3 files changed, 212 insertions, 0 deletions

diff --git a/src/platform/opengl/opengl_shader.h b/src/platform/opengl/opengl_shader.h
index 6b1ceec..71e20a5 100644
--- a/src/platform/opengl/opengl_shader.h
+++ b/src/platform/opengl/opengl_shader.h
@@ -32,6 +32,7 @@ namespace Donut
         virtual void memory_barrier(uint32_t barriers)                     override;
 
         virtual const std::string& get_name() const override { return m_name; }
+        virtual uint32_t get_renderer_id() const override { return m_renderer_id; }
 
         void upload_uniform_int(     const std::string& name, int value);
         void upload_uniform_int_array(const std::string& name, int* values, uint32_t count);
diff --git a/src/platform/opengl/opengl_texture.cpp b/src/platform/opengl/opengl_texture.cpp
index 5d05fb4..14ae214 100644
--- a/src/platform/opengl/opengl_texture.cpp
+++ b/src/platform/opengl/opengl_texture.cpp
@@ -1,5 +1,13 @@
 #include "opengl_texture.h"
 
+#include "rendering/shader.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>
+
 namespace Donut
 {
     OpenGLTexture2D::OpenGLTexture2D(uint32_t width, uint32_t height)
@@ -68,4 +76,176 @@ namespace Donut
         GLenum access = read_only ? GL_READ_ONLY : GL_WRITE_ONLY;
         glBindImageTexture(slot, m_renderer_id, 0, GL_FALSE, 0, access, m_internal_format);
     }
+
+    OpenGLCubemapTexture::OpenGLCubemapTexture(uint32_t width, uint32_t height)
+        : m_width(width), m_height(height)
+    {
+        m_internal_format = GL_RGB16F;
+        m_data_format     = GL_RGB;
+
+        glCreateTextures(GL_TEXTURE_CUBE_MAP, 1, &m_renderer_id);
+        glTextureStorage2D(m_renderer_id, 1, m_internal_format, m_width, m_height);
+
+        glTextureParameteri(m_renderer_id, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTextureParameteri(m_renderer_id, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+        glTextureParameteri(m_renderer_id, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+        glTextureParameteri(m_renderer_id, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+        glTextureParameteri(m_renderer_id, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+    }
+
+    OpenGLCubemapTexture::OpenGLCubemapTexture(const std::string& path)
+        : m_path(path)
+    {
+        m_width          = 1024;
+        m_height         = 1024;
+        m_internal_format = GL_RGB16F;
+        m_data_format     = GL_RGB;
+
+        glCreateTextures(GL_TEXTURE_CUBE_MAP, 1, &m_renderer_id);
+        glTextureStorage2D(m_renderer_id, 1, m_internal_format, m_width, m_height);
+
+        glTextureParameteri(m_renderer_id, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
+        glTextureParameteri(m_renderer_id, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
+        glTextureParameteri(m_renderer_id, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+        glTextureParameteri(m_renderer_id, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+        glTextureParameteri(m_renderer_id, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
+
+        load_hdri(path);
+    }
+
+    OpenGLCubemapTexture::~OpenGLCubemapTexture()
+    {
+        glDeleteTextures(1, &m_renderer_id);
+    }
+
+    void OpenGLCubemapTexture::load_hdri(const std::string& path)
+    {
+        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,
+                0.5f, 0.7f, 1.0f, 1.0f,
+                0.5f, 0.7f, 1.0f, 1.0f,
+                0.5f, 0.7f, 1.0f, 1.0f,
+                0.5f, 0.7f, 1.0f, 1.0f,
+                0.5f, 0.7f, 1.0f, 1.0f
+            };
+            
+            for (int i = 0; i < 6; ++i)
+                glTextureSubImage3D(m_renderer_id, 0, 0, 0, i, 1, 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);
+    }
+
+    void OpenGLCubemapTexture::convert_equirectangular_to_cubemap(float* hdr_data, int width, int height)
+    {
+        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/equirect_to_cubemap.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, "equirectangularMap"), 0);
+        glUniformMatrix4fv(glGetUniformLocation(shader_program, "projection"), 1, GL_FALSE, &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, "view"), 1, GL_FALSE, &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);
+
+        glDeleteVertexArrays(1, &cube_vao);
+        glDeleteBuffers(1, &cube_vbo);
+        glDeleteProgram(shader_program);
+        glDeleteTextures(1, &hdr_texture);
+        glDeleteFramebuffers(1, &capture_fbo);
+        glDeleteRenderbuffers(1, &capture_rbo);
+    }
+
+    void OpenGLCubemapTexture::set_data(void* data, uint32_t size)
+    {
+        DONUT_WARN("SetData not implemented for cubemaps");
+    }
+
+    void OpenGLCubemapTexture::bind(uint32_t slot) const
+    {
+        glBindTextureUnit(slot, m_renderer_id);
+    }
+
+    void OpenGLCubemapTexture::bind_as_image(uint32_t slot, bool read_only) const
+    {
+        GLenum access = read_only ? GL_READ_ONLY : GL_WRITE_ONLY;
+        glBindImageTexture(slot, m_renderer_id, 0, GL_TRUE, 0, access, m_internal_format);
+    }
 };
diff --git a/src/platform/opengl/opengl_texture.h b/src/platform/opengl/opengl_texture.h
index 705d770..5e5f6b2 100644
--- a/src/platform/opengl/opengl_texture.h
+++ b/src/platform/opengl/opengl_texture.h
@@ -34,4 +34,35 @@ namespace Donut
         uint32_t    m_renderer_id;
         GLenum      m_internal_format, m_data_format;
     };
+
+    class OpenGLCubemapTexture 
+        : public CubemapTexture
+    {
+    public:
+        OpenGLCubemapTexture(uint32_t width, uint32_t height);
+        OpenGLCubemapTexture(const std::string& path);
+        virtual ~OpenGLCubemapTexture();
+
+        virtual uint32_t get_width()      const override { return m_width; }
+        virtual uint32_t get_height()     const override { return m_height; }
+        virtual uint32_t get_renderer_id() const override { return m_renderer_id; }
+
+        virtual void set_data(void* data, uint32_t size)                          override;
+        virtual void bind(uint32_t slot = 0)                               const override;
+        virtual void bind_as_image(uint32_t slot = 0, bool read_only = false) const override;
+
+        virtual bool operator==(const Texture& other) const override
+        {
+            return m_renderer_id == other.get_renderer_id();
+        }
+
+    private:
+        void load_hdri(const std::string& path);
+        void convert_equirectangular_to_cubemap(float* hdr_data, int width, int height);
+
+        std::string m_path;
+        uint32_t    m_width, m_height;
+        uint32_t    m_renderer_id;
+        GLenum      m_internal_format, m_data_format;
+    };
 }