78 lines
2.0 KiB
GLSL
78 lines
2.0 KiB
GLSL
// Copyright (c) 2012-2023 Wojciech Figat. All rights reserved.
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#include "./Flax/Common.hlsl"
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// Those defines must match the C++
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#define THREADGROUP_SIZE_X 16
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#define THREADGROUP_SIZE_Y 16
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#define HISTOGRAM_SIZE 64
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META_CB_BEGIN(0, Data)
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uint2 InputSize;
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float HistogramMul;
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float HistogramAdd;
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META_CB_END
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#ifdef _CS_ClearHistogram
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RWStructuredBuffer<uint> HistogramBuffer : register(u0);
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// Clears the histogram
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META_CS(true, FEATURE_LEVEL_SM5)
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[numthreads(THREADGROUP_SIZE_X, 1, 1)]
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void CS_ClearHistogram(uint dispatchThreadId : SV_DispatchThreadID)
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{
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if (dispatchThreadId < HISTOGRAM_SIZE)
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HistogramBuffer[dispatchThreadId] = 0u;
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}
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#endif
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#ifdef _CS_GenerateHistogram
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Texture2D<float4> Input : register(t0);
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RWStructuredBuffer<uint> HistogramBuffer : register(u0);
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float ComputeHistogramPositionFromLuminance(float luminance)
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{
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return log2(luminance) * HistogramMul + HistogramAdd;
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}
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groupshared uint SharedHistogram[HISTOGRAM_SIZE];
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// Generates the histogram
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META_CS(true, FEATURE_LEVEL_SM5)
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[numthreads(THREADGROUP_SIZE_X, THREADGROUP_SIZE_Y, 1)]
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void CS_GenerateHistogram(uint3 groupId : SV_GroupID, uint3 dispatchThreadId : SV_DispatchThreadID, uint3 groupThreadId : SV_GroupThreadID, uint groupIndex : SV_GroupIndex)
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{
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const uint localThreadId = groupThreadId.y * THREADGROUP_SIZE_X + groupThreadId.x;
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// Clear the histogram
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if (localThreadId < HISTOGRAM_SIZE)
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SharedHistogram[localThreadId] = 0u;
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GroupMemoryBarrierWithGroupSync();
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// Gather local group histogram
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if (dispatchThreadId.x < InputSize.x && dispatchThreadId.y < InputSize.y)
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{
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uint weight = 1u;
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float3 color = Input[dispatchThreadId.xy].xyz;
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float luminance = Luminance(color);
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float logLuminance = ComputeHistogramPositionFromLuminance(luminance);
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uint idx = (uint)(saturate(logLuminance) * (HISTOGRAM_SIZE - 1u));
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InterlockedAdd(SharedHistogram[idx], weight);
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}
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GroupMemoryBarrierWithGroupSync();
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// Merge everything
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if (localThreadId < HISTOGRAM_SIZE)
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InterlockedAdd(HistogramBuffer[localThreadId], SharedHistogram[localThreadId]);
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}
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#endif
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