feat: frame exporting

4 files changed, 282 insertions, 0 deletions

diff --git a/src/platform/opengl/opengl_framebuffer.cpp b/src/platform/opengl/opengl_framebuffer.cpp
new file mode 100644
index 0000000..c5b8fe2
--- /dev/null
+++ b/src/platform/opengl/opengl_framebuffer.cpp
@@ -0,0 +1,237 @@
+#include "opengl_framebuffer.h"
+#include "core/log.h"
+
+#include <glad/glad.h>
+
+namespace Donut
+{
+    namespace Utils
+    {
+        static GLenum texture_target(bool multisampled)
+        {
+            return multisampled ? GL_TEXTURE_2D_MULTISAMPLE : GL_TEXTURE_2D;
+        }
+
+        static void bind_texture(bool multisampled, uint32_t id)
+        {
+            glBindTexture(texture_target(multisampled), id);
+        }
+
+        static void create_textures(bool multisampled, uint32_t* out_id, uint32_t count)
+        {
+            glCreateTextures(texture_target(multisampled), count, out_id);
+        }
+
+        static void attach_color_texture(uint32_t id, int samples, GLenum internal_format, GLenum format, uint32_t width, uint32_t height, int index)
+        {
+            bool multisampled = samples > 1;
+            if (multisampled)
+            {
+                glTexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, samples, internal_format, width, height, GL_FALSE);
+            }
+            else
+            {
+                glTexImage2D(GL_TEXTURE_2D, 0, internal_format, width, height, 0, 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_R, GL_CLAMP_TO_EDGE);
+                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+            }
+
+            glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0 + index, texture_target(multisampled), id, 0);
+        }
+
+        static void attach_depth_texture(uint32_t id, int samples, GLenum format, GLenum attachment_type, uint32_t width, uint32_t height)
+        {
+            bool multisampled = samples > 1;
+            if (multisampled)
+            {
+                glTexImage2DMultisample(GL_TEXTURE_2D_MULTISAMPLE, samples, format, width, height, GL_FALSE);
+            }
+            else
+            {
+                glTexStorage2D(GL_TEXTURE_2D, 1, format, width, height);
+
+                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_R, GL_CLAMP_TO_EDGE);
+                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
+                glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+            }
+
+            glFramebufferTexture2D(GL_FRAMEBUFFER, attachment_type, texture_target(multisampled), id, 0);
+        }
+
+        static bool is_depth_format(FramebufferTextureFormat format)
+        {
+            switch (format)
+            {
+                case FramebufferTextureFormat::DEPTH24STENCIL8:  return true;
+            }
+            return false;
+        }
+
+        static GLenum donut_fb_texture_format_to_gl(FramebufferTextureFormat format)
+        {
+            switch (format)
+            {
+                case FramebufferTextureFormat::RGBA8:       return GL_RGBA8;
+                case FramebufferTextureFormat::RED_INTEGER: return GL_RED_INTEGER;
+            }
+
+            return 0;
+        }
+    }
+
+    OpenGLFramebuffer::OpenGLFramebuffer(const FramebufferSpecification& spec)
+        : m_specification(spec)
+    {
+        for (auto spec : m_specification.attachments.attachments)
+        {
+            if (!Utils::is_depth_format(spec.texture_format))
+                m_color_attachment_specifications.emplace_back(spec);
+            else
+                m_depth_attachment_specification = spec;
+        }
+
+        invalidate();
+    }
+
+    OpenGLFramebuffer::~OpenGLFramebuffer()
+    {
+        glDeleteFramebuffers(1, &m_renderer_id);
+        glDeleteTextures(static_cast<GLsizei>(m_color_attachments.size()), m_color_attachments.data());
+        glDeleteTextures(1, &m_depth_attachment);
+    }
+
+    void OpenGLFramebuffer::invalidate()
+    {
+        if (m_renderer_id)
+        {
+            glDeleteFramebuffers(1, &m_renderer_id);
+            glDeleteTextures(static_cast<GLsizei>(m_color_attachments.size()), m_color_attachments.data());
+            glDeleteTextures(1, &m_depth_attachment);
+
+            m_color_attachments.clear();
+            m_depth_attachment = 0;
+        }
+
+        glCreateFramebuffers(1, &m_renderer_id);
+        glBindFramebuffer(GL_FRAMEBUFFER, m_renderer_id);
+
+        bool multisample = m_specification.Samples > 1;
+
+        if (m_color_attachment_specifications.size())
+        {
+            m_color_attachments.resize(m_color_attachment_specifications.size());
+            Utils::create_textures(multisample, m_color_attachments.data(), static_cast<uint32_t>(m_color_attachments.size()));
+
+            for (size_t i = 0; i < m_color_attachments.size(); i++)
+            {
+                Utils::bind_texture(multisample, m_color_attachments[i]);
+                switch (m_color_attachment_specifications[i].texture_format)
+                {
+                    case FramebufferTextureFormat::RGBA8:
+                        Utils::attach_color_texture(m_color_attachments[i], m_specification.Samples, GL_RGBA8, GL_RGBA, m_specification.Width, m_specification.Height, static_cast<int>(i));
+                        break;
+                    case FramebufferTextureFormat::RED_INTEGER:
+                        Utils::attach_color_texture(m_color_attachments[i], m_specification.Samples, GL_R32I, GL_RED_INTEGER, m_specification.Width, m_specification.Height, static_cast<int>(i));
+                        break;
+                }
+            }
+        }
+
+        if (m_depth_attachment_specification.texture_format != FramebufferTextureFormat::None)
+        {
+            Utils::create_textures(multisample, &m_depth_attachment, 1);
+            Utils::bind_texture(multisample, m_depth_attachment);
+            switch (m_depth_attachment_specification.texture_format)
+            {
+                case FramebufferTextureFormat::DEPTH24STENCIL8:
+                    Utils::attach_depth_texture(m_depth_attachment, m_specification.Samples, GL_DEPTH24_STENCIL8, GL_DEPTH_STENCIL_ATTACHMENT, m_specification.Width, m_specification.Height);
+                    break;
+            }
+        }
+
+        if (m_color_attachments.size() > 1)
+        {
+            GLenum buffers[4] = { GL_COLOR_ATTACHMENT0, GL_COLOR_ATTACHMENT1, GL_COLOR_ATTACHMENT2, GL_COLOR_ATTACHMENT3 };
+            glDrawBuffers(static_cast<GLsizei>(m_color_attachments.size()), buffers);
+        }
+        else if (m_color_attachments.empty())
+            glDrawBuffer(GL_NONE);
+
+        if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
+        {
+            GLenum status = glCheckFramebufferStatus(GL_FRAMEBUFFER);
+            switch (status)
+            {
+                case GL_FRAMEBUFFER_UNDEFINED:
+                    DONUT_ERROR("Framebuffer is undefined");
+                    break;
+                case GL_FRAMEBUFFER_INCOMPLETE_ATTACHMENT:
+                    DONUT_ERROR("Framebuffer has incomplete attachment");
+                    break;
+                case GL_FRAMEBUFFER_INCOMPLETE_MISSING_ATTACHMENT:
+                    DONUT_ERROR("Framebuffer is missing attachment");
+                    break;
+                case GL_FRAMEBUFFER_INCOMPLETE_DRAW_BUFFER:
+                    DONUT_ERROR("Framebuffer has incomplete draw buffer");
+                    break;
+                case GL_FRAMEBUFFER_INCOMPLETE_READ_BUFFER:
+                    DONUT_ERROR("Framebuffer has incomplete read buffer");
+                    break;
+                case GL_FRAMEBUFFER_UNSUPPORTED:
+                    DONUT_ERROR("Framebuffer format is unsupported");
+                    break;
+                case GL_FRAMEBUFFER_INCOMPLETE_MULTISAMPLE:
+                    DONUT_ERROR("Framebuffer has incomplete multisample");
+                    break;
+                case GL_FRAMEBUFFER_INCOMPLETE_LAYER_TARGETS:
+                    DONUT_ERROR("Framebuffer has incomplete layer targets");
+                    break;
+                default:
+                    DONUT_ERROR("Framebuffer is incomplete (unknown error: {})", status);
+                    break;
+            }
+        }
+
+        glBindFramebuffer(GL_FRAMEBUFFER, 0);
+    }
+
+    void OpenGLFramebuffer::bind()
+    {
+        glBindFramebuffer(GL_FRAMEBUFFER, m_renderer_id);
+        glViewport(0, 0, m_specification.Width, m_specification.Height);
+    }
+
+    void OpenGLFramebuffer::unbind()
+    {
+        glBindFramebuffer(GL_FRAMEBUFFER, 0);
+    }
+
+    void OpenGLFramebuffer::resize(uint32_t width, uint32_t height)
+    {
+        m_specification.Width = width;
+        m_specification.Height = height;
+
+        invalidate();
+    }
+
+    int OpenGLFramebuffer::read_pixel(uint32_t attachment_index, int x, int y)
+    {
+        glReadBuffer(GL_COLOR_ATTACHMENT0 + attachment_index);
+        int pixel_data;
+        glReadPixels(x, y, 1, 1, GL_RED_INTEGER, GL_INT, &pixel_data);
+        return pixel_data;
+    }
+
+    void OpenGLFramebuffer::clear_attachment(uint32_t attachment_index, int value)
+    {
+        auto& spec = m_color_attachment_specifications[attachment_index];
+        glClearTexImage(m_color_attachments[attachment_index], 0,
+            Utils::donut_fb_texture_format_to_gl(spec.texture_format), GL_INT, &value);
+    }
+};
diff --git a/src/platform/opengl/opengl_framebuffer.h b/src/platform/opengl/opengl_framebuffer.h
new file mode 100644
index 0000000..7b07ddd
--- /dev/null
+++ b/src/platform/opengl/opengl_framebuffer.h
@@ -0,0 +1,35 @@
+#pragma once
+
+#include "rendering/framebuffer.h"
+
+namespace Donut
+{
+    class OpenGLFramebuffer : public Framebuffer
+    {
+    public:
+        OpenGLFramebuffer(const FramebufferSpecification& spec);
+        virtual ~OpenGLFramebuffer();
+
+        void invalidate();
+
+        virtual void bind()   override;
+        virtual void unbind() override;
+
+        virtual void resize(uint32_t width, uint32_t height)          override;
+        virtual int read_pixel(uint32_t attachment_index, int x, int y) override;
+
+        virtual void clear_attachment(uint32_t attachment_index, int value) override;
+        virtual uint32_t get_color_attachment_renderer_id(uint32_t index = 0) const override { return m_color_attachments[index]; }
+
+        virtual const FramebufferSpecification& get_specification() const override { return m_specification; }
+    private:
+        uint32_t m_renderer_id = 0;
+        FramebufferSpecification m_specification;
+
+        std::vector<FramebufferTextureSpecification> m_color_attachment_specifications;
+        FramebufferTextureSpecification m_depth_attachment_specification = FramebufferTextureFormat::None;
+
+        std::vector<uint32_t> m_color_attachments;
+        uint32_t m_depth_attachment = 0;
+    };
+};
diff --git a/src/platform/opengl/opengl_renderer_api.cpp b/src/platform/opengl/opengl_renderer_api.cpp
index bfb79ac..0012911 100644
--- a/src/platform/opengl/opengl_renderer_api.cpp
+++ b/src/platform/opengl/opengl_renderer_api.cpp
@@ -106,4 +106,10 @@ namespace Donut
         glBindImageTexture(slot, texture_id, 0, GL_FALSE, 0, 
                           read_only ? GL_READ_ONLY : GL_WRITE_ONLY, GL_RGBA8);
     }
+
+    void OpenGLRendererAPI::read_pixels(uint32_t x, uint32_t y, uint32_t width, uint32_t height, 
+                                       uint32_t format, uint32_t type, void* pixels)
+    {
+        glReadPixels(x, y, width, height, format, type, pixels);
+    }
 };
diff --git a/src/platform/opengl/opengl_renderer_api.h b/src/platform/opengl/opengl_renderer_api.h
index 45e6a7b..51985e0 100644
--- a/src/platform/opengl/opengl_renderer_api.h
+++ b/src/platform/opengl/opengl_renderer_api.h
@@ -36,5 +36,9 @@ namespace Donut
         virtual void bind_image_texture(uint32_t texture_id, 
                                       uint32_t slot = 0, 
                                       bool read_only = false)      override;
+        virtual void read_pixels(uint32_t x, uint32_t y, 
+                                uint32_t width,  uint32_t height, 
+                                uint32_t format, uint32_t type, 
+                                void* pixels)                     override;
     };
 };