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303 行
13 KiB
303 行
13 KiB
//--------------------------------------------------------------------------------------------------
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// Definitions
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//--------------------------------------------------------------------------------------------------
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#pragma kernel VolumeVoxelizationBruteforce VolumeVoxelization=VolumeVoxelizationBruteforce LIGHTLOOP_SINGLE_PASS
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#pragma kernel VolumeVoxelizationClustered VolumeVoxelization=VolumeVoxelizationClustered LIGHTLOOP_TILE_PASS USE_CLUSTERED_LIGHTLIST
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// #pragma enable_d3d11_debug_symbols
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#include "../../ShaderPass/ShaderPass.cs.hlsl"
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#define SHADERPASS SHADERPASS_VOLUME_VOXELIZATION
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#include "../../ShaderConfig.cs.hlsl"
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#if (SHADEROPTIONS_VOLUMETRIC_LIGHTING_PRESET == 1)
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// E.g. for 1080p: (1920/8)x(1080/8)x(64) = 2,073,600 voxels
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#define VBUFFER_TILE_SIZE 8
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#define VBUFFER_SLICE_COUNT 64
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#else
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// E.g. for 1080p: (1920/4)x(1080/4)x(128) = 16,588,800 voxels
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#define VBUFFER_TILE_SIZE 4
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#define VBUFFER_SLICE_COUNT 128
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#endif
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#define GROUP_SIZE_1D 8
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#define SOFT_VOXELIZATION 1 // Hack which attempts to determine the partial coverage of the voxel
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//--------------------------------------------------------------------------------------------------
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// Included headers
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//--------------------------------------------------------------------------------------------------
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#include "CoreRP/ShaderLibrary/Common.hlsl"
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#include "CoreRP/GeometryUtils.cs.hlsl"
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#include "../../ShaderVariables.hlsl"
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#include "VolumetricLighting.cs.hlsl"
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#define UNITY_MATERIAL_VOLUMETRIC // Define before including Lighting.hlsl and Material.hlsl
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#include "../Lighting.hlsl" // Includes Material.hlsl
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#pragma only_renderers d3d11 ps4 xboxone vulkan metal
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//--------------------------------------------------------------------------------------------------
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// Inputs & outputs
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//--------------------------------------------------------------------------------------------------
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StructuredBuffer<OrientedBBox> _VolumeBounds;
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StructuredBuffer<DensityVolumeProperties> _VolumeProperties;
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RW_TEXTURE3D(float4, _VBufferDensity); // RGB = sqrt(scattering), A = sqrt(extinction)
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// TODO: avoid creating another Constant Buffer...
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CBUFFER_START(UnityVolumetricLighting)
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float4x4 _VBufferCoordToViewDirWS; // Actually just 3x3, but Unity can only set 4x4
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float4 _VBufferSampleOffset; // Not used by this shader
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float _CornetteShanksConstant; // Not used by this shader
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uint _NumVisibleDensityVolumes;
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CBUFFER_END
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//--------------------------------------------------------------------------------------------------
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// Implementation
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//--------------------------------------------------------------------------------------------------
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void FillVolumetricDensityBuffer(PositionInputs posInput, float3 rayOriginWS, float3 rayUnDirWS,
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float3 voxelAxisRight, float3 voxelAxisUp, float3 voxelAxisForward)
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{
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float n = _VBufferDepthDecodingParams.x + _VBufferDepthDecodingParams.z;
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float z0 = n; // Start the computation from the near plane
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float de = rcp(VBUFFER_SLICE_COUNT); // Log-encoded distance between slices
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#ifdef USE_CLUSTERED_LIGHTLIST
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// The voxel can overlap up to 2 light clusters along Z, so we have to iterate over both.
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// TODO: implement Z-binning which makes Z-range queries easy.
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uint volumeStarts[2], volumeCounts[2];
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GetCountAndStartCluster(posInput.tileCoord, GetLightClusterIndex(posInput.tileCoord, z0),
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LIGHTCATEGORY_DENSITY_VOLUME, volumeStarts[0], volumeCounts[0]);
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#endif // USE_CLUSTERED_LIGHTLIST
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#if defined(SHADER_API_METAL)
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[fastopt]
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for (uint slice = 0; slice < VBUFFER_SLICE_COUNT; slice++)
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#else
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uint sliceCountHack = max(VBUFFER_SLICE_COUNT, (uint)_VBufferDepthEncodingParams.w); // Prevent unrolling...
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// TODO: replace 'sliceCountHack' with VBUFFER_SLICE_COUNT when the shader compiler bug is fixed.
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for (uint slice = 0; slice < sliceCountHack; slice++)
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#endif
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{
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uint3 voxelCoord = uint3(posInput.positionSS, slice);
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float e1 = slice * de + de; // (slice + 1) / sliceCount
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#if defined(SHADER_API_METAL)
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// Warning: this compiles, but it's nonsense. Use DecodeLogarithmicDepthGeneralized().
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float z1 = DecodeLogarithmicDepth(e1, _VBufferDepthDecodingParams);
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#else
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float z1 = DecodeLogarithmicDepthGeneralized(e1, _VBufferDepthDecodingParams);
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#endif
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float halfDZ = 0.5 * (z1 - z0);
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float z = z0 + halfDZ;
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float3 voxelCenterWS = rayOriginWS + z * rayUnDirWS; // Works due to the length of of the dir
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// TODO: define a function ComputeGlobalFogCoefficients(float3 voxelCenterWS),
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// which allows procedural definition of extinction and scattering.
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float3 voxelScattering = _GlobalScattering;
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float voxelExtinction = _GlobalExtinction;
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#ifdef USE_CLUSTERED_LIGHTLIST
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GetCountAndStartCluster(posInput.tileCoord, GetLightClusterIndex(posInput.tileCoord, z1),
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LIGHTCATEGORY_DENSITY_VOLUME, volumeStarts[1], volumeCounts[1]);
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// Iterate over all volumes within 2 (not necessarily unique) clusters overlapping the voxel along Z.
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// We need to skip duplicates, but it's not too difficult since volumes are sorted by index.
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uint i = 0, j = 0;
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if (i < volumeCounts[0] || j < volumeCounts[1])
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{
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// At least one of the clusters is non-empty.
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uint volumeIndices[2];
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// Fetch two initial indices from both clusters.
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volumeIndices[0] = FetchIndexWithBoundsCheck(volumeStarts[0], volumeCounts[0], i);
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volumeIndices[1] = FetchIndexWithBoundsCheck(volumeStarts[1], volumeCounts[1], j);
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do
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{
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// Process volumes in order.
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uint volumeIndex = min(volumeIndices[0], volumeIndices[1]);
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#else // USE_CLUSTERED_LIGHTLIST
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{
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for (uint volumeIndex = 0; volumeIndex < _NumVisibleDensityVolumes; volumeIndex++)
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{
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#endif // USE_CLUSTERED_LIGHTLIST
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OrientedBBox obb = _VolumeBounds[volumeIndex];
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float3x3 obbFrame = float3x3(obb.right, obb.up, cross(obb.up, obb.right));
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float3 obbExtents = float3(obb.extentX, obb.extentY, obb.extentZ);
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// Express the voxel center in the local coordinate system of the box.
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float3 voxelCenterBS = mul(voxelCenterWS - obb.center, transpose(obbFrame));
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float3 voxelCenterUV = voxelCenterBS / obbExtents;
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#if SOFT_VOXELIZATION
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// We need to determine which is the face closest to 'voxelCenterBS'.
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float minFaceDist = abs(obbExtents.x - abs(voxelCenterBS.x));
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// TODO: use v_cubeid_f32.
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uint axisIndex; float faceDist;
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faceDist = abs(obbExtents.y - abs(voxelCenterBS.y));
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axisIndex = (faceDist < minFaceDist) ? 1 : 0;
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minFaceDist = min(faceDist, minFaceDist);
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faceDist = abs(obbExtents.z - abs(voxelCenterBS.z));
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axisIndex = (faceDist < minFaceDist) ? 2 : axisIndex;
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float3 N = float3(axisIndex == 0 ? 1 : 0, axisIndex == 1 ? 1 : 0, axisIndex == 2 ? 1 : 0);
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// We have determined the normal of the closest face.
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// We now have to construct the diagonal of the voxel with the longest extent along this normal.
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float3 minDiagPointBS, maxDiagPointBS;
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float3 voxelAxisRightBS = mul(voxelAxisRight, transpose(obbFrame));
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float3 voxelAxisUpBS = mul(voxelAxisUp, transpose(obbFrame));
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float3 voxelAxisForwardBS = mul(voxelAxisForward, transpose(obbFrame));
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// Start at the center of the voxel.
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minDiagPointBS = maxDiagPointBS = voxelCenterBS;
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bool normalFwd = dot(voxelAxisForwardBS, N) >= 0;
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float mulForward = normalFwd ? halfDZ : -halfDZ;
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float mulMin = normalFwd ? z0 : z1;
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float mulMax = normalFwd ? z1 : z0;
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minDiagPointBS -= mulForward * voxelAxisForwardBS;
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maxDiagPointBS += mulForward * voxelAxisForwardBS;
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float mulUp = dot(voxelAxisUpBS, N) >= 0 ? 1 : -1;
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minDiagPointBS -= (mulMin * mulUp) * voxelAxisUpBS;
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maxDiagPointBS += (mulMax * mulUp) * voxelAxisUpBS;
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float mulRight = dot(voxelAxisRightBS, N) >= 0 ? 1 : -1;
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minDiagPointBS -= (mulMin * mulRight) * voxelAxisRightBS;
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maxDiagPointBS += (mulMax * mulRight) * voxelAxisRightBS;
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// We want to determine the fractional overlap of the diagonal and the box.
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float3 diagOriginBS = minDiagPointBS;
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float3 diagUnDirBS = maxDiagPointBS - minDiagPointBS;
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float tEntr, tExit;
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IntersectRayAABB(diagOriginBS, diagUnDirBS,
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-obbExtents, obbExtents,
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0, 1,
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tEntr, tExit);
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float overlapFraction = tExit - tEntr;
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#else // SOFT_VOXELIZATION
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bool overlap = abs(voxelCenterUV.x) <= 1 &&
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abs(voxelCenterUV.y) <= 1 &&
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abs(voxelCenterUV.z) <= 1;
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float overlapFraction = overlap ? 1 : 0;
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#endif // SOFT_VOXELIZATION
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if (overlapFraction > 0)
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{
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// There is an overlap. Sample the 3D texture, or load the constant value.
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voxelScattering += overlapFraction * _VolumeProperties[volumeIndex].scattering;
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voxelExtinction += overlapFraction * _VolumeProperties[volumeIndex].extinction;
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}
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#ifndef USE_CLUSTERED_LIGHTLIST
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}
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}
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#else // USE_CLUSTERED_LIGHTLIST
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// Advance to the next volume in one (or both at the same time) clusters.
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if (volumeIndex == volumeIndices[0])
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{
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i++;
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volumeIndices[0] = FetchIndexWithBoundsCheck(volumeStarts[0], volumeCounts[0], i);
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}
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if (volumeIndex == volumeIndices[1])
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{
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j++;
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volumeIndices[1] = FetchIndexWithBoundsCheck(volumeStarts[1], volumeCounts[1], j);
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}
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} while (i < volumeCounts[0] || j < volumeCounts[1]);
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}
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// We don't need to carry over the cluster index, only the start and the count.
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volumeStarts[0] = volumeStarts[1];
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volumeCounts[0] = volumeCounts[1];
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#endif // USE_CLUSTERED_LIGHTLIST
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_VBufferDensity[voxelCoord] = float4(voxelScattering, voxelExtinction);
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z0 = z1;
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}
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}
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[numthreads(GROUP_SIZE_1D, GROUP_SIZE_1D, 1)]
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void VolumeVoxelization(uint2 groupId : SV_GroupID,
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uint2 groupThreadId : SV_GroupThreadID)
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{
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// Perform compile-time checks.
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if (!IsPower2(VBUFFER_TILE_SIZE) || !IsPower2(TILE_SIZE_CLUSTERED)) return;
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uint2 groupCoord = groupThreadId;
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uint2 groupOffset = groupId * GROUP_SIZE_1D;
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uint2 voxelCoord = groupOffset + groupCoord;
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uint2 tileCoord = voxelCoord * VBUFFER_TILE_SIZE / TILE_SIZE_CLUSTERED;
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uint voxelsPerClusterTile = Sq((uint)(TILE_SIZE_CLUSTERED / VBUFFER_TILE_SIZE));
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if (voxelsPerClusterTile >= 64)
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{
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// TODO: this is a compile-time test, make sure the compiler actually scalarizes.
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tileCoord = groupOffset * VBUFFER_TILE_SIZE / TILE_SIZE_CLUSTERED;
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}
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UNITY_BRANCH
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if (voxelCoord.x >= (uint)_VBufferResolution.x ||
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voxelCoord.y >= (uint)_VBufferResolution.y)
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{
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return;
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}
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// Reminder: our voxel is a skewed pyramid frustum with square front and back faces.
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// Compute 3x orthogonal directions.
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float2 centerCoord = voxelCoord + float2( 0.5, 0.5);
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float2 leftCoord = voxelCoord + float2(-0.5, 0.5);
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float2 upCoord = voxelCoord + float2( 0.5, -0.5);
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// TODO: avoid 2x matrix multiplications by precomputing the world-space offset on the vs_Z=1 plane.
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// Compute 3x ray directions s.t. its ViewSpace(rayDirWS).z = 1.
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float3 centerDirWS = mul(-float3(centerCoord, 1), (float3x3)_VBufferCoordToViewDirWS);
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float3 leftDirWS = mul(-float3(leftCoord, 1), (float3x3)_VBufferCoordToViewDirWS);
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float3 upDirWS = mul(-float3(upCoord, 1), (float3x3)_VBufferCoordToViewDirWS);
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// Compute the axes of the voxel. These are not normalized, but rather computed to scale with Z.
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float3 voxelAxisForward = centerDirWS;
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float3 voxelAxisUp = 0.5 * (upDirWS - centerDirWS);
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float3 voxelAxisRight = 0.5 * (centerDirWS - leftDirWS);
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PositionInputs posInput = GetPositionInput(voxelCoord, _VBufferResolution.zw, tileCoord);
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FillVolumetricDensityBuffer(posInput, GetCurrentViewPosition(), centerDirWS,
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voxelAxisRight, voxelAxisUp, voxelAxisForward);
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}
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