Introduce render passes

* First API design (many features missing, including input attachments)
* Metal implementation (no OpenGL yet)
* Render-to-texture demo (a little broken until we have depth buffers)
* Update examples to use render passes

src/backend/opengl/CommandBufferGL.cpp

@@ -60,6 +60,17 @@ namespace opengl {
 
         while(commands.NextCommandId(&type)) {
             switch (type) {
+                case Command::AdvanceSubpass:
+                    {
+                        // TODO(kainino@chromium.org): implement
+                    }
+                    break;
+
+                case Command::BeginRenderPass:
+                    {
+                        // TODO(kainino@chromium.org): implement
+                    }
+                    break;
 
                 case Command::CopyBufferToTexture:
                     {
@@ -124,6 +135,12 @@ namespace opengl {
                     }
                     break;
 
+                case Command::EndRenderPass:
+                    {
+                        // TODO(kainino@chromium.org): implement
+                    }
+                    break;
+
                 case Command::SetPipeline:
                     {
                         SetPipelineCmd* cmd = commands.NextCommand<SetPipelineCmd>();

src/backend/opengl/OpenGLBackend.cpp

@@ -63,6 +63,9 @@ namespace opengl {
     InputStateBase* Device::CreateInputState(InputStateBuilder* builder) {
         return new InputState(this, builder);
     }
+    FramebufferBase* Device::CreateFramebuffer(FramebufferBuilder* builder) {
+        return new Framebuffer(this, builder);
+    }
     PipelineBase* Device::CreatePipeline(PipelineBuilder* builder) {
         return new Pipeline(this, builder);
     }
@@ -72,6 +75,9 @@ namespace opengl {
     QueueBase* Device::CreateQueue(QueueBuilder* builder) {
         return new Queue(this, builder);
     }
+    RenderPassBase* Device::CreateRenderPass(RenderPassBuilder* builder) {
+        return new RenderPass(this, builder);
+    }
     SamplerBase* Device::CreateSampler(SamplerBuilder* builder) {
         return new Sampler(this, builder);
     }
@@ -165,6 +171,12 @@ namespace opengl {
         return vertexArrayObject;
     }
 
+    // Framebuffer
+
+    Framebuffer::Framebuffer(Device* device, FramebufferBuilder* builder)
+        : FramebufferBase(builder), device(device) {
+    }
+
     // Queue
 
     Queue::Queue(Device* device, QueueBuilder* builder)
@@ -177,5 +189,11 @@ namespace opengl {
         }
     }
 
+    // RenderPass
+
+    RenderPass::RenderPass(Device* device, RenderPassBuilder* builder)
+        : RenderPassBase(builder), device(device) {
+    }
+
 }
 }

src/backend/opengl/OpenGLBackend.h

@@ -21,8 +21,10 @@
 #include "common/BindGroup.h"
 #include "common/BindGroupLayout.h"
 #include "common/Device.h"
+#include "common/Framebuffer.h"
 #include "common/InputState.h"
 #include "common/Queue.h"
+#include "common/RenderPass.h"
 #include "common/ToBackend.h"
 
 #include "glad/glad.h"
@@ -43,6 +45,8 @@ namespace opengl {
     class ShaderModule;
     class Texture;
     class TextureView;
+    class Framebuffer;
+    class RenderPass;
 
     struct OpenGLBackendTraits {
         using BindGroupType = BindGroup;
@@ -58,6 +62,8 @@ namespace opengl {
         using ShaderModuleType = ShaderModule;
         using TextureType = Texture;
         using TextureViewType = TextureView;
+        using FramebufferType = Framebuffer;
+        using RenderPassType = RenderPass;
     };
 
     template<typename T>
@@ -74,9 +80,11 @@ namespace opengl {
             BufferViewBase* CreateBufferView(BufferViewBuilder* builder) override;
             CommandBufferBase* CreateCommandBuffer(CommandBufferBuilder* builder) override;
             InputStateBase* CreateInputState(InputStateBuilder* builder) override;
+            FramebufferBase* CreateFramebuffer(FramebufferBuilder* builder) override;
             PipelineBase* CreatePipeline(PipelineBuilder* builder) override;
             PipelineLayoutBase* CreatePipelineLayout(PipelineLayoutBuilder* builder) override;
             QueueBase* CreateQueue(QueueBuilder* builder) override;
+            RenderPassBase* CreateRenderPass(RenderPassBuilder* builder) override;
             SamplerBase* CreateSampler(SamplerBuilder* builder) override;
             ShaderModuleBase* CreateShaderModule(ShaderModuleBuilder* builder) override;
             TextureBase* CreateTexture(TextureBuilder* builder) override;
@@ -124,6 +132,14 @@ namespace opengl {
             Device* device;
     };
 
+    class Framebuffer : public FramebufferBase {
+        public:
+            Framebuffer(Device* device, FramebufferBuilder* builder);
+
+        private:
+            Device* device;
+    };
+
     class InputState : public InputStateBase {
         public:
             InputState(Device* device, InputStateBuilder* builder);
@@ -145,6 +161,14 @@ namespace opengl {
             Device* device;
     };
 
+    class RenderPass : public RenderPassBase {
+        public:
+            RenderPass(Device* device, RenderPassBuilder* builder);
+
+        private:
+            Device* device;
+    };
+
 }
 }