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