random float

apps/LoopThroughWithOpenGLCompositing/gl/GlobalParamsBuffer.cpp

@@ -20,6 +20,7 @@ bool GlobalParamsBuffer::Update(const RuntimeRenderState& state, unsigned availa
 	AppendStd140Vec2(buffer, static_cast<float>(state.outputWidth), static_cast<float>(state.outputHeight));
 	AppendStd140Float(buffer, static_cast<float>(state.utcTimeSeconds));
 	AppendStd140Float(buffer, static_cast<float>(state.utcOffsetSeconds));
+	AppendStd140Float(buffer, static_cast<float>(state.startupRandom));
 	AppendStd140Float(buffer, static_cast<float>(state.frameCount));
 	AppendStd140Float(buffer, static_cast<float>(state.mixAmount));
 	AppendStd140Float(buffer, static_cast<float>(state.bypass));

apps/LoopThroughWithOpenGLCompositing/runtime/RuntimeHost.cpp

@@ -9,6 +9,7 @@
 #include <algorithm>
 #include <cmath>
 #include <fstream>
+#include <random>
 #include <set>
 #include <sstream>
 
@@ -55,6 +56,13 @@ bool MatchesControlKey(const std::string& candidate, const std::string& key)
 	return candidate == key || SimplifyControlKey(candidate) == SimplifyControlKey(key);
 }
 
+double GenerateStartupRandom()
+{
+	std::random_device randomDevice;
+	std::uniform_real_distribution<double> distribution(0.0, 1.0);
+	return distribution(randomDevice);
+}
+
 bool TryParseLayerIdNumber(const std::string& layerId, uint64_t& number)
 {
 	const std::string prefix = "layer-";
@@ -691,6 +699,7 @@ RuntimeHost::RuntimeHost()
 	mCompletionIntervalMilliseconds(0.0),
 	mSmoothedCompletionIntervalMilliseconds(0.0),
 	mMaxCompletionIntervalMilliseconds(0.0),
+	mStartupRandom(GenerateStartupRandom()),
 	mLateFrameCount(0),
 	mDroppedFrameCount(0),
 	mFlushedFrameCount(0),
@@ -1351,6 +1360,7 @@ void RuntimeHost::RefreshDynamicRenderStateFields(std::vector<RuntimeRenderState
 		state.timeSeconds = timeSeconds;
 		state.utcTimeSeconds = clock.utcTimeSeconds;
 		state.utcOffsetSeconds = clock.utcOffsetSeconds;
+		state.startupRandom = mStartupRandom;
 		state.frameCount = frameCount;
 	}
 }

apps/LoopThroughWithOpenGLCompositing/runtime/RuntimeHost.h

@@ -167,6 +167,7 @@ private:
 	double mCompletionIntervalMilliseconds;
 	double mSmoothedCompletionIntervalMilliseconds;
 	double mMaxCompletionIntervalMilliseconds;
+	double mStartupRandom;
 	uint64_t mLateFrameCount;
 	uint64_t mDroppedFrameCount;
 	uint64_t mFlushedFrameCount;

apps/LoopThroughWithOpenGLCompositing/shader/ShaderTypes.h

@@ -115,6 +115,7 @@ struct RuntimeRenderState
 	double timeSeconds = 0.0;
 	double utcTimeSeconds = 0.0;
 	double utcOffsetSeconds = 0.0;
+	double startupRandom = 0.0;
 	double frameCount = 0.0;
 	double mixAmount = 1.0;
 	double bypass = 0.0;