Update shader

apps/RenderCadenceCompositor/render/runtime/RuntimeRenderScene.cpp

@@ -6,6 +6,10 @@
 #include <functional>
 #include <utility>
 
+#ifndef GL_FRAMEBUFFER_BINDING
+#define GL_FRAMEBUFFER_BINDING 0x8CA6
+#endif
+
 RuntimeRenderScene::~RuntimeRenderScene()
 {
 	ShutdownGl();
@@ -90,12 +94,50 @@ void RuntimeRenderScene::RenderFrame(uint64_t frameIndex, unsigned width, unsign
 {
 	ConsumePreparedPrograms();
 
+	std::vector<LayerProgram*> readyLayers;
 	for (const std::string& layerId : mLayerOrder)
 	{
 		LayerProgram* layer = FindLayer(layerId);
 		if (!layer || !layer->renderer || !layer->renderer->HasProgram())
 			continue;
-		layer->renderer->RenderFrame(frameIndex, width, height);
+		readyLayers.push_back(layer);
+	}
+
+	if (readyLayers.empty())
+		return;
+
+	GLint outputFramebuffer = 0;
+	glGetIntegerv(GL_FRAMEBUFFER_BINDING, &outputFramebuffer);
+
+	if (readyLayers.size() == 1)
+	{
+		readyLayers.front()->renderer->RenderFrame(frameIndex, width, height);
+		return;
+	}
+
+	if (!EnsureLayerTargets(width, height))
+	{
+		glBindFramebuffer(GL_FRAMEBUFFER, static_cast<GLuint>(outputFramebuffer));
+		readyLayers.back()->renderer->RenderFrame(frameIndex, width, height);
+		return;
+	}
+
+	GLuint layerInputTexture = 0;
+	std::size_t nextTargetIndex = 0;
+	for (std::size_t layerIndex = 0; layerIndex < readyLayers.size(); ++layerIndex)
+	{
+		const bool isFinalLayer = layerIndex == readyLayers.size() - 1;
+		if (isFinalLayer)
+		{
+			glBindFramebuffer(GL_FRAMEBUFFER, static_cast<GLuint>(outputFramebuffer));
+			readyLayers[layerIndex]->renderer->RenderFrame(frameIndex, width, height, layerInputTexture, layerInputTexture);
+			continue;
+		}
+
+		glBindFramebuffer(GL_FRAMEBUFFER, mLayerFramebuffers[nextTargetIndex]);
+		readyLayers[layerIndex]->renderer->RenderFrame(frameIndex, width, height, layerInputTexture, layerInputTexture);
+		layerInputTexture = mLayerTextures[nextTargetIndex];
+		nextTargetIndex = 1 - nextTargetIndex;
 	}
 }
 
@@ -109,6 +151,7 @@ void RuntimeRenderScene::ShutdownGl()
 	}
 	mLayers.clear();
 	mLayerOrder.clear();
+	DestroyLayerTargets();
 }
 
 void RuntimeRenderScene::ConsumePreparedPrograms()
@@ -146,6 +189,68 @@ void RuntimeRenderScene::ConsumePreparedPrograms()
 	}
 }
 
+bool RuntimeRenderScene::EnsureLayerTargets(unsigned width, unsigned height)
+{
+	if (width == 0 || height == 0)
+		return false;
+	if (mLayerFramebuffers[0] != 0 && mLayerFramebuffers[1] != 0 && mLayerTextures[0] != 0 && mLayerTextures[1] != 0
+		&& mLayerTargetWidth == width && mLayerTargetHeight == height)
+		return true;
+
+	DestroyLayerTargets();
+	mLayerTargetWidth = width;
+	mLayerTargetHeight = height;
+
+	glGenFramebuffers(2, mLayerFramebuffers);
+	glGenTextures(2, mLayerTextures);
+	for (int index = 0; index < 2; ++index)
+	{
+		glBindTexture(GL_TEXTURE_2D, mLayerTextures[index]);
+		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_CLAMP_TO_EDGE);
+		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
+		glTexImage2D(
+			GL_TEXTURE_2D,
+			0,
+			GL_RGBA8,
+			static_cast<GLsizei>(width),
+			static_cast<GLsizei>(height),
+			0,
+			GL_BGRA,
+			GL_UNSIGNED_INT_8_8_8_8_REV,
+			nullptr);
+
+		glBindFramebuffer(GL_FRAMEBUFFER, mLayerFramebuffers[index]);
+		glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, mLayerTextures[index], 0);
+		if (glCheckFramebufferStatus(GL_FRAMEBUFFER) != GL_FRAMEBUFFER_COMPLETE)
+		{
+			glBindFramebuffer(GL_FRAMEBUFFER, 0);
+			glBindTexture(GL_TEXTURE_2D, 0);
+			DestroyLayerTargets();
+			return false;
+		}
+	}
+
+	glBindFramebuffer(GL_FRAMEBUFFER, 0);
+	glBindTexture(GL_TEXTURE_2D, 0);
+	return true;
+}
+
+void RuntimeRenderScene::DestroyLayerTargets()
+{
+	if (mLayerFramebuffers[0] != 0 || mLayerFramebuffers[1] != 0)
+		glDeleteFramebuffers(2, mLayerFramebuffers);
+	if (mLayerTextures[0] != 0 || mLayerTextures[1] != 0)
+		glDeleteTextures(2, mLayerTextures);
+	mLayerFramebuffers[0] = 0;
+	mLayerFramebuffers[1] = 0;
+	mLayerTextures[0] = 0;
+	mLayerTextures[1] = 0;
+	mLayerTargetWidth = 0;
+	mLayerTargetHeight = 0;
+}
+
 RuntimeRenderScene::LayerProgram* RuntimeRenderScene::FindLayer(const std::string& layerId)
 {
 	for (LayerProgram& layer : mLayers)