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74 行
2.8 KiB
74 行
2.8 KiB
#include "CoreRP/ShaderLibrary/Common.hlsl"
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// ------------------------------------------------
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// Algorithm
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// ------------------------------------------------
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// Downsample a depth texture by taking min value of sampled pixels
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// ------------------------------------------------
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// Variants
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// ------------------------------------------------
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#pragma kernel KDepthDownSample8 KERNEL_SIZE=8 KERNEL_NAME=KDepthDownSample8
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#pragma kernel KDepthDownSample1 KERNEL_SIZE=1 KERNEL_NAME=KDepthDownSample1
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#pragma only_renderers d3d11 ps4 xboxone vulkan metal switch
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// ------------------------------------------------
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// Texture buffers
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// ------------------------------------------------
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Texture2D<float2> _Source;
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RW_TEXTURE2D(float2, _Result);
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SamplerState sampler_PointClamp; //TODO: could we use min-sampler instead of using ALU?
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// ------------------------------------------------
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// Constant buffers
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// ------------------------------------------------
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CBUFFER_START(cb)
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float4 _SrcSize;
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int2 _RectOffset; // Offset in source texture
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CBUFFER_END
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// ------------------------------------------------
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// Kernel
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// ------------------------------------------------
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#if UNITY_REVERSED_Z
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# define MIN_DEPTH(l, r) max(l, r)
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# define MAX_DEPTH(l, r) min(l, r)
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#else
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# define MIN_DEPTH(l, r) min(l, r)
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# define MAX_DEPTH(l, r) max(l, r)
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#endif
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[numthreads(KERNEL_SIZE, KERNEL_SIZE, 1)]
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void KERNEL_NAME(uint2 groupId : SV_GroupID, uint2 groupThreadId : SV_GroupThreadID, uint2 dispatchThreadId : SV_DispatchThreadID)
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{
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// Upper-left pixel coordinate of quad that this thread will read
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uint2 srcPixelUL = _RectOffset + (dispatchThreadId << 1);
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// Offset by 0.5 so sampling get the proper pixels
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float2 offset = float2(srcPixelUL) + 0.5;
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#if defined(PLATFORM_SUPPORT_GATHER)
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float4 depths = GATHER_RED_TEXTURE2D(_Source, sampler_PointClamp, offset * _SrcSize.zw, 0.0).wzxy;
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#else
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float p00 = SAMPLE_TEXTURE2D_LOD(_Source, sampler_PointClamp, (offset) * _SrcSize.zw, 0.0).x;
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float p10 = SAMPLE_TEXTURE2D_LOD(_Source, sampler_PointClamp, (offset + float2(1.0, 0.0)) * _SrcSize.zw, 0.0).x;
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float p01 = SAMPLE_TEXTURE2D_LOD(_Source, sampler_PointClamp, (offset + float2(0.0, 1.0)) * _SrcSize.zw, 0.0).x;
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float p11 = SAMPLE_TEXTURE2D_LOD(_Source, sampler_PointClamp, (offset + float2(1.0, 1.0)) * _SrcSize.zw, 0.0).x;
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float4 depths = float4(p00, p10, p01, p11);
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#endif
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// Select the nearest sample
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float minDepth = MIN_DEPTH(MIN_DEPTH(depths.x, depths.y), MIN_DEPTH(depths.z, depths.w));
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float maxDepth = MAX_DEPTH(MAX_DEPTH(depths.x, depths.y), MAX_DEPTH(depths.z, depths.w));
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// Write to the final target
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uint2 dstPixel = (_RectOffset >> 1) + dispatchThreadId;
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_Result[dstPixel] = float2(minDepth, maxDepth);
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}
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#undef MIN_DEPTH
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#undef MAX_DEPTH
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