCreateBuffer(device, &bci, nullptr, &buf) != VK_SUCCESS) return false;
+        VkMemoryRequirements req{}; vkGetBufferMemoryRequirements(device, buf, &req);
+        VkMemoryAllocateInfo ai{ VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO };
+        ai.allocationSize = req.size;
+        ai.memoryTypeIndex = FindMemoryType(req.memoryTypeBits, props);
+        if (vkAllocateMemory(device, &ai, nullptr, &mem) != VK_SUCCESS) return false;
+        vkBindBufferMemory(device, buf, mem, 0);
+        return true;
+    }
+
+    std::vector<uint32_t> VulkanRenderer::Impl::LoadSpirv(const std::string& path)
+    {
+        std::ifstream file(path, std::ios::ate | std::ios::binary);
+        if (!file.is_open()) return {};
+        size_t size = (size_t)file.tellg();
+        std::vector<uint32_t> data(size / 4);
+        file.seekg(0);
+        file.read(reinterpret_cast<char*>(data.data()), size);
+        return data;
+    }
+
+    bool VulkanRenderer::Impl::CreateShaderModule(const std::string& path, VkShaderModule& out) const
+    {
+        auto spv = LoadSpirv(path);
+        if (spv.empty()) { DONUT_ERROR("Vulkan: failed to load SPIR-V {}", path); return false; }
+        VkShaderModuleCreateInfo ci{ VK_STRUCTURE_TYPE_SHADER_MODULE_CREATE_INFO };
+        ci.codeSize = spv.size() * 4; ci.pCode = spv.data();
+        return vkCreateShaderModule(device, &ci, nullptr, &out) == VK_SUCCESS;
+    }
+
+    bool VulkanRenderer::Impl::CreateGeodesicResources()
+    {
+        const VkFormat fmt = VK_FORMAT_R8G8B8A8_UNORM;
+        const VkMemoryPropertyFlags hostVis = VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT;
+        const float SagA_rs = 1.269e10f;
+
+        VkImageCreateInfo ici{ VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO };
+        ici.imageType = VK_IMAGE_TYPE_2D; ici.format = fmt; ici.extent = { GEO_W, GEO_H, 1 };
+        ici.mipLevels = 1; ici.arrayLayers = 1; ici.samples = VK_SAMPLE_COUNT_1_BIT;
+        ici.tiling = VK_IMAGE_TILING_OPTIMAL;
+        ici.usage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT | VK_IMAGE_USAGE_SAMPLED_BIT;
+        VK_CHECK(vkCreateImage(device, &ici, nullptr, &geoImage));
+        VkMemoryRequirements imReq{}; vkGetImageMemoryRequirements(device, geoImage, &imReq);
+        VkMemoryAllocateInfo imAlloc{ VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO };
+        imAlloc.allocationSize = imReq.size;
+        imAlloc.memoryTypeIndex = FindMemoryType(imReq.memoryTypeBits, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);
+        VK_CHECK(vkAllocateMemory(device, &imAlloc, nullptr, &geoImageMem));
+        VK_CHECK(vkBindImageMemory(device, geoImage, geoImageMem, 0));
+        VkImageViewCreateInfo vci{ VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO };
+        vci.image = geoImage; vci.viewType = VK_IMAGE_VIEW_TYPE_2D; vci.format = fmt;
+        vci.subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1 };
+        VK_CHECK(vkCreateImageView(device, &vci, nullptr, &geoImageView));
+
+        VkAttachmentDescription color{};
+        color.format = fmt; color.samples = VK_SAMPLE_COUNT_1_BIT;
+        color.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR; color.storeOp = VK_ATTACHMENT_STORE_OP_STORE;
+        color.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE; color.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
+        color.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED; color.finalLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
+        VkAttachmentReference ref{ 0, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL };
+        VkSubpassDescription subpass{}; subpass.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS;
+        subpass.colorAttachmentCount = 1; subpass.pColorAttachments = &ref;
+        VkSubpassDependency deps[2]{};
+        deps[0].srcSubpass = VK_SUBPASS_EXTERNAL; deps[0].dstSubpass = 0;
+        deps[0].srcStageMask = VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT; deps[0].srcAccessMask = VK_ACCESS_SHADER_READ_BIT;
+        deps[0].dstStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT; deps[0].dstAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
+        deps[1].srcSubpass = 0; deps[1].dstSubpass = VK_SUBPASS_EXTERNAL;
+        deps[1].srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT; deps[1].srcAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
+        deps[1].dstStageMask = VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT; deps[1].dstAccessMask = VK_ACCESS_SHADER_READ_BIT;
+        VkRenderPassCreateInfo rpci{ VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO };
+        rpci.attachmentCount = 1; rpci.pAttachments = &color;
+        rpci.subpassCount = 1; rpci.pSubpasses = &subpass;
+        rpci.dependencyCount = 2; rpci.pDependencies = deps;
+        VK_CHECK(vkCreateRenderPass(device, &rpci, nullptr, &geoRenderPass));
+        VkFramebufferCreateInfo fbci{ VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO };
+        fbci.renderPass = geoRenderPass; fbci.attachmentCount = 1; fbci.pAttachments = &geoImageView;
+        fbci.width = GEO_W; fbci.height = GEO_H; fbci.layers = 1;
+        VK_CHECK(vkCreateFramebuffer(device, &fbci, nullptr, &geoFramebuffer));
+
+        CreateBuffer(128, VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT, hostVis, camBuf, camMem);
+        CreateBuffer(32,  VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT, hostVis, diskBuf, diskMem);
+        CreateBuffer(800, VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT, hostVis, objBuf, objMem);
+        CreateBuffer(16,  VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT, hostVis, simBuf, simMem);
+
+        camera.SetCameraMode(CameraMode::Orbital);
+        camera.SetOrbitalTarget(glm::vec3(0.0f));
+        camera.SetOrbitalRadius(1e11);
+        camera.SetOrbitalLimits(4e10, 3e11);
+        camera.SetOrbitalSpeed(0.01f);
+        camera.SetZoomSpeed(1e10);
+        camera.SetAzimuth(0.0f);
+        camera.SetElevation(1.25f);
+
+        void* p = nullptr;
+        vkMapMemory(device, camMem, 0, 128, 0, &camMapped);  // camera UBO is refilled every frame
+
+        float diskData[8] = { SagA_rs * 2.2f, SagA_rs * 5.2f, 2.0f, SagA_rs * 0.1f, 0.1f, 0, 0, 0 };
+        vkMapMemory(device, diskMem, 0, 32, 0, &p); memcpy(p, diskData, sizeof(diskData)); vkUnmapMemory(device, diskMem);
+
+        std::vector<uint8_t> objData(800, 0);
+        int numObjects = 1; memcpy(objData.data(), &numObjects, 4);
+        float posRadius[4] = { 0, 0, 0, SagA_rs }; memcpy(objData.data() + 16, posRadius, 16);
+        float objColor[4] = { 0, 0, 0, 1 };        memcpy(objData.data() + 272, objColor, 16);
+        vkMapMemory(device, objMem, 0, 800, 0, &p); memcpy(p, objData.data(), 800); vkUnmapMemory(device, objMem);
+
+        vkMapMemory(device, simMem, 0, 16, 0, &simMapped);
+
+        if (!CreateHDRICubemap("Assets/HDRI/HDR_blue_nebulae-1.hdr")) return false;
+
+        VkDescriptorSetLayoutBinding binds[5]{};
+        for (int i = 0; i < 4; ++i) { binds[i].binding = i; binds[i].descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER; binds[i].descriptorCount = 1; binds[i].stageFlags = VK_SHADER_STAGE_FRAGMENT_BIT; }
+        binds[4].binding = 4; binds[4].descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER; binds[4].descriptorCount = 1; binds[4].stageFlags = VK_SHADER_STAGE_FRAGMENT_BIT;
+        VkDescriptorSetLayoutCreateInfo dslci{ VK_STRUCTURE_TYPE_DESCRIPTOR_SET_LAYOUT_CREATE_INFO };
+        dslci.bindingCount = 5; dslci.pBindings = binds;
+        VK_CHECK(vkCreateDescriptorSetLayout(device, &dslci, nullptr, &geoSetLayout));
+        VkDescriptorPoolSize psizes[2] = { { VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, 4 }, { VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, 1 } };
+        VkDescriptorPoolCreateInfo dpci{ VK_STRUCTURE_TYPE_DESCRIPTOR_POOL_CREATE_INFO };
+        dpci.maxSets = 1; dpci.poolSizeCount = 2; dpci.pPoolSizes = psizes;
+        VK_CHECK(vkCreateDescriptorPool(device, &dpci, nullptr, &geoPool));
+        VkDescriptorSetAllocateInfo dsai{ VK_STRUCTURE_TYPE_DESCRIPTOR_SET_ALLOCATE_INFO };
+        dsai.descriptorPool = geoPool; dsai.descriptorSetCount = 1; dsai.pSetLayouts = &geoSetLayout;
+        VK_CHECK(vkAllocateDescriptorSets(device, &dsai, &geoSet));
+        VkDescriptorBufferInfo bi[4] = { { camBuf, 0, VK_WHOLE_SIZE }, { diskBuf, 0, VK_WHOLE_SIZE }, { objBuf, 0, VK_WHOLE_SIZE }, { simBuf, 0, VK_WHOLE_SIZE } };
+        VkDescriptorImageInfo cubeInfo{ cubeSampler, cubeView, VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL };
+        VkWriteDescriptorSet writes[5]{};
+        for (int i = 0; i < 4; ++i) { writes[i].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET; writes[i].dstSet = geoSet; writes[i].dstBinding = i; writes[i].descriptorCount = 1; writes[i].descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER; writes[i].pBufferInfo = &bi[i]; }
+        writes[4].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET; writes[4].dstSet = geoSet; writes[4].dstBinding = 4; writes[4].descriptorCount = 1; writes[4].descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER; writes[4].pImageInfo = &cubeInfo;
+        vkUpdateDescriptorSets(device, 5, writes, 0, nullptr);
+
+        float quad[] = {
+            -1.f,  1.f, 0.f, 1.f,  -1.f, -1.f, 0.f, 0.f,   1.f, -1.f, 1.f, 0.f,
+            -1.f,  1.f, 0.f, 1.f,   1.f, -1.f, 1.f, 0.f,   1.f,  1.f, 1.f, 1.f,
+        };
+        CreateBuffer(sizeof(quad), VK_BUFFER_USAGE_VERTEX_BUFFER_BIT, hostVis, quadVB, quadVBMem);
+        vkMapMemory(device, quadVBMem, 0, sizeof(quad), 0, &p); memcpy(p, quad, sizeof(quad)); vkUnmapMemory(device, quadVBMem);
+
+        VkShaderModule vmod, fmod;
+        if (!CreateShaderModule("Assets/Shaders/generated/Geodesic.vertexMain.spv", vmod)) return false;
+        if (!CreateShaderModule("Assets/Shaders/generated/Geodesic.fragmentMain.spv", fmod)) return false;
+        VkPipelineLayoutCreateInfo plci{ VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO };
+        plci.setLayoutCount = 1; plci.pSetLayouts = &geoSetLayout;
+        VK_CHECK(vkCreatePipelineLayout(device, &plci, nullptr, &geoPipelineLayout));
+        VkPipelineShaderStageCreateInfo stages[2]{};
+        stages[0].sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO; stages[0].stage = VK_SHADER_STAGE_VERTEX_BIT;   stages[0].module = vmod; stages[0].pName = "main";
+        stages[1].sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO; stages[1].stage = VK_SHADER_STAGE_FRAGMENT_BIT; stages[1].module = fmod; stages[1].pName = "main";
+        VkVertexInputBindingDescription vib{ 0, 16, VK_VERTEX_INPUT_RATE_VERTEX };
+        VkVertexInputAttributeDescription via[2] = { { 0, 0, VK_FORMAT_R32G32_SFLOAT, 0 }, { 1, 0, VK_FORMAT_R32G32_SFLOAT, 8 } };
+        VkPipelineVertexInputStateCreateInfo vin{ VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO };
+        vin.vertexBindingDescriptionCount = 1; vin.pVertexBindingDescriptions = &vib;
+        vin.vertexAttributeDescriptionCount = 2; vin.pVertexAttributeDescriptions = via;
+        VkPipelineInputAssemblyStateCreateInfo ia{ VK_STRUCTURE_TYPE_PIPELINE_INPUT_ASSEMBLY_STATE_CREATE_INFO }; ia.topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;
+        VkViewport vp{ 0, 0, (float)GEO_W, (float)GEO_H, 0, 1 }; VkRect2D sc{ { 0, 0 }, { GEO_W, GEO_H } };
+        VkPipelineViewportStateCreateInfo vps{ VK_STRUCTURE_TYPE_PIPELINE_VIEWPORT_STATE_CREATE_INFO }; vps.viewportCount = 1; vps.pViewports = &vp; vps.scissorCount = 1; vps.pScissors = &sc;
+        VkPipelineRasterizationStateCreateInfo rs{ VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_STATE_CREATE_INFO }; rs.polygonMode = VK_POLYGON_MODE_FILL; rs.cullMode = VK_CULL_MODE_NONE; rs.frontFace = VK_FRONT_FACE_COUNTER_CLOCKWISE; rs.lineWidth = 1.0f;
+        VkPipelineMultisampleStateCreateInfo ms{ VK_STRUCTURE_TYPE_PIPELINE_MULTISAMPLE_STATE_CREATE_INFO }; ms.rasterizationSamples = VK_SAMPLE_COUNT_1_BIT;
+        VkPipelineColorBlendAttachmentState cba{}; cba.colorWriteMask = VK_COLOR_COMPONENT_R_BIT | VK_COLOR_COMPONENT_G_BIT | VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT;
+        VkPipelineColorBlendStateCreateInfo cb{ VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO }; cb.attachmentCount = 1; cb.pAttachments = &cba;
+        VkGraphicsPipelineCreateInfo gpci{ VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO };
+        gpci.stageCount = 2; gpci.pStages = stages;
+        gpci.pVertexInputState = &vin; gpci.pInputAssemblyState = &ia; gpci.pViewportState = &vps;
+        gpci.pRasterizationState = &rs; gpci.pMultisampleState = &ms; gpci.pColorBlendState = &cb;
+        gpci.layout = geoPipelineLayout; gpci.renderPass = geoRenderPass; gpci.subpass = 0;
+        VkResult pr = vkCreateGraphicsPipelines(device, VK_NULL_HANDLE, 1, &gpci, nullptr, &geoPipeline);
+        vkDestroyShaderModule(device, vmod, nullptr); vkDestroyShaderModule(device, fmod, nullptr);
+        if (pr != VK_SUCCESS) { DONUT_ERROR("Vulkan: geodesic pipeline creation failed ({})", (int)pr); return false; }
+
+        startTime = glfwGetTime();
+        UpdateGeodesicUniforms();
+        DONUT_INFO("Vulkan: geodesic resources ready ({}x{} offscreen)", (int)GEO_W, (int)GEO_H);
+        return true;
+    }
+
+    bool VulkanRenderer::Impl::CreateHDRICubemap(const char* path)
+    {
+        const VkMemoryPropertyFlags hostVis = VK_MEMORY_PROPERTY_HOST_VISIBLE_BIT | VK_MEMORY_PROPERTY_HOST_COHERENT_BIT;
+        const uint32_t FACE = 1024;
+        const VkFormat cubeFmt = VK_FORMAT_R16G16B16A16_SFLOAT;
+
+        VkImageCreateInfo cci{ VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO };
+        cci.flags = VK_IMAGE_CREATE_CUBE_COMPATIBLE_BIT;
+        cci.imageType = VK_IMAGE_TYPE_2D; cci.format = cubeFmt; cci.extent = { FACE, FACE, 1 };
+        cci.mipLevels = 1; cci.arrayLayers = 6; cci.samples = VK_SAMPLE_COUNT_1_BIT;
+        cci.tiling = VK_IMAGE_TILING_OPTIMAL;
+        cci.usage = VK_IMAGE_USAGE_COLOR_ATTACHMENT_BIT | VK_IMAGE_USAGE_SAMPLED_BIT | VK_IMAGE_USAGE_TRANSFER_DST_BIT;
+        VK_CHECK(vkCreateImage(device, &cci, nullptr, &cubeImage));
+        VkMemoryRequirements creq{}; vkGetImageMemoryRequirements(device, cubeImage, &creq);
+        VkMemoryAllocateInfo cai{ VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO };
+        cai.allocationSize = creq.size; cai.memoryTypeIndex = FindMemoryType(creq.memoryTypeBits, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);
+        VK_CHECK(vkAllocateMemory(device, &cai, nullptr, &cubeMem));
+        VK_CHECK(vkBindImageMemory(device, cubeImage, cubeMem, 0));
+        VkImageViewCreateInfo cvci{ VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO };
+        cvci.image = cubeImage; cvci.viewType = VK_IMAGE_VIEW_TYPE_CUBE; cvci.format = cubeFmt;
+        cvci.subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 6 };
+        VK_CHECK(vkCreateImageView(device, &cvci, nullptr, &cubeView));
+        VkSamplerCreateInfo csm{ VK_STRUCTURE_TYPE_SAMPLER_CREATE_INFO };
+        csm.magFilter = VK_FILTER_LINEAR; csm.minFilter = VK_FILTER_LINEAR;
+        csm.addressModeU = csm.addressModeV = csm.addressModeW = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE;
+        VK_CHECK(vkCreateSampler(device, &csm, nullptr, &cubeSampler));
+
+        int w = 0, h = 0, ch = 0;
+        float* pixels = stbi_loadf(path, &w, &h, &ch, 4);
+        if (!pixels)
+        {
+            DONUT_WARN("Vulkan: HDRI '{}' could not be loaded; using a dark background", path);
+            VkCommandBufferAllocateInfo cbai{ VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO };
+            cbai.commandPool = commandPool; cbai.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY; cbai.commandBufferCount = 1;
+            VkCommandBuffer cmd; VK_CHECK(vkAllocateCommandBuffers(device, &cbai, &cmd));
+            VkCommandBufferBeginInfo bi{ VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO }; bi.flags = VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT;
+            vkBeginCommandBuffer(cmd, &bi);
+            VkImageMemoryBarrier tb{ VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER };
+            tb.oldLayout = VK_IMAGE_LAYOUT_UNDEFINED; tb.newLayout = VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL;
+            tb.image = cubeImage; tb.subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 6 };
+            tb.srcAccessMask = 0; tb.dstAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT;
+            vkCmdPipelineBarrier(cmd, VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT, VK_PIPELINE_STAGE_TRANSFER_BIT, 0, 0, nullptr, 0, nullptr, 1, &tb);
+            VkClearColorValue dark{}; dark.float32[0] = 0.02f; dark.float32[1] = 0.02f; dark.float32[2] = 0.05f; dark.float32[3] = 1.0f;
+            VkImageSubresourceRange rng{ VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 6 };
+            vkCmdClearColorImage(cmd, cubeImage, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, &dark, 1, &rng);
+            VkImageMemoryBarrier rb = tb; rb.oldLayout = VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL; rb.newLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
+            rb.srcAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT; rb.dstAccessMask = VK_ACCESS_SHADER_READ_BIT;
+            vkCmdPipelineBarrier(cmd, VK_PIPELINE_STAGE_TRANSFER_BIT, VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT, 0, 0, nullptr, 0, nullptr, 1, &rb);
+            vkEndCommandBuffer(cmd);
+            VkSubmitInfo si{ VK_STRUCTURE_TYPE_SUBMIT_INFO }; si.commandBufferCount = 1; si.pCommandBuffers = &cmd;
+            vkQueueSubmit(graphicsQueue, 1, &si, VK_NULL_HANDLE); vkQueueWaitIdle(graphicsQueue);
+            vkFreeCommandBuffers(device, commandPool, 1, &cmd);
+            return true;
+        }
+
+        // Apple GPUs can't linearly filter RGBA32F, so store the equirect as
+        // RGBA16F (convert the loaded floats to half on the way into staging).
+        const VkFormat eqFmt = VK_FORMAT_R16G16B16A16_SFLOAT;
+        size_t texelCount = (size_t)w * h * 4;
+        VkDeviceSize eqSize = (VkDeviceSize)texelCount * sizeof(uint16_t);
+        VkBuffer eqStaging; VkDeviceMemory eqStagingMem;
+        if (!CreateBuffer(eqSize, VK_BUFFER_USAGE_TRANSFER_SRC_BIT, hostVis, eqStaging, eqStagingMem)) { stbi_image_free(pixels); return false; }
+        void* mp = nullptr; vkMapMemory(device, eqStagingMem, 0, eqSize, 0, &mp);
+        uint16_t* dst = (uint16_t*)mp;
+        for (size_t i = 0; i < texelCount; ++i) { __fp16 hf = (__fp16)pixels[i]; memcpy(&dst[i], &hf, sizeof(uint16_t)); }
+        vkUnmapMemory(device, eqStagingMem);
+        stbi_image_free(pixels);
+
+        VkImage eqImage; VkDeviceMemory eqMem;
+        VkImageCreateInfo eci{ VK_STRUCTURE_TYPE_IMAGE_CREATE_INFO };
+        eci.imageType = VK_IMAGE_TYPE_2D; eci.format = eqFmt; eci.extent = { (uint32_t)w, (uint32_t)h, 1 };
+        eci.mipLevels = 1; eci.arrayLayers = 1; eci.samples = VK_SAMPLE_COUNT_1_BIT;
+        eci.tiling = VK_IMAGE_TILING_OPTIMAL; eci.usage = VK_IMAGE_USAGE_TRANSFER_DST_BIT | VK_IMAGE_USAGE_SAMPLED_BIT;
+        VK_CHECK(vkCreateImage(device, &eci, nullptr, &eqImage));
+        VkMemoryRequirements ereq{}; vkGetImageMemoryRequirements(device, eqImage, &ereq);
+        VkMemoryAllocateInfo eai{ VK_STRUCTURE_TYPE_MEMORY_ALLOCATE_INFO };
+        eai.allocationSize = ereq.size; eai.memoryTypeIndex = FindMemoryType(ereq.memoryTypeBits, VK_MEMORY_PROPERTY_DEVICE_LOCAL_BIT);
+        VK_CHECK(vkAllocateMemory(device, &eai, nullptr, &eqMem));
+        VK_CHECK(vkBindImageMemory(device, eqImage, eqMem, 0));
+        VkImageView eqView;
+        VkImageViewCreateInfo evci{ VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO };
+        evci.image = eqImage; evci.viewType = VK_IMAGE_VIEW_TYPE_2D; evci.format = eqFmt;
+        evci.subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1 };
+        VK_CHECK(vkCreateImageView(device, &evci, nullptr, &eqView));
+        VkSampler eqSampler;
+        VkSamplerCreateInfo esm{ VK_STRUCTURE_TYPE_SAMPLER_CREATE_INFO };
+        esm.magFilter = VK_FILTER_LINEAR; esm.minFilter = VK_FILTER_LINEAR;
+        esm.addressModeU = VK_SAMPLER_ADDRESS_MODE_REPEAT;         // longitude wraps
+        esm.addressModeV = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE;  // latitude clamps
+        esm.addressModeW = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE;
+        VK_CHECK(vkCreateSampler(device, &esm, nullptr, &eqSampler));
+
+        VkImageView faceViews[6];
+        for (uint32_t i = 0; i < 6; ++i)
+        {
+            VkImageViewCreateInfo fvci{ VK_STRUCTURE_TYPE_IMAGE_VIEW_CREATE_INFO };
+            fvci.image = cubeImage; fvci.viewType = VK_IMAGE_VIEW_TYPE_2D; fvci.format = cubeFmt;
+            fvci.subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, i, 1 };
+            VK_CHECK(vkCreateImageView(device, &fvci, nullptr, &faceViews[i]));
+        }
+
+        VkAttachmentDescription color{};
+        color.format = cubeFmt; color.samples = VK_SAMPLE_COUNT_1_BIT;
+        color.loadOp = VK_ATTACHMENT_LOAD_OP_CLEAR; color.storeOp = VK_ATTACHMENT_STORE_OP_STORE;
+        color.stencilLoadOp = VK_ATTACHMENT_LOAD_OP_DONT_CARE; color.stencilStoreOp = VK_ATTACHMENT_STORE_OP_DONT_CARE;
+        color.initialLayout = VK_IMAGE_LAYOUT_UNDEFINED; color.finalLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
+        VkAttachmentReference ref{ 0, VK_IMAGE_LAYOUT_COLOR_ATTACHMENT_OPTIMAL };
+        VkSubpassDescription subpass{}; subpass.pipelineBindPoint = VK_PIPELINE_BIND_POINT_GRAPHICS; subpass.colorAttachmentCount = 1; subpass.pColorAttachments = &ref;
+        VkSubpassDependency dep{}; dep.srcSubpass = 0; dep.dstSubpass = VK_SUBPASS_EXTERNAL;
+        dep.srcStageMask = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT; dep.srcAccessMask = VK_ACCESS_COLOR_ATTACHMENT_WRITE_BIT;
+        dep.dstStageMask = VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT; dep.dstAccessMask = VK_ACCESS_SHADER_READ_BIT;
+        VkRenderPass rp;
+        VkRenderPassCreateInfo rpci{ VK_STRUCTURE_TYPE_RENDER_PASS_CREATE_INFO };
+        rpci.attachmentCount = 1; rpci.pAttachments = &color; rpci.subpassCount = 1; rpci.pSubpasses = &subpass; rpci.dependencyCount = 1; rpci.pDependencies = &dep;
+        VK_CHECK(vkCreateRenderPass(device, &rpci, nullptr, &rp));
+        VkFramebuffer faceFB[6];
+        for (uint32_t i = 0; i < 6; ++i)
+        {
+            VkFramebufferCreateInfo fbci{ VK_STRUCTURE_TYPE_FRAMEBUFFER_CREATE_INFO };
+            fbci.renderPass = rp; fbci.attachmentCount = 1; fbci.pAttachments = &faceViews[i]; fbci.width = FACE; fbci.height = FACE; fbci.layers = 1;
+            VK_CHECK(vkCreateFramebuffer(device, &fbci, nullptr, &faceFB[i]));
+        }
+
+        VkDescriptorSetLayoutBinding binds[2]{};
+        binds[0].binding = 0; binds[0].descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER; binds[0].descriptorCount = 1; binds[0].stageFlags = VK_SHADER_STAGE_VERTEX_BIT;
+        binds[1].binding = 1; binds[1].descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER; binds[1].descriptorCount = 1; binds[1].stageFlags = VK_SHADER_STAGE_FRAGMENT_BIT;
+        VkDescriptorSetLayout setLayout;
+        VkDescriptorSetLayoutCreateInfo dslci{ VK_STRUCTURE_TYPE_DESCRIPTOR_SET_LAYOUT_CREATE_INFO }; dslci.bindingCount = 2; dslci.pBindings = binds;
+        VK_CHECK(vkCreateDescriptorSetLayout(device, &dslci, nullptr, &setLayout));
+        VkDescriptorPoolSize psizes[2] = { { VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER, 6 }, { VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, 6 } };
+        VkDescriptorPool pool;
+        VkDescriptorPoolCreateInfo dpci{ VK_STRUCTURE_TYPE_DESCRIPTOR_POOL_CREATE_INFO }; dpci.maxSets = 6; dpci.poolSizeCount = 2; dpci.pPoolSizes = psizes;
+        VK_CHECK(vkCreateDescriptorPool(device, &dpci, nullptr, &pool));
+
+        VkShaderModule vmod, fmod;
+        if (!CreateShaderModule("Assets/Shaders/generated/EquirectToCubemap.vertexMain.spv", vmod)) return false;
+        if (!CreateShaderModule("Assets/Shaders/generated/EquirectToCubemap.fragmentMain.spv", fmod)) return false;
+        VkPipelineLayout playout;
+        VkPipelineLayoutCreateInfo plci{ VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO }; plci.setLayoutCount = 1; plci.pSetLayouts = &setLayout;
+        VK_CHECK(vkCreatePipelineLayout(device, &plci, nullptr, &playout));
+        VkPipelineShaderStageCreateInfo stages[2]{};
+        stages[0].sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO; stages[0].stage = VK_SHADER_STAGE_VERTEX_BIT;   stages[0].module = vmod; stages[0].pName = "main";
+        stages[1].sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO; stages[1].stage = VK_SHADER_STAGE_FRAGMENT_BIT; stages[1].module = fmod; stages[1].pName = "main";
+        VkVertexInputBindingDescription vib{ 0, 12, VK_VERTEX_INPUT_RATE_VERTEX };
+        VkVertexInputAttributeDescription via{ 0, 0, VK_FORMAT_R32G32B32_SFLOAT, 0 };
+        VkPipelineVertexInputStateCreateInfo vin{ VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO };
+        vin.vertexBindingDescriptionCount = 1; vin.pVertexBindingDescriptions = &vib; vin.vertexAttributeDescriptionCount = 1; vin.pVertexAttributeDescriptions = &via;
+        VkPipelineInputAssemblyStateCreateInfo ia{ VK_STRUCTURE_TYPE_PIPELINE_INPUT_ASSEMBLY_STATE_CREATE_INFO }; ia.topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;
+        VkViewport vp{ 0, 0, (float)FACE, (float)FACE, 0, 1 }; VkRect2D sc{ { 0, 0 }, { FACE, FACE } };
+        VkPipelineViewportStateCreateInfo vps{ VK_STRUCTURE_TYPE_PIPELINE_VIEWPORT_STATE_CREATE_INFO }; vps.viewportCount = 1; vps.pViewports = &vp; vps.scissorCount = 1; vps.pScissors = &sc;
+        VkPipelineRasterizationStateCreateInfo rs{ VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_STATE_CREATE_INFO }; rs.polygonMode = VK_POLYGON_MODE_FILL; rs.cullMode = VK_CULL_MODE_NONE; rs.frontFace = VK_FRONT_FACE_COUNTER_CLOCKWISE; rs.lineWidth = 1.0f;
+        VkPipelineMultisampleStateCreateInfo ms{ VK_STRUCTURE_TYPE_PIPELINE_MULTISAMPLE_STATE_CREATE_INFO }; ms.rasterizationSamples = VK_SAMPLE_COUNT_1_BIT;
+        VkPipelineColorBlendAttachmentState cba{}; cba.colorWriteMask = VK_COLOR_COMPONENT_R_BIT | VK_COLOR_COMPONENT_G_BIT | VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT;
+        VkPipelineColorBlendStateCreateInfo cb{ VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO }; cb.attachmentCount = 1; cb.pAttachments = &cba;
+        VkPipeline pipeline;
+        VkGraphicsPipelineCreateInfo gpci{ VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO };
+        gpci.stageCount = 2; gpci.pStages = stages; gpci.pVertexInputState = &vin; gpci.pInputAssemblyState = &ia; gpci.pViewportState = &vps;
+        gpci.pRasterizationState = &rs; gpci.pMultisampleState = &ms; gpci.pColorBlendState = &cb; gpci.layout = playout; gpci.renderPass = rp; gpci.subpass = 0;
+        VkResult pr = vkCreateGraphicsPipelines(device, VK_NULL_HANDLE, 1, &gpci, nullptr, &pipeline);
+        vkDestroyShaderModule(device, vmod, nullptr); vkDestroyShaderModule(device, fmod, nullptr);
+        if (pr != VK_SUCCESS) { DONUT_ERROR("Vulkan: equirect pipeline failed ({})", (int)pr); return false; }
+
+        float cubeVerts[] = {
+            -1,1,-1, -1,-1,-1, 1,-1,-1, 1,-1,-1, 1,1,-1, -1,1,-1,
+            -1,-1,1, -1,-1,-1, -1,1,-1, -1,1,-1, -1,1,1, -1,-1,1,
+             1,-1,-1, 1,-1,1, 1,1,1, 1,1,1, 1,1,-1, 1,-1,-1,
+            -1,-1,1, -1,1,1, 1,1,1, 1,1,1, 1,-1,1, -1,-1,1,
+            -1,1,-1, 1,1,-1, 1,1,1, 1,1,1, -1,1,1, -1,1,-1,
+            -1,-1,-1, -1,-1,1, 1,-1,-1, 1,-1,-1, -1,-1,1, 1,-1,1,
+        };
+        VkBuffer cubeVB; VkDeviceMemory cubeVBMem;
+        CreateBuffer(sizeof(cubeVerts), VK_BUFFER_USAGE_VERTEX_BUFFER_BIT, hostVis, cubeVB, cubeVBMem);
+        vkMapMemory(device, cubeVBMem, 0, sizeof(cubeVerts), 0, &mp); memcpy(mp, cubeVerts, sizeof(cubeVerts)); vkUnmapMemory(device, cubeVBMem);
+
+        glm::mat4 proj = glm::perspective(glm::radians(90.0f), 1.0f, 0.1f, 10.0f);
+        proj[1][1] *= -1.0f;  // Vulkan clip space is Y-down vs OpenGL
+        glm::mat4 views[6] = {
+            glm::lookAt(glm::vec3(0), glm::vec3( 1, 0, 0), glm::vec3(0, -1, 0)),
+            glm::lookAt(glm::vec3(0), glm::vec3(-1, 0, 0), glm::vec3(0, -1, 0)),
+            glm::lookAt(glm::vec3(0), glm::vec3( 0, 1, 0), glm::vec3(0, 0, 1)),
+            glm::lookAt(glm::vec3(0), glm::vec3( 0, -1, 0), glm::vec3(0, 0, -1)),
+            glm::lookAt(glm::vec3(0), glm::vec3( 0, 0, 1), glm::vec3(0, -1, 0)),
+            glm::lookAt(glm::vec3(0), glm::vec3( 0, 0, -1), glm::vec3(0, -1, 0)),
+        };
+        VkBuffer ubo[6]; VkDeviceMemory uboMem[6]; VkDescriptorSet sets[6];
+        for (uint32_t i = 0; i < 6; ++i)
+        {
+            CreateBuffer(128, VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT, hostVis, ubo[i], uboMem[i]);
+            glm::mat4 mats[2] = { glm::transpose(proj), glm::transpose(views[i]) };  // SPIR-V expects row-major
+            vkMapMemory(device, uboMem[i], 0, 128, 0, &mp); memcpy(mp, mats, 128); vkUnmapMemory(device, uboMem[i]);
+            VkDescriptorSetAllocateInfo dsai{ VK_STRUCTURE_TYPE_DESCRIPTOR_SET_ALLOCATE_INFO }; dsai.descriptorPool = pool; dsai.descriptorSetCount = 1; dsai.pSetLayouts = &setLayout;
+            VK_CHECK(vkAllocateDescriptorSets(device, &dsai, &sets[i]));
+            VkDescriptorBufferInfo bufInfo{ ubo[i], 0, VK_WHOLE_SIZE };
+            VkDescriptorImageInfo imgInfo{ eqSampler, eqView, VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL };
+            VkWriteDescriptorSet ws[2]{};
+            ws[0].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET; ws[0].dstSet = sets[i]; ws[0].dstBinding = 0; ws[0].descriptorCount = 1; ws[0].descriptorType = VK_DESCRIPTOR_TYPE_UNIFORM_BUFFER; ws[0].pBufferInfo = &bufInfo;
+            ws[1].sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET; ws[1].dstSet = sets[i]; ws[1].dstBinding = 1; ws[1].descriptorCount = 1; ws[1].descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER; ws[1].pImageInfo = &imgInfo;
+            vkUpdateDescriptorSets(device, 2, ws, 0, nullptr);
+        }
+
+        VkCommandBufferAllocateInfo cbai{ VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO };
+        cbai.commandPool = commandPool; cbai.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY; cbai.commandBufferCount = 1;
+        VkCommandBuffer cmd; VK_CHECK(vkAllocateCommandBuffers(device, &cbai, &cmd));
+        VkCommandBufferBeginInfo bi{ VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO }; bi.flags = VK_COMMAND_BUFFER_USAGE_ONE_TIME_SUBMIT_BIT;
+        VK_CHECK(vkBeginCommandBuffer(cmd, &bi));
+        VkImageMemoryBarrier toDst{ VK_STRUCTURE_TYPE_IMAGE_MEMORY_BARRIER };
+        toDst.oldLayout = VK_IMAGE_LAYOUT_UNDEFINED; toDst.newLayout = VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL;
+        toDst.image = eqImage; toDst.subresourceRange = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 1, 0, 1 };
+        toDst.srcAccessMask = 0; toDst.dstAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT;
+        vkCmdPipelineBarrier(cmd, VK_PIPELINE_STAGE_TOP_OF_PIPE_BIT, VK_PIPELINE_STAGE_TRANSFER_BIT, 0, 0, nullptr, 0, nullptr, 1, &toDst);
+        VkBufferImageCopy copy{}; copy.imageSubresource = { VK_IMAGE_ASPECT_COLOR_BIT, 0, 0, 1 }; copy.imageExtent = { (uint32_t)w, (uint32_t)h, 1 };
+        vkCmdCopyBufferToImage(cmd, eqStaging, eqImage, VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL, 1, &copy);
+        VkImageMemoryBarrier toRead = toDst; toRead.oldLayout = VK_IMAGE_LAYOUT_TRANSFER_DST_OPTIMAL; toRead.newLayout = VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL;
+        toRead.srcAccessMask = VK_ACCESS_TRANSFER_WRITE_BIT; toRead.dstAccessMask = VK_ACCESS_SHADER_READ_BIT;
+        vkCmdPipelineBarrier(cmd, VK_PIPELINE_STAGE_TRANSFER_BIT, VK_PIPELINE_STAGE_FRAGMENT_SHADER_BIT, 0, 0, nullptr, 0, nullptr, 1, &toRead);
+
+        VkClearValue clear{}; clear.color = { { 0, 0, 0, 1 } };
+        for (uint32_t i = 0; i < 6; ++i)
+        {
+            VkRenderPassBeginInfo rpbi{ VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO };
+            rpbi.renderPass = rp; rpbi.framebuffer = faceFB[i]; rpbi.renderArea = { { 0, 0 }, { FACE, FACE } }; rpbi.clearValueCount = 1; rpbi.pClearValues = &clear;
+            vkCmdBeginRenderPass(cmd, &rpbi, VK_SUBPASS_CONTENTS_INLINE);
+            vkCmdBindPipeline(cmd, VK_PIPELINE_BIND_POINT_GRAPHICS, pipeline);
+            vkCmdBindDescriptorSets(cmd, VK_PIPELINE_BIND_POINT_GRAPHICS, playout, 0, 1, &sets[i], 0, nullptr);
+            VkDeviceSize off = 0; vkCmdBindVertexBuffers(cmd, 0, 1, &cubeVB, &off);
+            vkCmdDraw(cmd, 36, 1, 0, 0);
+            vkCmdEndRenderPass(cmd);
+        }
+        VK_CHECK(vkEndCommandBuffer(cmd));
+        VkSubmitInfo si{ VK_STRUCTURE_TYPE_SUBMIT_INFO }; si.commandBufferCount = 1; si.pCommandBuffers = &cmd;
+        VK_CHECK(vkQueueSubmit(graphicsQueue, 1, &si, VK_NULL_HANDLE));
+        VK_CHECK(vkQueueWaitIdle(graphicsQueue));
+
+        vkFreeCommandBuffers(device, commandPool, 1, &cmd);
+        for (uint32_t i = 0; i < 6; ++i) { vkDestroyBuffer(device, ubo[i], nullptr); vkFreeMemory(device, uboMem[i], nullptr); vkDestroyFramebuffer(device, faceFB[i], nullptr); vkDestroyImageView(device, faceViews[i], nullptr); }
+        vkDestroyBuffer(device, cubeVB, nullptr); vkFreeMemory(device, cubeVBMem, nullptr);
+        vkDestroyPipeline(device, pipeline, nullptr); vkDestroyPipelineLayout(device, playout, nullptr);
+        vkDestroyDescriptorPool(device, pool, nullptr); vkDestroyDescriptorSetLayout(device, setLayout, nullptr);
+        vkDestroyRenderPass(device, rp, nullptr);
+        vkDestroySampler(device, eqSampler, nullptr); vkDestroyImageView(device, eqView, nullptr);
+        vkDestroyImage(device, eqImage, nullptr); vkFreeMemory(device, eqMem, nullptr);
+        vkDestroyBuffer(device, eqStaging, nullptr); vkFreeMemory(device, eqStagingMem, nullptr);
+        DONUT_INFO("Vulkan: HDRI cubemap built from {} ({}x{} equirect -> {}^2 cube)", path, w, h, (int)FACE);
+        return true;
+    }
+
+    bool VulkanRenderer::Impl::CreatePresentResources()
+    {
+        VkSamplerCreateInfo smci{ VK_STRUCTURE_TYPE_SAMPLER_CREATE_INFO };
+        smci.magFilter = VK_FILTER_LINEAR; smci.minFilter = VK_FILTER_LINEAR;
+        smci.addressModeU = smci.addressModeV = smci.addressModeW = VK_SAMPLER_ADDRESS_MODE_CLAMP_TO_EDGE;
+        VK_CHECK(vkCreateSampler(device, &smci, nullptr, &presentSampler));
+
+        VkDescriptorSetLayoutBinding bind{}; bind.binding = 0; bind.descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER; bind.descriptorCount = 1; bind.stageFlags = VK_SHADER_STAGE_FRAGMENT_BIT;
+        VkDescriptorSetLayoutCreateInfo dslci{ VK_STRUCTURE_TYPE_DESCRIPTOR_SET_LAYOUT_CREATE_INFO };
+        dslci.bindingCount = 1; dslci.pBindings = &bind;
+        VK_CHECK(vkCreateDescriptorSetLayout(device, &dslci, nullptr, &presentSetLayout));
+        VkDescriptorPoolSize psize{ VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, 1 };
+        VkDescriptorPoolCreateInfo dpci{ VK_STRUCTURE_TYPE_DESCRIPTOR_POOL_CREATE_INFO };
+        dpci.maxSets = 1; dpci.poolSizeCount = 1; dpci.pPoolSizes = &psize;
+        VK_CHECK(vkCreateDescriptorPool(device, &dpci, nullptr, &presentPool));
+        VkDescriptorSetAllocateInfo dsai{ VK_STRUCTURE_TYPE_DESCRIPTOR_SET_ALLOCATE_INFO };
+        dsai.descriptorPool = presentPool; dsai.descriptorSetCount = 1; dsai.pSetLayouts = &presentSetLayout;
+        VK_CHECK(vkAllocateDescriptorSets(device, &dsai, &presentSet));
+        VkDescriptorImageInfo ii{ presentSampler, geoImageView, VK_IMAGE_LAYOUT_SHADER_READ_ONLY_OPTIMAL };
+        VkWriteDescriptorSet write{ VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET };
+        write.dstSet = presentSet; write.dstBinding = 0; write.descriptorCount = 1; write.descriptorType = VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER; write.pImageInfo = &ii;
+        vkUpdateDescriptorSets(device, 1, &write, 0, nullptr);
+
+        VkShaderModule vmod, fmod;
+        if (!CreateShaderModule("Assets/Shaders/generated/TexturedQuad.vertexMain.spv", vmod)) return false;
+        if (!CreateShaderModule("Assets/Shaders/generated/TexturedQuad.fragmentMain.spv", fmod)) return false;
+        VkPipelineLayoutCreateInfo plci{ VK_STRUCTURE_TYPE_PIPELINE_LAYOUT_CREATE_INFO };
+        plci.setLayoutCount = 1; plci.pSetLayouts = &presentSetLayout;
+        VK_CHECK(vkCreatePipelineLayout(device, &plci, nullptr, &presentPipelineLayout));
+        VkPipelineShaderStageCreateInfo stages[2]{};
+        stages[0].sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO; stages[0].stage = VK_SHADER_STAGE_VERTEX_BIT;   stages[0].module = vmod; stages[0].pName = "main";
+        stages[1].sType = VK_STRUCTURE_TYPE_PIPELINE_SHADER_STAGE_CREATE_INFO; stages[1].stage = VK_SHADER_STAGE_FRAGMENT_BIT; stages[1].module = fmod; stages[1].pName = "main";
+        VkVertexInputBindingDescription vib{ 0, 16, VK_VERTEX_INPUT_RATE_VERTEX };
+        VkVertexInputAttributeDescription via[2] = { { 0, 0, VK_FORMAT_R32G32_SFLOAT, 0 }, { 1, 0, VK_FORMAT_R32G32_SFLOAT, 8 } };
+        VkPipelineVertexInputStateCreateInfo vin{ VK_STRUCTURE_TYPE_PIPELINE_VERTEX_INPUT_STATE_CREATE_INFO };
+        vin.vertexBindingDescriptionCount = 1; vin.pVertexBindingDescriptions = &vib;
+        vin.vertexAttributeDescriptionCount = 2; vin.pVertexAttributeDescriptions = via;
+        VkPipelineInputAssemblyStateCreateInfo ia{ VK_STRUCTURE_TYPE_PIPELINE_INPUT_ASSEMBLY_STATE_CREATE_INFO }; ia.topology = VK_PRIMITIVE_TOPOLOGY_TRIANGLE_LIST;
+        VkPipelineViewportStateCreateInfo vps{ VK_STRUCTURE_TYPE_PIPELINE_VIEWPORT_STATE_CREATE_INFO }; vps.viewportCount = 1; vps.scissorCount = 1;
+        VkDynamicState dyn[2] = { VK_DYNAMIC_STATE_VIEWPORT, VK_DYNAMIC_STATE_SCISSOR };
+        VkPipelineDynamicStateCreateInfo dsci{ VK_STRUCTURE_TYPE_PIPELINE_DYNAMIC_STATE_CREATE_INFO }; dsci.dynamicStateCount = 2; dsci.pDynamicStates = dyn;
+        VkPipelineRasterizationStateCreateInfo rs{ VK_STRUCTURE_TYPE_PIPELINE_RASTERIZATION_STATE_CREATE_INFO }; rs.polygonMode = VK_POLYGON_MODE_FILL; rs.cullMode = VK_CULL_MODE_NONE; rs.frontFace = VK_FRONT_FACE_COUNTER_CLOCKWISE; rs.lineWidth = 1.0f;
+        VkPipelineMultisampleStateCreateInfo ms{ VK_STRUCTURE_TYPE_PIPELINE_MULTISAMPLE_STATE_CREATE_INFO }; ms.rasterizationSamples = VK_SAMPLE_COUNT_1_BIT;
+        VkPipelineColorBlendAttachmentState cba{}; cba.colorWriteMask = VK_COLOR_COMPONENT_R_BIT | VK_COLOR_COMPONENT_G_BIT | VK_COLOR_COMPONENT_B_BIT | VK_COLOR_COMPONENT_A_BIT;
+        VkPipelineColorBlendStateCreateInfo cb{ VK_STRUCTURE_TYPE_PIPELINE_COLOR_BLEND_STATE_CREATE_INFO }; cb.attachmentCount = 1; cb.pAttachments = &cba;
+        VkGraphicsPipelineCreateInfo gpci{ VK_STRUCTURE_TYPE_GRAPHICS_PIPELINE_CREATE_INFO };
+        gpci.stageCount = 2; gpci.pStages = stages;
+        gpci.pVertexInputState = &vin; gpci.pInputAssemblyState = &ia; gpci.pViewportState = &vps;
+        gpci.pDynamicState = &dsci;
+        gpci.pRasterizationState = &rs; gpci.pMultisampleState = &ms; gpci.pColorBlendState = &cb;
+        gpci.layout = presentPipelineLayout; gpci.renderPass = renderPass; gpci.subpass = 0;
+        VkResult pr = vkCreateGraphicsPipelines(device, VK_NULL_HANDLE, 1, &gpci, nullptr, &presentPipeline);
+        vkDestroyShaderModule(device, vmod, nullptr); vkDestroyShaderModule(device, fmod, nullptr);
+        if (pr != VK_SUCCESS) { DONUT_ERROR("Vulkan: present pipeline creation failed ({})", (int)pr); return false; }
+        DONUT_INFO("Vulkan: present pipeline ready");
+        return true;
+    }
+
+    void VulkanRenderer::Impl::UpdateGeodesicUniforms()
+    {
+        struct CamUBO {
+            glm::vec3 pos; float p0; glm::vec3 right; float p1;
+            glm::vec3 up; float p2; glm::vec3 fwd; float p3;
+            float tanHalfFov; float aspect; uint32_t moving; int p4;
+        } camData{};
+        glm::vec3 pos   = camera.GetOrbitalPosition();
+        glm::vec3 fwd   = glm::normalize(camera.GetOrbitalTarget() - pos);
+        glm::vec3 right = glm::normalize(glm::cross(fwd, glm::vec3(0, 1, 0)));
+        camData.pos = pos; camData.right = right; camData.up = glm::cross(right, fwd); camData.fwd = fwd;
+        camData.tanHalfFov = (float)tan(glm::radians(60.0f * 0.5f));
+        camData.aspect = (float)GEO_W / (float)GEO_H;
+        camData.moving = camera.IsDragging() || camera.IsPanning() ? 1u : 0u;
+        if (camMapped) memcpy(camMapped, &camData, sizeof(camData));
+
+        // Fewer integration steps while the camera moves keeps dragging responsive;
+        // more steps once it settles renders the disk in full.
+        struct SimUBO { int stepsMoving; int stepsStatic; float earlyExit; float time; } sim;
+        sim.stepsMoving = 3500; sim.stepsStatic = 5000; sim.earlyExit = 5e12f;
+        sim.time = (float)(glfwGetTime() - startTime);
+        if (simMapped) memcpy(simMapped, &sim, sizeof(sim));
+    }
+
+    static double g_ScrollAccum = 0.0;
+    static GLFWscrollfun g_PrevScroll = nullptr;
+    static void DonutVkScrollCallback(GLFWwindow* w, double x, double y)
+    {
+        if (g_PrevScroll) g_PrevScroll(w, x, y);  // keep ImGui's scroll handling intact
+        g_ScrollAccum += y;
+    }
+
+    void VulkanRenderer::Impl::ProcessInput()
+    {
+        bool overUI = imguiInit && ImGui::GetIO().WantCaptureMouse;
+
+        bool leftDown = glfwGetMouseButton(window, GLFW_MOUSE_BUTTON_LEFT) == GLFW_PRESS;
+        if (leftDown && !leftWasDown && !overUI)
+            camera.ProcessOrbitalMouseButton(GLFW_MOUSE_BUTTON_LEFT, GLFW_PRESS, 0);
+        else if (!leftDown && leftWasDown)
+            camera.ProcessOrbitalMouseButton(GLFW_MOUSE_BUTTON_LEFT, GLFW_RELEASE, 0);
+        leftWasDown = leftDown;
+
+        double mx = 0, my = 0;
+        glfwGetCursorPos(window, &mx, &my);
+        camera.ProcessOrbitalMouseMove(mx, my);  // tracks last position internally; orbits only while dragging
+
+        double scroll = g_ScrollAccum; g_ScrollAccum = 0.0;
+        if (scroll != 0.0 && !overUI)
+            camera.ProcessOrbitalScroll(0.0, scroll);
+    }
+
+    void VulkanRenderer::Impl::DestroyGeodesicResources()
+    {
+        if (presentPipeline) vkDestroyPipeline(device, presentPipeline, nullptr);
+        if (presentPipelineLayout) vkDestroyPipelineLayout(device, presentPipelineLayout, nullptr);
+        if (presentPool) vkDestroyDescriptorPool(device, presentPool, nullptr);
+        if (presentSetLayout) vkDestroyDescriptorSetLayout(device, presentSetLayout, nullptr);
+        if (presentSampler) vkDestroySampler(device, presentSampler, nullptr);
+
+        if (geoPipeline) vkDestroyPipeline(device, geoPipeline, nullptr);
+        if (geoPipelineLayout) vkDestroyPipelineLayout(device, geoPipelineLayout, nullptr);
+        if (geoPool) vkDestroyDescriptorPool(device, geoPool, nullptr);
+        if (geoSetLayout) vkDestroyDescriptorSetLayout(device, geoSetLayout, nullptr);
+        if (quadVB) vkDestroyBuffer(device, quadVB, nullptr);
+        if (quadVBMem) vkFreeMemory(device, quadVBMem, nullptr);
+        if (cubeSampler) vkDestroySampler(device, cubeSampler, nullptr);
+        if (cubeView) vkDestroyImageView(device, cubeView, nullptr);
+        if (cubeImage) vkDestroyImage(device, cubeImage, nullptr);
+        if (cubeMem) vkFreeMemory(device, cubeMem, nullptr);
+        if (camMapped) { vkUnmapMemory(device, camMem); camMapped = nullptr; }
+        if (simMapped) { vkUnmapMemory(device, simMem); simMapped = nullptr; }
+        VkBuffer ubos[4] = { camBuf, diskBuf, objBuf, simBuf };
+        VkDeviceMemory umem[4] = { camMem, diskMem, objMem, simMem };
+        for (int i = 0; i < 4; ++i) { if (ubos[i]) vkDestroyBuffer(device, ubos[i], nullptr); if (umem[i]) vkFreeMemory(device, umem[i], nullptr); }
+        if (geoFramebuffer) vkDestroyFramebuffer(device, geoFramebuffer, nullptr);
+        if (geoRenderPass) vkDestroyRenderPass(device, geoRenderPass, nullptr);
+        if (geoImageView) vkDestroyImageView(device, geoImageView, nullptr);
+        if (geoImage) vkDestroyImage(device, geoImage, nullptr);
+        if (geoImageMem) vkFreeMemory(device, geoImageMem, nullptr);
+    }
+
+    bool VulkanRenderer::Impl::RecordCommandBuffer(VkCommandBuffer cmd, uint32_t imageIndex, const glm::vec4& clear, ImDrawData* drawData)
+    {
+        VkCommandBufferBeginInfo begin{ VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO };
+        VK_CHECK(vkBeginCommandBuffer(cmd, &begin));
+
+        // Geodesic offscreen pass
+        VkClearValue geoClear{}; geoClear.color = { { 0, 0, 0, 1 } };
+        VkRenderPassBeginInfo grp{ VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO };
+        grp.renderPass = geoRenderPass; grp.framebuffer = geoFramebuffer;
+        grp.renderArea = { { 0, 0 }, { GEO_W, GEO_H } };
+        grp.clearValueCount = 1; grp.pClearValues = &geoClear;
+        vkCmdBeginRenderPass(cmd, &grp, VK_SUBPASS_CONTENTS_INLINE);
+        vkCmdBindPipeline(cmd, VK_PIPELINE_BIND_POINT_GRAPHICS, geoPipeline);
+        vkCmdBindDescriptorSets(cmd, VK_PIPELINE_BIND_POINT_GRAPHICS, geoPipelineLayout, 0, 1, &geoSet, 0, nullptr);
+        VkDeviceSize off = 0; vkCmdBindVertexBuffers(cmd, 0, 1, &quadVB, &off);
+        vkCmdDraw(cmd, 6, 1, 0, 0);
+        vkCmdEndRenderPass(cmd);
+
+        // Swapchain pass: upscale the geodesic image, then the ImGui UI on top
+        VkClearValue cv{}; cv.color = { { clear.r, clear.g, clear.b, clear.a } };
+        VkRenderPassBeginInfo rpbi{ VK_STRUCTURE_TYPE_RENDER_PASS_BEGIN_INFO };
+        rpbi.renderPass = renderPass;
+        rpbi.framebuffer = framebuffers[imageIndex];
+        rpbi.renderArea = { { 0, 0 }, swapchainExtent };
+        rpbi.clearValueCount = 1; rpbi.pClearValues = &cv;
+        vkCmdBeginRenderPass(cmd, &rpbi, VK_SUBPASS_CONTENTS_INLINE);
+        vkCmdBindPipeline(cmd, VK_PIPELINE_BIND_POINT_GRAPHICS, presentPipeline);
+        // Negative-height viewport flips the geodesic image vertically so the scene
+        // reads the same as the OpenGL path (Vulkan's clip space is Y-down). Only
+        // this draw is affected; ImGui sets its own viewport.
+        VkViewport vp{ 0, (float)swapchainExtent.height, (float)swapchainExtent.width, -(float)swapchainExtent.height, 0, 1 };
+        VkRect2D scissor{ { 0, 0 }, swapchainExtent };
+        vkCmdSetViewport(cmd, 0, 1, &vp);
+        vkCmdSetScissor(cmd, 0, 1, &scissor);
+        vkCmdBindDescriptorSets(cmd, VK_PIPELINE_BIND_POINT_GRAPHICS, presentPipelineLayout, 0, 1, &presentSet, 0, nullptr);
+        vkCmdBindVertexBuffers(cmd, 0, 1, &quadVB, &off);
+        vkCmdDraw(cmd, 6, 1, 0, 0);
+        if (drawData)
+            ImGui_ImplVulkan_RenderDrawData(drawData, cmd);
+        vkCmdEndRenderPass(cmd);
+
+        VK_CHECK(vkEndCommandBuffer(cmd));
+        return true;
+    }
+
+    void VulkanRenderer::Impl::CleanupSwapchain()
+    {
+        for (auto fb : framebuffers) vkDestroyFramebuffer(device, fb, nullptr);
+        framebuffers.clear();
+        for (auto iv : imageViews) vkDestroyImageView(device, iv, nullptr);
+        imageViews.clear();
+        if (renderPass) { vkDestroyRenderPass(device, renderPass, nullptr); renderPass = VK_NULL_HANDLE; }
+        if (swapchain)  { vkDestroySwapchainKHR(device, swapchain, nullptr); swapchain = VK_NULL_HANDLE; }
+    }
+
+    bool VulkanRenderer::Impl::RecreateSwapchain()
+    {
+        // Wait until the window has a non-zero size (e.g. after un-minimizing).
+        int w = 0, h = 0;
+        glfwGetFramebufferSize(window, &w, &h);
+        while (w == 0 || h == 0)
+        {
+            glfwGetFramebufferSize(window, &w, &h);
+            glfwWaitEvents();
+        }
+        width = w; height = h;
+        vkDeviceWaitIdle(device);
+
+        CleanupSwapchain();
+        // renderFinished are tied to image count; recreate below via sync if it changed.
+        if (!CreateSwapchain())   return false;
+        if (!CreateImageViews())  return false;
+        if (!CreateRenderPass())  return false;
+        if (!CreateFramebuffers())return false;
+        imagesInFlight.assign(images.size(), VK_NULL_HANDLE);
+        return true;
+    }
+
+    VulkanRenderer::VulkanRenderer()  { m_Impl = new Impl(); }
+    VulkanRenderer::~VulkanRenderer() { Shutdown(); delete m_Impl; m_Impl = nullptr; }
+
+    bool VulkanRenderer::Init(void* glfwWindow, int width, int height)
+    {
+        Impl& v = *m_Impl;
+        v.window = (GLFWwindow*)glfwWindow;
+        v.width = width; v.height = height;
+
+        if (!v.CreateInstance())        return false;
+        if (!v.PickPhysicalAndDevice()) return false;
+        if (!v.CreateSwapchain())       return false;
+        if (!v.CreateImageViews())      return false;
+        if (!v.CreateRenderPass())      return false;
+        if (!v.CreateFramebuffers())    return false;
+        if (!v.CreateCommandBuffers())  return false;
+        if (!v.CreateSyncObjects())     return false;
+        if (!v.CreateGeodesicResources()) return false;
+        if (!v.CreatePresentResources())  return false;
+
+        DONUT_INFO("Vulkan renderer ready: {} swapchain images, {}x{}",
+                   (int)v.images.size(), v.swapchainExtent.width, v.swapchainExtent.height);
+        return true;
+    }
+
+    bool VulkanRenderer::InitImGui()
+    {
+        Impl& v = *m_Impl;
+        if (v.device == VK_NULL_HANDLE) return false;
+
+        VkDescriptorPoolSize poolSize{ VK_DESCRIPTOR_TYPE_COMBINED_IMAGE_SAMPLER, 1000 };
+        VkDescriptorPoolCreateInfo dpci{ VK_STRUCTURE_TYPE_DESCRIPTOR_POOL_CREATE_INFO };
+        dpci.flags = VK_DESCRIPTOR_POOL_CREATE_FREE_DESCRIPTOR_SET_BIT;
+        dpci.maxSets = 1000;
+        dpci.poolSizeCount = 1; dpci.pPoolSizes = &poolSize;
+        VK_CHECK(vkCreateDescriptorPool(v.device, &dpci, nullptr, &v.imguiPool));
+
+        IMGUI_CHECKVERSION();
+        ImGui::CreateContext();
+        ImGuiIO& io = ImGui::GetIO();
+        io.ConfigFlags |= ImGuiConfigFlags_NavEnableKeyboard;
+        io.ConfigFlags |= ImGuiConfigFlags_DockingEnable;
+        ImGui::StyleColorsDark();
+
+        ImGui_ImplGlfw_InitForVulkan(v.window, true);
+        g_PrevScroll = glfwSetScrollCallback(v.window, DonutVkScrollCallback);  // chain ImGui + camera zoom
+        ImGui_ImplVulkan_InitInfo info{};
+        info.ApiVersion     = VK_API_VERSION_1_2;
+        info.Instance       = v.instance;
+        info.PhysicalDevice = v.physical;
+        info.Device         = v.device;
+        info.QueueFamily    = v.graphicsFamily;
+        info.Queue          = v.graphicsQueue;
+        info.DescriptorPool = v.imguiPool;
+        info.RenderPass     = v.renderPass;
+        info.MinImageCount  = 2;
+        info.ImageCount     = (uint32_t)v.images.size();
+        info.MSAASamples    = VK_SAMPLE_COUNT_1_BIT;
+        if (!ImGui_ImplVulkan_Init(&info))
+        {
+            DONUT_ERROR("Vulkan: ImGui_ImplVulkan_Init failed");
+            return false;
+        }
+
+        v.imguiInit = true;
+        DONUT_INFO("Vulkan: ImGui backend initialized");
+        return true;
+    }
+
+    void VulkanRenderer::OnResize(int width, int height)
+    {
+        m_Impl->framebufferResized = true;
+        m_Impl->width = width; m_Impl->height = height;
+    }
+
+    void VulkanRenderer::DrawFrame(const glm::vec4& clearColor, const std::function<void()>& buildUI)
+    {
+        Impl& v = *m_Impl;
+        if (v.device == VK_NULL_HANDLE) return;
+
+        ImDrawData* drawData = nullptr;
+        if (v.imguiInit)
+        {
+            ImGui_ImplVulkan_NewFrame();
+            ImGui_ImplGlfw_NewFrame();
+            ImGui::NewFrame();
+            if (buildUI) buildUI();
+            ImGui::Render();
+            drawData = ImGui::GetDrawData();
+        }
+
+        vkWaitForFences(v.device, 1, &v.inFlight[v.currentFrame], VK_TRUE, UINT64_MAX);
+
+        uint32_t imageIndex = 0;
+        VkResult r = vkAcquireNextImageKHR(v.device, v.swapchain, UINT64_MAX,
+                                           v.imageAvailable[v.currentFrame], VK_NULL_HANDLE, &imageIndex);
+        if (r == VK_ERROR_OUT_OF_DATE_KHR) { v.RecreateSwapchain(); return; }
+        if (r != VK_SUCCESS && r != VK_SUBOPTIMAL_KHR) { DONUT_ERROR("Vulkan: acquire failed ({})", (int)r); return; }
+
+        if (v.imagesInFlight[imageIndex] != VK_NULL_HANDLE)
+            vkWaitForFences(v.device, 1, &v.imagesInFlight[imageIndex], VK_TRUE, UINT64_MAX);
+        v.imagesInFlight[imageIndex] = v.inFlight[v.currentFrame];
+
+        // The geodesic offscreen image is shared across frames in flight; wait for
+        // the previous frame to finish reading it before overwriting it this frame.
+        if (v.geoInUse != VK_NULL_HANDLE)
+            vkWaitForFences(v.device, 1, &v.geoInUse, VK_TRUE, UINT64_MAX);
+        v.ProcessInput();
+        v.UpdateGeodesicUniforms();
+
+        vkResetCommandBuffer(v.commandBuffers[v.currentFrame], 0);
+        if (!v.RecordCommandBuffer(v.commandBuffers[v.currentFrame], imageIndex, clearColor, drawData)) return;
+
+        VkPipelineStageFlags waitStage = VK_PIPELINE_STAGE_COLOR_ATTACHMENT_OUTPUT_BIT;
+        VkSubmitInfo submit{ VK_STRUCTURE_TYPE_SUBMIT_INFO };
+        submit.waitSemaphoreCount   = 1;
+        submit.pWaitSemaphores      = &v.imageAvailable[v.currentFrame];
+        submit.pWaitDstStageMask    = &waitStage;
+        submit.commandBufferCount   = 1;
+        submit.pCommandBuffers      = &v.commandBuffers[v.currentFrame];
+        submit.signalSemaphoreCount = 1;
+        submit.pSignalSemaphores    = &v.renderFinished[imageIndex];
+
+        vkResetFences(v.device, 1, &v.inFlight[v.currentFrame]);
+        if (vkQueueSubmit(v.graphicsQueue, 1, &submit, v.inFlight[v.currentFrame]) != VK_SUCCESS)
+        { DONUT_ERROR("Vulkan: queue submit failed"); return; }
+        v.geoInUse = v.inFlight[v.currentFrame];
+
+        VkPresentInfoKHR present{ VK_STRUCTURE_TYPE_PRESENT_INFO_KHR };
+        present.waitSemaphoreCount = 1;
+        present.pWaitSemaphores    = &v.renderFinished[imageIndex];
+        present.swapchainCount     = 1;
+        present.pSwapchains        = &v.swapchain;
+        present.pImageIndices      = &imageIndex;
+        r = vkQueuePresentKHR(v.presentQueue, &present);
+        if (r == VK_ERROR_OUT_OF_DATE_KHR || r == VK_SUBOPTIMAL_KHR || v.framebufferResized)
+        {
+            v.framebufferResized = false;
+            v.RecreateSwapchain();
+        }
+
+        v.currentFrame = (v.currentFrame + 1) % MAX_FRAMES_IN_FLIGHT;
+    }
+
+    void VulkanRenderer::Shutdown()
+    {
+        Impl& v = *m_Impl;
+        if (v.device == VK_NULL_HANDLE) { if (v.instance && v.surface) { vkDestroySurfaceKHR(v.instance, v.surface, nullptr); v.surface = VK_NULL_HANDLE; } if (v.instance) { vkDestroyInstance(v.instance, nullptr); v.instance = VK_NULL_HANDLE; } return; }
+
+        vkDeviceWaitIdle(v.device);
+        v.DestroyGeodesicResources();
+        if (v.imguiInit)
+        {
+            ImGui_ImplVulkan_Shutdown();
+            ImGui_ImplGlfw_Shutdown();
+            ImGui::DestroyContext();
+            v.imguiInit = false;
+        }
+        if (v.imguiPool) { vkDestroyDescriptorPool(v.device, v.imguiPool, nullptr); v.imguiPool = VK_NULL_HANDLE; }
+        for (auto s : v.renderFinished) vkDestroySemaphore(v.device, s, nullptr);
+        for (auto s : v.imageAvailable) vkDestroySemaphore(v.device, s, nullptr);
+        for (auto f : v.inFlight)       vkDestroyFence(v.device, f, nullptr);
+        v.renderFinished.clear(); v.imageAvailable.clear(); v.inFlight.clear();
+        if (v.commandPool) { vkDestroyCommandPool(v.device, v.commandPool, nullptr); v.commandPool = VK_NULL_HANDLE; }
+        v.CleanupSwapchain();
+        vkDestroyDevice(v.device, nullptr); v.device = VK_NULL_HANDLE;
+        if (v.surface)  { vkDestroySurfaceKHR(v.instance, v.surface, nullptr); v.surface = VK_NULL_HANDLE; }
+        if (v.instance) { vkDestroyInstance(v.instance, nullptr); v.instance = VK_NULL_HANDLE; }
+    }
+}
diff --git a/src/Platform/Vulkan/VulkanRenderer.h b/src/Platform/Vulkan/VulkanRenderer.h
new file mode 100644
index 0000000..9b5a23f
--- /dev/null
+++ b/src/Platform/Vulkan/VulkanRenderer.h
@@ -0,0 +1,40 @@
+#pragma once
+
+#include <glm/glm.hpp>
+#include <functional>
+
+// Live-window Vulkan backend: owns the instance, surface, device, swapchain,
+// render pass, framebuffers and per-frame synchronization, and drives the
+// acquire -> record -> submit -> present loop. Pure-C++ header (no vulkan.h /
+// glfw leak); the GLFW window is passed as an opaque handle.
+namespace Donut
+{
+    // Must be called BEFORE glfwInit() when the Vulkan API is selected: points
+    // GLFW at the loader the app links against (GLFW's own dlopen fails on
+    // macOS/Homebrew) and configures the MoltenVK ICD / layer paths.
+    void VulkanPrepareGLFW();
+
+    class VulkanRenderer
+    {
+    public:
+        VulkanRenderer();
+        ~VulkanRenderer();
+
+        // glfwWindow must be a GLFW window created with GLFW_NO_API.
+        bool Init(void* glfwWindow, int width, int height);
+        void Shutdown();
+
+        // Creates the ImGui context + Vulkan/GLFW backends. Call after Init().
+        bool InitImGui();
+
+        // Renders + presents one frame: clears to clearColor, then (if InitImGui
+        // ran) opens an ImGui frame, invokes buildUI to populate it, and draws it.
+        void DrawFrame(const glm::vec4& clearColor, const std::function<void()>& buildUI = {});
+
+        void OnResize(int width, int height);
+
+    private:
+        struct Impl;
+        Impl* m_Impl = nullptr;
+    };
+}