3 files changed, 16 insertions, 1 deletions

diff --git a/src/platform/opengl/opengl_device.cpp b/src/platform/opengl/opengl_device.cpp
index 8516a3c..82fdae1 100644
--- a/src/platform/opengl/opengl_device.cpp
+++ b/src/platform/opengl/opengl_device.cpp
@@ -230,6 +230,7 @@ namespace Donut::RHI
             }
             auto resize(int w, int h) -> void override { m_width = w; m_height = h; }
             auto wait_idle() -> void override { glFinish(); }
+            auto set_vsync(bool enabled) -> void override { glfwSwapInterval(enabled ? 1 : 0); }
 
             auto create_buffer(BufferType t, size_t size, const void* data) -> Ref<Buffer> override
             { return create_ref<GLBuffer>(t, size, data); }
diff --git a/src/platform/vulkan/vulkan_common.h b/src/platform/vulkan/vulkan_common.h
index 0faa107..5ae257e 100644
--- a/src/platform/vulkan/vulkan_common.h
+++ b/src/platform/vulkan/vulkan_common.h
@@ -267,6 +267,7 @@ namespace Donut::RHI
         auto shutdown() -> void override;
         auto resize(int width, int height) -> void override { m_framebuffer_resized = true; m_width = width; m_height = height; }
         auto wait_idle() -> void override { if (m_device) vkDeviceWaitIdle(m_device); }
+        auto set_vsync(bool enabled) -> void override { m_vsync = enabled; m_framebuffer_resized = true; }
 
         auto create_buffer(BufferType type, size_t size, const void* data) -> Ref<Buffer> override;
         auto create_texture(int w, int h, Format format, Filter filter, const void* data) -> Ref<Texture> override;
@@ -305,6 +306,7 @@ namespace Donut::RHI
         GLFWwindow* m_window = nullptr;
         int m_width = 0, m_height = 0;
         bool m_framebuffer_resized = false;
+        bool m_vsync = true;
         std::string m_gpu_name;
 
         VkInstance       m_instance = VK_NULL_HANDLE;
diff --git a/src/platform/vulkan/vulkan_swapchain.cpp b/src/platform/vulkan/vulkan_swapchain.cpp
index fe5bd38..5bf2f60 100644
--- a/src/platform/vulkan/vulkan_swapchain.cpp
+++ b/src/platform/vulkan/vulkan_swapchain.cpp
@@ -117,7 +117,19 @@ namespace Donut::RHI
         sci.imageExtent = m_extent; 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; sci.clipped = VK_TRUE;
+        // FIFO is always available (vsync). With vsync off, prefer IMMEDIATE
+        // (uncapped, may tear) then MAILBOX, if the surface supports them.
+        VkPresentModeKHR present_mode = VK_PRESENT_MODE_FIFO_KHR;
+        if (!m_vsync)
+        {
+            uint32_t pmc = 0; vkGetPhysicalDeviceSurfacePresentModesKHR(m_physical, m_surface, &pmc, nullptr);
+            std::vector<VkPresentModeKHR> modes(pmc);
+            vkGetPhysicalDeviceSurfacePresentModesKHR(m_physical, m_surface, &pmc, modes.data());
+            auto has = [&](VkPresentModeKHR m){ return std::find(modes.begin(), modes.end(), m) != modes.end(); };
+            if (has(VK_PRESENT_MODE_IMMEDIATE_KHR))    present_mode = VK_PRESENT_MODE_IMMEDIATE_KHR;
+            else if (has(VK_PRESENT_MODE_MAILBOX_KHR)) present_mode = VK_PRESENT_MODE_MAILBOX_KHR;
+        }
+        sci.presentMode = present_mode; sci.clipped = VK_TRUE;
         uint32_t fam[2] = { m_graphics_family, m_present_family };
         if (m_graphics_family != m_present_family)
         { sci.imageSharingMode = VK_SHARING_MODE_CONCURRENT; sci.queueFamilyIndexCount = 2; sci.pQueueFamilyIndices = fam; }