Multipass shaders

2026-05-12 17:08:35 +10:00
parent 1429b2e660
commit dfd49fd0e3
12 changed files with 392 additions and 72 deletions
--- a/apps/RenderCadenceCompositor/render/runtime/RuntimeRenderScene.cpp
+++ b/apps/RenderCadenceCompositor/render/runtime/RuntimeRenderScene.cpp
@@ -39,14 +39,18 @@ bool RuntimeRenderScene::CommitRenderLayers(const std::vector<RenderCadenceCompo
 			continue;
 		}

-		if (layerIt->renderer)
-			layerIt->renderer->ShutdownGl();
+		for (LayerProgram::PassProgram& pass : layerIt->passes)
+		{
+			if (pass.renderer)
+				pass.renderer->ShutdownGl();
+		}
+		ReleasePendingPrograms(*layerIt);
 		layerIt = mLayers.erase(layerIt);
 	}

 	for (const RenderCadenceCompositor::RuntimeRenderLayerModel& layer : layers)
 	{
-		if (layer.artifact.fragmentShaderSource.empty())
+		if (layer.artifact.passes.empty() && layer.artifact.fragmentShaderSource.empty())
 			continue;

 		const std::string fingerprint = Fingerprint(layer.artifact);
@@ -55,16 +59,25 @@ bool RuntimeRenderScene::CommitRenderLayers(const std::vector<RenderCadenceCompo
 		{
 			LayerProgram next;
 			next.layerId = layer.id;
-			next.renderer = std::make_unique<RuntimeShaderRenderer>();
 			mLayers.push_back(std::move(next));
 			program = &mLayers.back();
 		}

-		if (program->shaderId == layer.shaderId && program->sourceFingerprint == fingerprint && program->renderer && program->renderer->HasProgram())
+		bool hasReadyPass = false;
+		for (const LayerProgram::PassProgram& pass : program->passes)
+		{
+			if (pass.renderer && pass.renderer->HasProgram())
+			{
+				hasReadyPass = true;
+				break;
+			}
+		}
+		if (program->shaderId == layer.shaderId && program->sourceFingerprint == fingerprint && hasReadyPass)
 			continue;
 		if (program->pendingFingerprint == fingerprint)
 			continue;

+		ReleasePendingPrograms(*program);
 		program->shaderId = layer.shaderId;
 		program->pendingFingerprint = fingerprint;
 		layersToPrepare.push_back(layer);
@@ -84,8 +97,13 @@ bool RuntimeRenderScene::HasLayers()
 	for (const std::string& layerId : mLayerOrder)
 	{
 		const LayerProgram* layer = FindLayer(layerId);
-		if (layer && layer->renderer && layer->renderer->HasProgram())
-			return true;
+		if (!layer)
+			continue;
+		for (const LayerProgram::PassProgram& pass : layer->passes)
+		{
+			if (pass.renderer && pass.renderer->HasProgram())
+				return true;
+		}
 	}
 	return false;
 }
@@ -98,9 +116,16 @@ void RuntimeRenderScene::RenderFrame(uint64_t frameIndex, unsigned width, unsign
 	for (const std::string& layerId : mLayerOrder)
 	{
 		LayerProgram* layer = FindLayer(layerId);
-		if (!layer || !layer->renderer || !layer->renderer->HasProgram())
+		if (!layer)
 			continue;
-		readyLayers.push_back(layer);
+		for (const LayerProgram::PassProgram& pass : layer->passes)
+		{
+			if (pass.renderer && pass.renderer->HasProgram())
+			{
+				readyLayers.push_back(layer);
+				break;
+			}
+		}
 	}

 	if (readyLayers.empty())
@@ -111,14 +136,14 @@ void RuntimeRenderScene::RenderFrame(uint64_t frameIndex, unsigned width, unsign

 	if (readyLayers.size() == 1)
 	{
-		readyLayers.front()->renderer->RenderFrame(frameIndex, width, height);
+		RenderLayer(*readyLayers.front(), frameIndex, width, height, 0, static_cast<GLuint>(outputFramebuffer), true);
 		return;
 	}

 	if (!EnsureLayerTargets(width, height))
 	{
 		glBindFramebuffer(GL_FRAMEBUFFER, static_cast<GLuint>(outputFramebuffer));
-		readyLayers.back()->renderer->RenderFrame(frameIndex, width, height);
+		RenderLayer(*readyLayers.back(), frameIndex, width, height, 0, static_cast<GLuint>(outputFramebuffer), true);
 		return;
 	}

@@ -130,12 +155,11 @@ void RuntimeRenderScene::RenderFrame(uint64_t frameIndex, unsigned width, unsign
 		if (isFinalLayer)
 		{
 			glBindFramebuffer(GL_FRAMEBUFFER, static_cast<GLuint>(outputFramebuffer));
-			readyLayers[layerIndex]->renderer->RenderFrame(frameIndex, width, height, layerInputTexture, layerInputTexture);
+			RenderLayer(*readyLayers[layerIndex], frameIndex, width, height, layerInputTexture, static_cast<GLuint>(outputFramebuffer), true);
 			continue;
 		}

-		glBindFramebuffer(GL_FRAMEBUFFER, mLayerFramebuffers[nextTargetIndex]);
-		readyLayers[layerIndex]->renderer->RenderFrame(frameIndex, width, height, layerInputTexture, layerInputTexture);
+		RenderLayer(*readyLayers[layerIndex], frameIndex, width, height, layerInputTexture, mLayerFramebuffers[nextTargetIndex], true);
 		layerInputTexture = mLayerTextures[nextTargetIndex];
 		nextTargetIndex = 1 - nextTargetIndex;
 	}
@@ -146,8 +170,12 @@ void RuntimeRenderScene::ShutdownGl()
 	mPrepareWorker.Stop();
 	for (LayerProgram& layer : mLayers)
 	{
-		if (layer.renderer)
-			layer.renderer->ShutdownGl();
+		for (LayerProgram::PassProgram& pass : layer.passes)
+		{
+			if (pass.renderer)
+				pass.renderer->ShutdownGl();
+		}
+		ReleasePendingPrograms(layer);
 	}
 	mLayers.clear();
 	mLayerOrder.clear();
@@ -172,28 +200,165 @@ void RuntimeRenderScene::ConsumePreparedPrograms()
 			continue;
 		}

+		bool replacesExistingPendingPass = false;
+		for (RuntimePreparedShaderProgram& existing : layer->pendingPreparedPrograms)
+		{
+			if (existing.passId != preparedProgram.passId)
+				continue;
+			existing.ReleaseGl();
+			existing = std::move(preparedProgram);
+			replacesExistingPendingPass = true;
+			break;
+		}
+		if (!replacesExistingPendingPass)
+			layer->pendingPreparedPrograms.push_back(std::move(preparedProgram));
+		TryCommitPendingPrograms(*layer);
+	}
+}
+
+void RuntimeRenderScene::ReleasePendingPrograms(LayerProgram& layer)
+{
+	for (RuntimePreparedShaderProgram& program : layer.pendingPreparedPrograms)
+		program.ReleaseGl();
+	layer.pendingPreparedPrograms.clear();
+}
+
+void RuntimeRenderScene::TryCommitPendingPrograms(LayerProgram& layer)
+{
+	if (layer.pendingPreparedPrograms.empty())
+		return;
+
+	const RuntimeShaderArtifact& artifact = layer.pendingPreparedPrograms.front().artifact;
+	const std::size_t expectedPassCount = artifact.passes.empty() ? 1 : artifact.passes.size();
+	if (layer.pendingPreparedPrograms.size() < expectedPassCount)
+		return;
+
+	std::vector<LayerProgram::PassProgram> nextPasses;
+	nextPasses.reserve(expectedPassCount);
+	for (const RuntimeShaderPassArtifact& passArtifact : artifact.passes)
+	{
+		auto preparedIt = std::find_if(
+			layer.pendingPreparedPrograms.begin(),
+			layer.pendingPreparedPrograms.end(),
+			[&passArtifact](const RuntimePreparedShaderProgram& prepared) {
+				return prepared.passId == passArtifact.passId;
+			});
+		if (preparedIt == layer.pendingPreparedPrograms.end())
+			return;
+
 		std::unique_ptr<RuntimeShaderRenderer> nextRenderer = std::make_unique<RuntimeShaderRenderer>();
 		std::string error;
-		if (!nextRenderer->CommitPreparedProgram(preparedProgram, error))
+		if (!nextRenderer->CommitPreparedProgram(*preparedIt, error))
 		{
-			preparedProgram.ReleaseGl();
+			ReleasePendingPrograms(layer);
+			return;
+		}
+
+		LayerProgram::PassProgram nextPass;
+		nextPass.passId = preparedIt->passId;
+		nextPass.inputNames = preparedIt->inputNames;
+		nextPass.outputName = preparedIt->outputName.empty() ? preparedIt->passId : preparedIt->outputName;
+		nextPass.renderer = std::move(nextRenderer);
+		nextPasses.push_back(std::move(nextPass));
+	}
+	if (artifact.passes.empty())
+	{
+		RuntimePreparedShaderProgram& prepared = layer.pendingPreparedPrograms.front();
+		std::unique_ptr<RuntimeShaderRenderer> nextRenderer = std::make_unique<RuntimeShaderRenderer>();
+		std::string error;
+		if (!nextRenderer->CommitPreparedProgram(prepared, error))
+		{
+			ReleasePendingPrograms(layer);
+			return;
+		}
+
+		LayerProgram::PassProgram nextPass;
+		nextPass.passId = prepared.passId;
+		nextPass.inputNames = prepared.inputNames;
+		nextPass.outputName = prepared.outputName.empty() ? prepared.passId : prepared.outputName;
+		nextPass.renderer = std::move(nextRenderer);
+		nextPasses.push_back(std::move(nextPass));
+	}
+
+	for (LayerProgram::PassProgram& pass : layer.passes)
+	{
+		if (pass.renderer)
+			pass.renderer->ShutdownGl();
+	}
+	layer.passes = std::move(nextPasses);
+	layer.shaderId = artifact.shaderId;
+	layer.sourceFingerprint = layer.pendingPreparedPrograms.front().sourceFingerprint;
+	layer.pendingFingerprint.clear();
+	layer.pendingPreparedPrograms.clear();
+}
+
+GLuint RuntimeRenderScene::RenderLayer(
+	LayerProgram& layer,
+	uint64_t frameIndex,
+	unsigned width,
+	unsigned height,
+	GLuint layerInputTexture,
+	GLuint outputFramebuffer,
+	bool renderToOutput)
+{
+	GLuint namedOutputs[2] = {};
+	std::string namedOutputNames[2];
+	std::size_t nextTargetIndex = 2;
+	GLuint lastOutputTexture = layerInputTexture;
+
+	for (LayerProgram::PassProgram& pass : layer.passes)
+	{
+		if (!pass.renderer || !pass.renderer->HasProgram())
+			continue;
+
+		GLuint sourceTexture = layerInputTexture;
+		if (!pass.inputNames.empty())
+		{
+			const std::string& inputName = pass.inputNames.front();
+			if (inputName != "layerInput" && inputName != "videoInput")
+			{
+				for (std::size_t index = 0; index < 2; ++index)
+				{
+					if (namedOutputNames[index] == inputName)
+					{
+						sourceTexture = namedOutputs[index];
+						break;
+					}
+				}
+			}
+		}
+
+		const bool writesLayerOutput = pass.outputName == "layerOutput";
+		if (writesLayerOutput && renderToOutput)
+		{
+			glBindFramebuffer(GL_FRAMEBUFFER, outputFramebuffer);
+			pass.renderer->RenderFrame(frameIndex, width, height, sourceTexture, sourceTexture);
+			lastOutputTexture = 0;
 			continue;
 		}

-		if (layer->renderer)
-			layer->renderer->ShutdownGl();
-		layer->renderer = std::move(nextRenderer);
-		layer->shaderId = preparedProgram.shaderId;
-		layer->sourceFingerprint = preparedProgram.sourceFingerprint;
-		layer->pendingFingerprint.clear();
+		if (!EnsureLayerTargets(width, height))
+			continue;
+
+		const std::size_t targetIndex = nextTargetIndex;
+		nextTargetIndex = nextTargetIndex == 2 ? 3 : 2;
+		glBindFramebuffer(GL_FRAMEBUFFER, mLayerFramebuffers[targetIndex]);
+		pass.renderer->RenderFrame(frameIndex, width, height, sourceTexture, sourceTexture);
+		const std::size_t namedIndex = targetIndex - 2;
+		namedOutputs[namedIndex] = mLayerTextures[targetIndex];
+		namedOutputNames[namedIndex] = pass.outputName;
+		lastOutputTexture = mLayerTextures[targetIndex];
 	}
+
+	return lastOutputTexture;
 }

 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
+	if (mLayerFramebuffers[0] != 0 && mLayerFramebuffers[1] != 0 && mLayerFramebuffers[2] != 0 && mLayerFramebuffers[3] != 0
+		&& mLayerTextures[0] != 0 && mLayerTextures[1] != 0 && mLayerTextures[2] != 0 && mLayerTextures[3] != 0
 		&& mLayerTargetWidth == width && mLayerTargetHeight == height)
 		return true;

@@ -201,9 +366,9 @@ bool RuntimeRenderScene::EnsureLayerTargets(unsigned width, unsigned height)
 	mLayerTargetWidth = width;
 	mLayerTargetHeight = height;

-	glGenFramebuffers(2, mLayerFramebuffers);
-	glGenTextures(2, mLayerTextures);
-	for (int index = 0; index < 2; ++index)
+	glGenFramebuffers(4, mLayerFramebuffers);
+	glGenTextures(4, mLayerTextures);
+	for (int index = 0; index < 4; ++index)
 	{
 		glBindTexture(GL_TEXTURE_2D, mLayerTextures[index]);
 		glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
@@ -239,14 +404,15 @@ bool RuntimeRenderScene::EnsureLayerTargets(unsigned width, unsigned height)

 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;
+	if (mLayerFramebuffers[0] != 0 || mLayerFramebuffers[1] != 0 || mLayerFramebuffers[2] != 0 || mLayerFramebuffers[3] != 0)
+		glDeleteFramebuffers(4, mLayerFramebuffers);
+	if (mLayerTextures[0] != 0 || mLayerTextures[1] != 0 || mLayerTextures[2] != 0 || mLayerTextures[3] != 0)
+		glDeleteTextures(4, mLayerTextures);
+	for (int index = 0; index < 4; ++index)
+	{
+		mLayerFramebuffers[index] = 0;
+		mLayerTextures[index] = 0;
+	}
 	mLayerTargetWidth = 0;
 	mLayerTargetHeight = 0;
 }
@@ -271,8 +437,23 @@ const RuntimeRenderScene::LayerProgram* RuntimeRenderScene::FindLayer(const std:
 	return nullptr;
 }

+RuntimeRenderScene::LayerProgram::PassProgram* RuntimeRenderScene::FindPass(LayerProgram& layer, const std::string& passId)
+{
+	for (LayerProgram::PassProgram& pass : layer.passes)
+	{
+		if (pass.passId == passId)
+			return &pass;
+	}
+	return nullptr;
+}
+
 std::string RuntimeRenderScene::Fingerprint(const RuntimeShaderArtifact& artifact)
 {
 	const std::hash<std::string> hasher;
-	return artifact.shaderId + ":" + std::to_string(artifact.fragmentShaderSource.size()) + ":" + std::to_string(hasher(artifact.fragmentShaderSource));
+	std::string source;
+	for (const RuntimeShaderPassArtifact& pass : artifact.passes)
+		source += pass.passId + ":" + pass.outputName + ":" + pass.fragmentShaderSource + "\n";
+	if (source.empty())
+		source = artifact.fragmentShaderSource;
+	return artifact.shaderId + ":" + std::to_string(source.size()) + ":" + std::to_string(hasher(source));
 }
--- a/apps/RenderCadenceCompositor/render/runtime/RuntimeRenderScene.h
+++ b/apps/RenderCadenceCompositor/render/runtime/RuntimeRenderScene.h
@@ -32,21 +32,33 @@ private:
 		std::string shaderId;
 		std::string sourceFingerprint;
 		std::string pendingFingerprint;
-		std::unique_ptr<RuntimeShaderRenderer> renderer;
+		std::vector<RuntimePreparedShaderProgram> pendingPreparedPrograms;
+		struct PassProgram
+		{
+			std::string passId;
+			std::vector<std::string> inputNames;
+			std::string outputName;
+			std::unique_ptr<RuntimeShaderRenderer> renderer;
+		};
+		std::vector<PassProgram> passes;
 	};

 	void ConsumePreparedPrograms();
+	void ReleasePendingPrograms(LayerProgram& layer);
+	void TryCommitPendingPrograms(LayerProgram& layer);
 	bool EnsureLayerTargets(unsigned width, unsigned height);
 	void DestroyLayerTargets();
+	GLuint RenderLayer(LayerProgram& layer, uint64_t frameIndex, unsigned width, unsigned height, GLuint layerInputTexture, GLuint outputFramebuffer, bool renderToOutput);
 	LayerProgram* FindLayer(const std::string& layerId);
 	const LayerProgram* FindLayer(const std::string& layerId) const;
+	LayerProgram::PassProgram* FindPass(LayerProgram& layer, const std::string& passId);
 	static std::string Fingerprint(const RuntimeShaderArtifact& artifact);

 	RuntimeShaderPrepareWorker mPrepareWorker;
 	std::vector<LayerProgram> mLayers;
 	std::vector<std::string> mLayerOrder;
-	GLuint mLayerFramebuffers[2] = {};
-	GLuint mLayerTextures[2] = {};
+	GLuint mLayerFramebuffers[4] = {};
+	GLuint mLayerTextures[4] = {};
 	unsigned mLayerTargetWidth = 0;
 	unsigned mLayerTargetHeight = 0;
 };
--- a/apps/RenderCadenceCompositor/render/runtime/RuntimeShaderPrepareWorker.cpp
+++ b/apps/RenderCadenceCompositor/render/runtime/RuntimeShaderPrepareWorker.cpp
@@ -77,20 +77,35 @@ void RuntimeShaderPrepareWorker::Submit(const std::vector<RenderCadenceComposito
 	std::lock_guard<std::mutex> lock(mMutex);
 	for (const RenderCadenceCompositor::RuntimeRenderLayerModel& layer : layers)
 	{
-		if (layer.artifact.fragmentShaderSource.empty())
+		if (layer.artifact.passes.empty() && layer.artifact.fragmentShaderSource.empty())
 			continue;

-		PrepareRequest request;
-		request.layerId = layer.id;
-		request.shaderId = layer.shaderId;
-		request.sourceFingerprint = Fingerprint(layer.artifact);
-		request.artifact = layer.artifact;
+		std::vector<RuntimeShaderPassArtifact> passes = layer.artifact.passes;
+		if (passes.empty())
+		{
+			RuntimeShaderPassArtifact pass;
+			pass.passId = "main";
+			pass.fragmentShaderSource = layer.artifact.fragmentShaderSource;
+			pass.outputName = "layerOutput";
+			passes.push_back(std::move(pass));
+		}

-		auto sameLayer = [&request](const PrepareRequest& existing) {
-			return existing.layerId == request.layerId;
+		auto sameLayer = [&layer](const PrepareRequest& existing) {
+			return existing.layerId == layer.id;
 		};
 		mRequests.erase(std::remove_if(mRequests.begin(), mRequests.end(), sameLayer), mRequests.end());
-		mRequests.push_back(std::move(request));
+
+		for (const RuntimeShaderPassArtifact& pass : passes)
+		{
+			PrepareRequest request;
+			request.layerId = layer.id;
+			request.shaderId = layer.shaderId;
+			request.passId = pass.passId;
+			request.sourceFingerprint = Fingerprint(layer.artifact);
+			request.artifact = layer.artifact;
+			request.passArtifact = pass;
+			mRequests.push_back(std::move(request));
+		}
 	}
 	mCondition.notify_one();
 }
@@ -137,10 +152,11 @@ void RuntimeShaderPrepareWorker::ThreadMain()
 		}

 		RuntimePreparedShaderProgram preparedProgram;
-		RuntimeShaderRenderer::BuildPreparedProgram(
+		RuntimeShaderRenderer::BuildPreparedPassProgram(
 			request.layerId,
 			request.sourceFingerprint,
 			request.artifact,
+			request.passArtifact,
 			preparedProgram);
 		glFlush();

@@ -154,5 +170,10 @@ void RuntimeShaderPrepareWorker::ThreadMain()
 std::string RuntimeShaderPrepareWorker::Fingerprint(const RuntimeShaderArtifact& artifact)
 {
 	const std::hash<std::string> hasher;
-	return artifact.shaderId + ":" + std::to_string(artifact.fragmentShaderSource.size()) + ":" + std::to_string(hasher(artifact.fragmentShaderSource));
+	std::string source;
+	for (const RuntimeShaderPassArtifact& pass : artifact.passes)
+		source += pass.passId + ":" + pass.outputName + ":" + pass.fragmentShaderSource + "\n";
+	if (source.empty())
+		source = artifact.fragmentShaderSource;
+	return artifact.shaderId + ":" + std::to_string(source.size()) + ":" + std::to_string(hasher(source));
 }
--- a/apps/RenderCadenceCompositor/render/runtime/RuntimeShaderPrepareWorker.h
+++ b/apps/RenderCadenceCompositor/render/runtime/RuntimeShaderPrepareWorker.h
@@ -35,8 +35,10 @@ private:
 	{
 		std::string layerId;
 		std::string shaderId;
+		std::string passId;
 		std::string sourceFingerprint;
 		RuntimeShaderArtifact artifact;
+		RuntimeShaderPassArtifact passArtifact;
 	};

 	void ThreadMain();
--- a/apps/RenderCadenceCompositor/render/runtime/RuntimeShaderProgram.h
+++ b/apps/RenderCadenceCompositor/render/runtime/RuntimeShaderProgram.h
@@ -4,13 +4,18 @@
 #include "../../runtime/RuntimeShaderArtifact.h"

 #include <string>
+#include <vector>

 struct RuntimePreparedShaderProgram
 {
 	std::string layerId;
 	std::string shaderId;
+	std::string passId;
 	std::string sourceFingerprint;
 	RuntimeShaderArtifact artifact;
+	RuntimeShaderPassArtifact passArtifact;
+	std::vector<std::string> inputNames;
+	std::string outputName;
 	GLuint program = 0;
 	GLuint vertexShader = 0;
 	GLuint fragmentShader = 0;
--- a/apps/RenderCadenceCompositor/render/runtime/RuntimeShaderRenderer.cpp
+++ b/apps/RenderCadenceCompositor/render/runtime/RuntimeShaderRenderer.cpp
@@ -99,21 +99,41 @@ bool RuntimeShaderRenderer::BuildPreparedProgram(
 	const std::string& sourceFingerprint,
 	const RuntimeShaderArtifact& artifact,
 	RuntimePreparedShaderProgram& preparedProgram)
+{
+	RuntimeShaderPassArtifact passArtifact;
+	passArtifact.passId = "main";
+	passArtifact.fragmentShaderSource = artifact.fragmentShaderSource;
+	passArtifact.outputName = "layerOutput";
+	if (!artifact.passes.empty())
+		passArtifact = artifact.passes.front();
+	return BuildPreparedPassProgram(layerId, sourceFingerprint, artifact, passArtifact, preparedProgram);
+}
+
+bool RuntimeShaderRenderer::BuildPreparedPassProgram(
+	const std::string& layerId,
+	const std::string& sourceFingerprint,
+	const RuntimeShaderArtifact& artifact,
+	const RuntimeShaderPassArtifact& passArtifact,
+	RuntimePreparedShaderProgram& preparedProgram)
 {
 	preparedProgram = RuntimePreparedShaderProgram();
 	preparedProgram.layerId = layerId;
 	preparedProgram.shaderId = artifact.shaderId;
+	preparedProgram.passId = passArtifact.passId;
 	preparedProgram.sourceFingerprint = sourceFingerprint;
 	preparedProgram.artifact = artifact;
+	preparedProgram.passArtifact = passArtifact;
+	preparedProgram.inputNames = passArtifact.inputNames;
+	preparedProgram.outputName = passArtifact.outputName.empty() ? passArtifact.passId : passArtifact.outputName;

-	if (artifact.fragmentShaderSource.empty())
+	if (passArtifact.fragmentShaderSource.empty())
 	{
 		preparedProgram.error = "Cannot prepare an empty fragment shader.";
 		return false;
 	}

 	if (!BuildProgram(
-		artifact.fragmentShaderSource,
+		passArtifact.fragmentShaderSource,
 		preparedProgram.program,
 		preparedProgram.vertexShader,
 		preparedProgram.fragmentShader,
--- a/apps/RenderCadenceCompositor/render/runtime/RuntimeShaderRenderer.h
+++ b/apps/RenderCadenceCompositor/render/runtime/RuntimeShaderRenderer.h
@@ -28,6 +28,12 @@ public:
 		const std::string& sourceFingerprint,
 		const RuntimeShaderArtifact& artifact,
 		RuntimePreparedShaderProgram& preparedProgram);
+	static bool BuildPreparedPassProgram(
+		const std::string& layerId,
+		const std::string& sourceFingerprint,
+		const RuntimeShaderArtifact& artifact,
+		const RuntimeShaderPassArtifact& passArtifact,
+		RuntimePreparedShaderProgram& preparedProgram);

 private:
 	bool EnsureStaticGlResources(std::string& error);