[feat]: implement ui layer arch

5 files changed, 822 insertions, 2 deletions

diff --git a/src/platform/opengl/opengl_device.cpp b/src/platform/opengl/opengl_device.cpp
index c4332fa..8516a3c 100644
--- a/src/platform/opengl/opengl_device.cpp
+++ b/src/platform/opengl/opengl_device.cpp
@@ -2,8 +2,8 @@
 
 #include "core/log.h"
 #include "core/hdri_manager.h"
-#include "rendering/shader.h"
-#include "rendering/texture.h"
+#include "shader.h"
+#include "texture.h"
 
 #include <glad/glad.h>
 #include <GLFW/glfw3.h>
@@ -220,6 +220,11 @@ namespace Donut::RHI
             }
             auto shutdown() -> void override
             {
+                // Free the HDRIManager's cached GL cubemaps while our context is
+                // still current (they are static-singleton-owned; letting them
+                // destruct at program exit would glDeleteTextures after the context
+                // is gone and crash on close).
+                HDRIManager::get().clear_cache();
                 if (m_imgui) { ImGui_ImplOpenGL3_Shutdown(); ImGui_ImplGlfw_Shutdown(); ImGui::DestroyContext(); m_imgui = false; }
                 if (m_vao) { glDeleteVertexArrays(1, &m_vao); m_vao = 0; }
             }
diff --git a/src/platform/opengl/shader.cpp b/src/platform/opengl/shader.cpp
new file mode 100644
index 0000000..80015e6
--- /dev/null
+++ b/src/platform/opengl/shader.cpp
@@ -0,0 +1,354 @@
+#include "shader.h"
+
+#include <glad/glad.h>
+#include <glm/gtc/type_ptr.hpp>
+
+#include <fstream>
+#include <iostream>
+
+namespace Donut
+{
+    static uint32_t ShaderTypeFromString(const std::string& type)
+    {
+        if (type == "vertex")
+            return GL_VERTEX_SHADER;
+        if (type == "fragment" || type == "pixel")
+            return GL_FRAGMENT_SHADER;
+        if (type == "compute")
+            return GL_COMPUTE_SHADER;
+        return 0;
+    }
+
+    // Shaders are authored in Slang and compiled to assets/shaders/generated/
+    // <name>.glsl by tools/compile-shaders.sh. Given a legacy ".../<name>.glsl"
+    // path, prefer that generated file when present; otherwise fall back to the
+    // hand-written GLSL (e.g. shaders not yet ported to Slang).
+    static std::string ResolveShaderPath(const std::string& filepath)
+    {
+        size_t slash = filepath.find_last_of("/\\");
+        std::string dir  = (slash == std::string::npos) ? std::string() : filepath.substr(0, slash + 1);
+        std::string file = (slash == std::string::npos) ? filepath : filepath.substr(slash + 1);
+        size_t dot = file.rfind('.');
+        std::string base = (dot == std::string::npos) ? file : file.substr(0, dot);
+
+        std::string generated = dir + "generated/" + base + ".glsl";
+        std::ifstream test(generated);
+        if (test.good())
+            return generated;
+        return filepath;
+    }
+
+    Shader::Shader(const std::string& filepath)
+    {
+        std::string resolved = ResolveShaderPath(filepath);
+        m_is_slang = (resolved != filepath);
+        std::string source = read_file(resolved);
+        auto shader_sources = pre_process(source);
+        compile(shader_sources);
+
+        auto last_slash = filepath.find_last_of("/\\");
+        last_slash = last_slash == std::string::npos ? 0 : last_slash + 1;
+        auto last_dot = filepath.rfind('.');
+        auto count = last_dot == std::string::npos ? filepath.size() - last_slash : last_dot - last_slash;
+        m_name = filepath.substr(last_slash, count);
+    }
+
+    Shader::Shader(const std::string& name, const std::string& vertex_src, const std::string& fragment_src)
+        : m_name(name)
+    {
+        std::unordered_map<uint32_t, std::string> sources;
+        sources[GL_VERTEX_SHADER] = vertex_src;
+        sources[GL_FRAGMENT_SHADER] = fragment_src;
+        compile(sources);
+    }
+
+    Shader::Shader(const std::string& name, const std::string& compute_src)
+        : m_name(name)
+    {
+        std::unordered_map<uint32_t, std::string> sources;
+        sources[GL_COMPUTE_SHADER] = compute_src;
+        compile(sources);
+    }
+
+    Shader::~Shader()
+    {
+        glDeleteProgram(m_renderer_id);
+    }
+
+    auto Shader::read_file(const std::string& filepath) -> std::string
+    {
+        std::string result;
+        std::ifstream in(filepath, std::ios::in |
+                                   std::ios::binary);
+
+        if (in)
+        {
+            in.seekg(0, std::ios::end);
+            size_t size = in.tellg();
+            if (size != -1)
+            {
+                result.resize(size);
+                in.seekg(0, std::ios::beg);
+                in.read(&result[0], size);
+            }
+        }
+        return result;
+    }
+
+    auto Shader::pre_process(const std::string& source) -> std::unordered_map<uint32_t, std::string>
+    {
+        std::unordered_map<uint32_t, std::string> shader_sources;
+
+        const char* type_token = "#type";
+        size_t type_token_length = strlen(type_token);
+        size_t pos = source.find(type_token, 0);
+
+        while (pos != std::string::npos)
+        {
+            size_t eol = source.find_first_of("\r\n", pos);
+            size_t begin = pos + type_token_length + 1;
+            std::string type = source.substr(begin, eol - begin);
+
+            size_t next_line_pos = source.find_first_not_of("\r\n", eol);
+            pos = source.find(type_token, next_line_pos);
+            shader_sources[ShaderTypeFromString(type)] = (pos == std::string::npos) ? source.substr(next_line_pos) :
+            source.substr(next_line_pos, pos - next_line_pos);
+        }
+
+        return shader_sources;
+    }
+
+    auto Shader::compile(const std::unordered_map<uint32_t, std::string>& shader_sources) -> void
+    {
+        uint32_t program = glCreateProgram();
+        std::vector<uint32_t> glShaderIDs(shader_sources.size());
+        for (auto& kv : shader_sources)
+        {
+            uint32_t type = kv.first;
+            const std::string& source = kv.second;
+
+            uint32_t shader = glCreateShader(type);
+            const char* source_c_str = source.c_str();
+            glShaderSource(shader, 1, &source_c_str, 0);
+            glCompileShader(shader);
+
+            int is_compiled = 0;
+            glGetShaderiv(shader, GL_COMPILE_STATUS, &is_compiled);
+            if (is_compiled == GL_FALSE)
+            {
+                int max_length = 0;
+                glGetShaderiv(shader, GL_INFO_LOG_LENGTH, &max_length);
+                std::vector<char> info_log(max_length);
+                glGetShaderInfoLog(shader, max_length, &max_length, &info_log[0]);
+                glDeleteShader(shader);
+                for (auto id : glShaderIDs)
+                    glDeleteShader(id);
+                glDeleteProgram(program);
+                m_renderer_id = 0;
+                // info_log.data() is null when the driver returns an empty log
+                // (e.g. macOS rejecting a compute shader); streaming a null
+                // char* into std::cout calls strlen(NULL) and crashes.
+                const char* log = info_log.empty() ? "" : info_log.data();
+                std::cout << "Shader compilation failure!" << std::endl << log << std::endl;
+                return;
+            }
+            glAttachShader(program, shader);
+            glShaderIDs.push_back(shader);
+        }
+
+        m_renderer_id = program;
+        glLinkProgram(m_renderer_id);
+
+        int is_linked = 0;
+        glGetProgramiv(m_renderer_id, GL_LINK_STATUS, (int*)&is_linked);
+        if (is_linked == GL_FALSE)
+        {
+            int max_length = 0;
+            glGetProgramiv(m_renderer_id, GL_INFO_LOG_LENGTH, &max_length);
+            std::vector<char> info_log(max_length);
+            glGetProgramInfoLog(m_renderer_id, max_length, &max_length, &info_log[0]);
+            glDeleteProgram(m_renderer_id);
+            for (auto id : glShaderIDs)
+                glDeleteShader(id);
+            m_renderer_id = 0;
+            const char* log = info_log.empty() ? "" : info_log.data();
+            std::cout << "Shader link failure!" << std::endl << log << std::endl;
+            return;
+        }
+
+        for (auto id : glShaderIDs)
+        {
+            glDetachShader(m_renderer_id, id);
+            glDeleteShader(id);
+        }
+    }
+
+    auto Shader::bind() const -> void
+    {
+        glUseProgram(m_renderer_id);
+    }
+
+    auto Shader::unbind() const -> void
+    {
+        glUseProgram(0);
+    }
+
+    auto Shader::set_int(const std::string& name, int value) -> void
+    {
+        upload_uniform_int(name, value);
+    }
+
+    auto Shader::set_int_array(const std::string& name, int* values, uint32_t count) -> void
+    {
+        upload_uniform_int_array(name, values, count);
+    }
+
+    auto Shader::set_float(const std::string& name, float value) -> void
+    {
+        upload_uniform_float(name, value);
+    }
+
+    auto Shader::set_float2(const std::string& name, const glm::vec2& value) -> void
+    {
+        upload_uniform_float2(name, value);
+    }
+
+    auto Shader::set_float3(const std::string& name, const glm::vec3& value) -> void
+    {
+        upload_uniform_float3(name, value);
+    }
+
+    auto Shader::set_float4(const std::string& name, const glm::vec4& value) -> void
+    {
+        upload_uniform_float4(name, value);
+    }
+
+    auto Shader::set_mat4(const std::string& name, const glm::mat4& value) -> void
+    {
+        upload_uniform_mat4(name, value);
+    }
+
+    auto Shader::upload_uniform_int(const std::string& name, int value) -> void
+    {
+        int location = glGetUniformLocation(m_renderer_id, name.c_str());
+        glUniform1i(location, value);
+    }
+
+    auto Shader::upload_uniform_int_array(const std::string& name, int* values, uint32_t count) -> void
+    {
+        int location = glGetUniformLocation(m_renderer_id, name.c_str());
+        glUniform1iv(location, count, values);
+    }
+
+    auto Shader::upload_uniform_float(const std::string& name, float value) -> void
+    {
+        int location = glGetUniformLocation(m_renderer_id, name.c_str());
+        glUniform1f(location, value);
+    }
+
+    auto Shader::upload_uniform_float2(const std::string& name, const glm::vec2& value) -> void
+    {
+        int location = glGetUniformLocation(m_renderer_id, name.c_str());
+        glUniform2f(location, value.x, value.y);
+    }
+
+    auto Shader::upload_uniform_float3(const std::string& name, const glm::vec3& value) -> void
+    {
+        int location = glGetUniformLocation(m_renderer_id, name.c_str());
+        glUniform3f(location, value.x, value.y, value.z);
+    }
+
+    auto Shader::upload_uniform_float4(const std::string& name, const glm::vec4& value) -> void
+    {
+        int location = glGetUniformLocation(m_renderer_id, name.c_str());
+        glUniform4f(location, value.x, value.y, value.z, value.w);
+    }
+
+    auto Shader::upload_uniform_mat3(const std::string& name, const glm::mat3& matrix) -> void
+    {
+        int location = glGetUniformLocation(m_renderer_id, name.c_str());
+        glUniformMatrix3fv(location, 1, m_is_slang ? GL_TRUE : GL_FALSE, glm::value_ptr(matrix));
+    }
+
+    auto Shader::upload_uniform_mat4(const std::string& name, const glm::mat4& matrix) -> void
+    {
+        int location = glGetUniformLocation(m_renderer_id, name.c_str());
+        glUniformMatrix4fv(location, 1, m_is_slang ? GL_TRUE : GL_FALSE, glm::value_ptr(matrix));
+    }
+
+    auto Shader::dispatch(uint32_t x, uint32_t y, uint32_t z) -> void
+    {
+        // Compute shaders require OpenGL 4.3+. On drivers that cap out earlier
+        // (e.g. macOS, which is frozen at 4.1) glDispatchCompute is never
+        // loaded and the pointer is null. Guard so we no-op instead of crash.
+        if (m_renderer_id == 0 || glDispatchCompute == nullptr)
+            return;
+        glDispatchCompute(x, y, z);
+    }
+
+    auto Shader::dispatch_indirect(uint32_t offset) -> void
+    {
+        if (m_renderer_id == 0 || glDispatchComputeIndirect == nullptr)
+            return;
+        glDispatchComputeIndirect(offset);
+    }
+
+    auto Shader::memory_barrier(uint32_t barriers) -> void
+    {
+        if (glMemoryBarrier == nullptr)
+            return;
+        glMemoryBarrier(barriers);
+    }
+
+    auto Shader::create(const std::string& filepath) -> Shader*
+    {
+        return new Shader(filepath);
+    }
+
+    auto Shader::create(const std::string& name, const std::string& vertex_src, const std::string& fragment_src) -> Shader*
+    {
+        return new Shader(name, vertex_src, fragment_src);
+    }
+
+    auto Shader::create_compute(const std::string& name, const std::string& compute_src) -> Shader*
+    {
+        return new Shader(name, compute_src);
+    }
+
+    auto ShaderLibrary::add(const Ref<Shader>& shader) -> void
+    {
+        auto& name = shader->get_name();
+        add(name, shader);
+    }
+
+    auto ShaderLibrary::add(const std::string& name, const Ref<Shader>& shader) -> void
+    {
+        m_shaders[name] = shader;
+    }
+
+    auto ShaderLibrary::load(const std::string& filepath) -> Ref<Shader>
+    {
+        auto shader = Ref<Shader>(Shader::create(filepath));
+        add(shader);
+        return shader;
+    }
+
+    auto ShaderLibrary::load(const std::string& name, const std::string& filepath) -> Ref<Shader>
+    {
+        auto shader = Ref<Shader>(Shader::create(filepath));
+        add(name, shader);
+        return shader;
+    }
+
+    auto ShaderLibrary::Get(const std::string& name) -> Ref<Shader>
+    {
+        if (exists(name))
+            return m_shaders[name];
+        return nullptr;
+    }
+
+    auto ShaderLibrary::exists(const std::string& name) const -> bool
+    {
+        return m_shaders.find(name) != m_shaders.end();
+    }
+};
diff --git a/src/platform/opengl/shader.h b/src/platform/opengl/shader.h
new file mode 100644
index 0000000..409aca3
--- /dev/null
+++ b/src/platform/opengl/shader.h
@@ -0,0 +1,82 @@
+#pragma once
+
+#include "core/memory.h"
+
+#include <string>
+#include <unordered_map>
+#include <glm/glm.hpp>
+
+#define SHADER_STORAGE_BARRIER_BIT    0x00002000
+#define UNIFORM_BARRIER_BIT           0x00000004
+#define TEXTURE_FETCH_BARRIER_BIT     0x00000008
+#define IMAGE_ACCESS_BARRIER_BIT      0x00000020
+
+namespace Donut
+{
+    class Shader
+    {
+    public:
+        Shader(const std::string& filepath);
+        Shader(const std::string& name, const std::string& vertex_src, const std::string& fragment_src);
+        Shader(const std::string& name, const std::string& compute_src);
+        ~Shader();
+
+        auto bind() const -> void;
+        auto unbind() const -> void;
+
+        auto set_int(     const std::string& name, int value) -> void;
+        auto set_int_array(const std::string& name, int* values, uint32_t count) -> void;
+        auto set_float(   const std::string& name, float value) -> void;
+        auto set_float2(  const std::string& name, const glm::vec2& value) -> void;
+        auto set_float3(  const std::string& name, const glm::vec3& value) -> void;
+        auto set_float4(  const std::string& name, const glm::vec4& value) -> void;
+        auto set_mat4(    const std::string& name, const glm::mat4& value) -> void;
+
+        auto dispatch(uint32_t x, uint32_t y = 1, uint32_t z = 1) -> void;
+        auto dispatch_indirect(uint32_t offset = 0) -> void;
+        auto memory_barrier(uint32_t barriers) -> void;
+
+        auto get_name() const -> const std::string& { return m_name; }
+        auto get_renderer_id() const -> uint32_t { return m_renderer_id; }
+
+        auto upload_uniform_int(     const std::string& name, int value) -> void;
+        auto upload_uniform_int_array(const std::string& name, int* values, uint32_t count) -> void;
+        auto upload_uniform_float(   const std::string& name, float value) -> void;
+        auto upload_uniform_float2(  const std::string& name, const glm::vec2& value) -> void;
+        auto upload_uniform_float3(  const std::string& name, const glm::vec3& value) -> void;
+        auto upload_uniform_float4(  const std::string& name, const glm::vec4& value) -> void;
+        auto upload_uniform_mat3(    const std::string& name, const glm::mat3& matrix) -> void;
+        auto upload_uniform_mat4(    const std::string& name, const glm::mat4& matrix) -> void;
+
+        static auto create(const std::string& filepath) -> Shader*;
+        static auto create(const std::string& name, const std::string& vertex_src, const std::string& fragment_src) -> Shader*;
+        static auto create_compute(const std::string& name, const std::string& compute_src) -> Shader*;
+
+    private:
+        auto read_file(const std::string& filepath) -> std::string;
+        auto pre_process(const std::string& source) -> std::unordered_map<uint32_t, std::string>;
+        auto compile(const std::unordered_map<uint32_t, std::string>& shader_sources) -> void;
+
+        uint32_t    m_renderer_id = 0;
+        std::string m_name;
+        // True when loaded from a Slang-compiled GLSL. Slang expects row-major
+        // matrix data, so matrix uniforms are transposed on upload (glm is
+        // column-major) to keep all matrix math correct.
+        bool        m_is_slang = false;
+    };
+
+    class ShaderLibrary
+    {
+    public:
+        auto add(const Ref<Shader>& shader) -> void;
+        auto add(const std::string& name, const Ref<Shader>& shader) -> void;
+        auto load(const std::string& filepath) -> Ref<Shader>;
+        auto load(const std::string& name, const std::string& filepath) -> Ref<Shader>;
+
+        auto Get(const std::string& name) -> Ref<Shader>;
+
+        auto exists(const std::string& name) const -> bool;
+    private:
+        std::unordered_map<std::string, Ref<Shader>> m_shaders;
+    };
+};
diff --git a/src/platform/opengl/texture.cpp b/src/platform/opengl/texture.cpp
new file mode 100644
index 0000000..12e07f1
--- /dev/null
+++ b/src/platform/opengl/texture.cpp
@@ -0,0 +1,296 @@
+#include "texture.h"
+
+#include "shader.h"
+#include "core/log.h"
+
+#include <glad/glad.h>
+
+#define STB_IMAGE_IMPLEMENTATION
+#include "stb_image.h"
+#include <glm/glm.hpp>
+#include <glm/gtc/matrix_transform.hpp>
+#include <glm/gtc/type_ptr.hpp>
+
+// NOTE: This file targets OpenGL 4.1 (the maximum macOS exposes). It uses the
+// classic bind-based texture API rather than 4.5 Direct State Access
+// (glCreateTextures / glTextureStorage2D / glTextureParameteri / glBindTextureUnit),
+// none of which exist on macOS. It also hosts the single STB_IMAGE_IMPLEMENTATION
+// for the whole build (the Vulkan backend links stbi_loadf from here too).
+
+namespace Donut
+{
+    Texture2D::Texture2D(uint32_t width, uint32_t height)
+        : m_width(width), m_height(height)
+    {
+        m_internal_format = GL_RGBA8;
+        m_data_format     = GL_RGBA;
+
+        glGenTextures(1, &m_renderer_id);
+        glBindTexture(GL_TEXTURE_2D, m_renderer_id);
+        glTexImage2D(GL_TEXTURE_2D, 0, m_internal_format, m_width, m_height, 0, m_data_format, GL_UNSIGNED_BYTE, nullptr);
+
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+    }
+
+    Texture2D::Texture2D(const std::string& path)
+        : m_path(path)
+    {
+        m_width          = 1;
+        m_height         = 1;
+        m_internal_format = GL_RGBA8;
+        m_data_format     = GL_RGBA;
+
+        glGenTextures(1, &m_renderer_id);
+        glBindTexture(GL_TEXTURE_2D, m_renderer_id);
+        glTexImage2D(GL_TEXTURE_2D, 0, m_internal_format, m_width, m_height, 0, m_data_format, GL_UNSIGNED_BYTE, nullptr);
+
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);
+
+        uint32_t white_pixel = 0xFFFFFFFF;
+        glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, m_width, m_height, m_data_format, GL_UNSIGNED_BYTE, &white_pixel);
+
+        DONUT_INFO("Created default texture (stb_image not available for loading: ", path, ")");
+    }
+
+    Texture2D::~Texture2D()
+    {
+        glDeleteTextures(1, &m_renderer_id);
+    }
+
+    auto Texture2D::set_data(void* data, uint32_t size) -> void
+    {
+        uint32_t bpp = m_data_format == GL_RGBA ? 4 : 3;
+        if (size != m_width * m_height * bpp)
+        {
+            DONUT_ERROR("Data must be entire texture!");
+            return;
+        }
+
+        glBindTexture(GL_TEXTURE_2D, m_renderer_id);
+        glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, m_width, m_height, m_data_format, GL_UNSIGNED_BYTE, data);
+    }
+
+    auto Texture2D::bind(uint32_t slot) const -> void
+    {
+        glActiveTexture(GL_TEXTURE0 + slot);
+        glBindTexture(GL_TEXTURE_2D, m_renderer_id);
+    }
+
+    auto Texture2D::bind_as_image(uint32_t slot, bool read_only) const -> void
+    {
+        // Image load/store is OpenGL 4.2 and unavailable on macOS. Guard the
+        // function pointer so this degrades to a no-op instead of crashing.
+        if (glBindImageTexture == nullptr)
+            return;
+        GLenum access = read_only ? GL_READ_ONLY : GL_WRITE_ONLY;
+        glBindImageTexture(slot, m_renderer_id, 0, GL_FALSE, 0, access, m_internal_format);
+    }
+
+    CubemapTexture::CubemapTexture(uint32_t width, uint32_t height)
+        : m_width(width), m_height(height)
+    {
+        m_internal_format = GL_RGBA16F;
+        m_data_format     = GL_RGBA;
+
+        glGenTextures(1, &m_renderer_id);
+        glBindTexture(GL_TEXTURE_CUBE_MAP, m_renderer_id);
+        for (uint32_t i = 0; i < 6; ++i)
+            glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, m_internal_format, m_width, m_height, 0, m_data_format, GL_FLOAT, nullptr);
+
+        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+    }
+
+    CubemapTexture::CubemapTexture(const std::string& path)
+        : m_path(path)
+    {
+        m_width          = 1024;
+        m_height         = 1024;
+        m_internal_format = GL_RGBA16F;
+        m_data_format     = GL_RGBA;
+
+        glGenTextures(1, &m_renderer_id);
+        glBindTexture(GL_TEXTURE_CUBE_MAP, m_renderer_id);
+        for (uint32_t i = 0; i < 6; ++i)
+            glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, m_internal_format, m_width, m_height, 0, m_data_format, GL_FLOAT, nullptr);
+
+        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+        glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+
+        LoadHDRI(path);
+    }
+
+    CubemapTexture::~CubemapTexture()
+    {
+        glDeleteTextures(1, &m_renderer_id);
+    }
+
+    auto CubemapTexture::LoadHDRI(const std::string& path) -> void
+    {
+        stbi_set_flip_vertically_on_load(true);
+        int width, height, channels;
+        float* hdr_data = stbi_loadf(path.c_str(), &width, &height, &channels, 3);
+
+        if (!hdr_data)
+        {
+            DONUT_ERROR("Failed to load HDRI: {}", path);
+            float default_sky[6 * 4] =
+            {
+                0.5f, 0.7f, 1.0f, 1.0f,  // Right
+                0.5f, 0.7f, 1.0f, 1.0f,  // Left
+                0.5f, 0.7f, 1.0f, 1.0f,  // Top
+                0.5f, 0.7f, 1.0f, 1.0f,  // Bottom
+                0.5f, 0.7f, 1.0f, 1.0f,  // Front
+                0.5f, 0.7f, 1.0f, 1.0f   // Back
+            };
+
+            glBindTexture(GL_TEXTURE_CUBE_MAP, m_renderer_id);
+            for (int i = 0; i < 6; ++i)
+                glTexSubImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, 0, 0, 0, 1, 1, GL_RGBA, GL_FLOAT, &default_sky[i * 4]);
+            return;
+        }
+
+        convert_equirectangular_to_cubemap(hdr_data, width, height);
+        stbi_image_free(hdr_data);
+
+        DONUT_INFO("Successfully loaded HDRI: {} ({}x{})", path, width, height);
+    }
+
+    auto CubemapTexture::convert_equirectangular_to_cubemap(float* hdr_data, int width, int height) -> void
+    {
+        uint32_t capture_fbo, capture_rbo;
+        glGenFramebuffers(1, &capture_fbo);
+        glGenRenderbuffers(1, &capture_rbo);
+
+        glBindFramebuffer(GL_FRAMEBUFFER, capture_fbo);
+        glBindRenderbuffer(GL_RENDERBUFFER, capture_rbo);
+        glRenderbufferStorage(GL_RENDERBUFFER, GL_DEPTH_COMPONENT24, m_width, m_height);
+        glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, capture_rbo);
+
+        uint32_t hdr_texture;
+        glGenTextures(1, &hdr_texture);
+        glBindTexture(GL_TEXTURE_2D, hdr_texture);
+        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB16F, width, height, 0, GL_RGB, GL_FLOAT, hdr_data);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+
+        auto equirect_shader = Shader::create("assets/shaders/EquirectToCubemap.glsl");
+        if (!equirect_shader)
+        {
+            DONUT_ERROR("Failed to create equirectangular to cubemap shader");
+            return;
+        }
+
+        uint32_t shader_program = equirect_shader->get_renderer_id();
+
+        float vertices[] =
+        {
+            -1.0f,  1.0f, -1.0f, -1.0f, -1.0f, -1.0f,  1.0f, -1.0f, -1.0f,  1.0f, -1.0f, -1.0f,  1.0f,  1.0f, -1.0f, -1.0f,  1.0f, -1.0f,
+            -1.0f, -1.0f,  1.0f, -1.0f, -1.0f, -1.0f, -1.0f,  1.0f, -1.0f, -1.0f,  1.0f, -1.0f, -1.0f,  1.0f,  1.0f, -1.0f, -1.0f,  1.0f,
+             1.0f, -1.0f, -1.0f,  1.0f, -1.0f,  1.0f,  1.0f,  1.0f,  1.0f,  1.0f,  1.0f,  1.0f,  1.0f,  1.0f, -1.0f,  1.0f, -1.0f, -1.0f,
+            -1.0f, -1.0f,  1.0f, -1.0f,  1.0f,  1.0f,  1.0f,  1.0f,  1.0f,  1.0f,  1.0f,  1.0f,  1.0f, -1.0f,  1.0f, -1.0f, -1.0f,  1.0f,
+            -1.0f,  1.0f, -1.0f,  1.0f,  1.0f, -1.0f,  1.0f,  1.0f,  1.0f,  1.0f,  1.0f,  1.0f, -1.0f,  1.0f,  1.0f, -1.0f,  1.0f, -1.0f,
+            -1.0f, -1.0f, -1.0f, -1.0f, -1.0f,  1.0f,  1.0f, -1.0f, -1.0f,  1.0f, -1.0f, -1.0f,  1.0f, -1.0f,  1.0f, -1.0f, -1.0f,  1.0f
+        };
+
+        uint32_t cube_vao, cube_vbo;
+        glGenVertexArrays(1, &cube_vao);
+        glGenBuffers(1, &cube_vbo);
+        glBindVertexArray(cube_vao);
+        glBindBuffer(GL_ARRAY_BUFFER, cube_vbo);
+        glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
+        glEnableVertexAttribArray(0);
+        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void*)0);
+
+        glm::mat4 capture_projection = glm::perspective(glm::radians(90.0f), 1.0f, 0.1f, 10.0f);
+        glm::mat4 capture_views[] =
+        {
+            glm::lookAt(glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3( 1.0f,  0.0f,  0.0f), glm::vec3(0.0f, -1.0f,  0.0f)),
+            glm::lookAt(glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(-1.0f,  0.0f,  0.0f), glm::vec3(0.0f, -1.0f,  0.0f)),
+            glm::lookAt(glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3( 0.0f,  1.0f,  0.0f), glm::vec3(0.0f,  0.0f,  1.0f)),
+            glm::lookAt(glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3( 0.0f, -1.0f,  0.0f), glm::vec3(0.0f,  0.0f, -1.0f)),
+            glm::lookAt(glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3( 0.0f,  0.0f,  1.0f), glm::vec3(0.0f, -1.0f,  0.0f)),
+            glm::lookAt(glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3( 0.0f,  0.0f, -1.0f), glm::vec3(0.0f, -1.0f,  0.0f))
+        };
+
+        glUseProgram(shader_program);
+        glUniform1i(glGetUniformLocation(shader_program, "u_EquirectangularMap"), 0);
+        // EquirectToCubemap is authored in Slang (row-major); transpose glm's
+        // column-major matrices on upload (GL_TRUE) to match.
+        glUniformMatrix4fv(glGetUniformLocation(shader_program, "u_Projection"), 1, GL_TRUE, &capture_projection[0][0]);
+        glActiveTexture(GL_TEXTURE0);
+        glBindTexture(GL_TEXTURE_2D, hdr_texture);
+
+        glViewport(0, 0, m_width, m_height);
+        glBindFramebuffer(GL_FRAMEBUFFER, capture_fbo);
+        for (unsigned int i = 0; i < 6; ++i)
+        {
+            glUniformMatrix4fv(glGetUniformLocation(shader_program, "u_View"), 1, GL_TRUE, &capture_views[i][0][0]);
+            glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_CUBE_MAP_POSITIVE_X + i, m_renderer_id, 0);
+            glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
+            glBindVertexArray(cube_vao);
+            glDrawArrays(GL_TRIANGLES, 0, 36);
+        }
+        glBindVertexArray(0);
+        glBindFramebuffer(GL_FRAMEBUFFER, 0);
+
+        glDeleteVertexArrays(1, &cube_vao);
+        glDeleteBuffers(1, &cube_vbo);
+        glDeleteTextures(1, &hdr_texture);
+        glDeleteFramebuffers(1, &capture_fbo);
+        glDeleteRenderbuffers(1, &capture_rbo);
+    }
+
+    auto CubemapTexture::set_data(void* data, uint32_t size) -> void
+    {
+        DONUT_WARN("set_data not implemented for cubemaps");
+    }
+
+    auto CubemapTexture::bind(uint32_t slot) const -> void
+    {
+        glActiveTexture(GL_TEXTURE0 + slot);
+        glBindTexture(GL_TEXTURE_CUBE_MAP, m_renderer_id);
+    }
+
+    auto CubemapTexture::bind_as_image(uint32_t slot, bool read_only) const -> void
+    {
+        if (glBindImageTexture == nullptr)
+            return;
+        GLenum access = read_only ? GL_READ_ONLY : GL_WRITE_ONLY;
+        glBindImageTexture(slot, m_renderer_id, 0, GL_TRUE, 0, access, m_internal_format);
+    }
+
+    auto Texture2D::create(uint32_t width, uint32_t height) -> Ref<Texture2D>
+    {
+        return create_ref<Texture2D>(width, height);
+    }
+
+    auto Texture2D::create(const std::string& path) -> Ref<Texture2D>
+    {
+        return create_ref<Texture2D>(path);
+    }
+
+    auto CubemapTexture::create(uint32_t width, uint32_t height) -> Ref<CubemapTexture>
+    {
+        return create_ref<CubemapTexture>(width, height);
+    }
+
+    auto CubemapTexture::create_from_hdri(const std::string& path) -> Ref<CubemapTexture>
+    {
+        return create_ref<CubemapTexture>(path);
+    }
+};
diff --git a/src/platform/opengl/texture.h b/src/platform/opengl/texture.h
new file mode 100644
index 0000000..5f68c78
--- /dev/null
+++ b/src/platform/opengl/texture.h
@@ -0,0 +1,83 @@
+#pragma once
+
+#include "core/memory.h"
+
+#include <string>
+#include <cstdint>
+#include <glm/glm.hpp>
+
+namespace Donut
+{
+    class Texture
+    {
+    public:
+        virtual ~Texture() = default;
+
+        virtual auto get_width() const -> uint32_t = 0;
+        virtual auto get_height() const -> uint32_t = 0;
+        virtual auto get_renderer_id() const -> uint32_t = 0;
+
+        virtual auto set_data(void* data, uint32_t size) -> void = 0;
+        virtual auto bind(uint32_t slot = 0) const -> void = 0;
+        virtual auto bind_as_image(uint32_t slot = 0, bool read_only = false) const -> void = 0;
+
+        virtual auto operator==(const Texture& other) const -> bool = 0;
+    };
+
+    class Texture2D : public Texture
+    {
+    public:
+        Texture2D(uint32_t width, uint32_t height);
+        Texture2D(const std::string& path);
+        ~Texture2D();
+
+        auto get_width() const -> uint32_t override { return m_width; }
+        auto get_height() const -> uint32_t override { return m_height; }
+        auto get_renderer_id() const -> uint32_t override { return m_renderer_id; }
+
+        auto set_data(void* data, uint32_t size) -> void override;
+        auto bind(uint32_t slot = 0) const -> void override;
+        auto bind_as_image(uint32_t slot = 0, bool read_only = false) const -> void override;
+
+        auto operator==(const Texture& other) const -> bool override { return m_renderer_id == other.get_renderer_id(); }
+
+        static auto create(uint32_t width, uint32_t height) -> Ref<Texture2D>;
+        static auto create(const std::string& path) -> Ref<Texture2D>;
+
+    private:
+        std::string m_path;
+        uint32_t    m_width = 0, m_height = 0;
+        uint32_t    m_renderer_id = 0;
+        uint32_t    m_internal_format = 0, m_data_format = 0; // GLenum values
+    };
+
+    class CubemapTexture : public Texture
+    {
+    public:
+        CubemapTexture(uint32_t width, uint32_t height);
+        CubemapTexture(const std::string& path);
+        ~CubemapTexture();
+
+        auto get_width() const -> uint32_t override { return m_width; }
+        auto get_height() const -> uint32_t override { return m_height; }
+        auto get_renderer_id() const -> uint32_t override { return m_renderer_id; }
+
+        auto set_data(void* data, uint32_t size) -> void override;
+        auto bind(uint32_t slot = 0) const -> void override;
+        auto bind_as_image(uint32_t slot = 0, bool read_only = false) const -> void override;
+
+        auto operator==(const Texture& other) const -> bool override { return m_renderer_id == other.get_renderer_id(); }
+
+        static auto create(uint32_t width, uint32_t height) -> Ref<CubemapTexture>;
+        static auto create_from_hdri(const std::string& path) -> Ref<CubemapTexture>;
+
+    private:
+        auto LoadHDRI(const std::string& path) -> void;
+        auto convert_equirectangular_to_cubemap(float* hdr_data, int width, int height) -> void;
+
+        std::string m_path;
+        uint32_t    m_width = 0, m_height = 0;
+        uint32_t    m_renderer_id = 0;
+        uint32_t    m_internal_format = 0, m_data_format = 0; // GLenum values
+    };
+};