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PathTracer: Simplify Depth AOV logic

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Only need to track Z value across hits, not the hit point or a counter. This reduces the live state by 20 bytes (432 down to 412) and speeds up the path tracer by roughly 2%.

[CL 30244787 by chris kulla in ue5-main branch]
This commit is contained in:
chris kulla
2023-12-11 14:09:56 -05:00
parent bb3cf32aa3
commit cd05291f51
3 changed files with 20 additions and 85 deletions
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Engine/Shaders/Private/PathTracing/Material/PathTracingMaterialSampling.ush
-44
View File
@@ -271,49 +271,6 @@ void AccumulateAlbedo(float3 SigmaS, float3 PathThroughput, float PathRoughness,
#endif // SIMPLIFIED_MATERIAL_SHADER
#define DEBUG_DEPTH_SAMPLING 0
struct FDepthContext
{
float3 TranslatedWorldPos;
uint HitCount;
#if DEBUG_DEPTH_SAMPLING
// visualize the depth status for the ith ray hit.
int DebugHitCount;
#endif
void AddHit(FPathTracingPayload Payload)
{
#if DEBUG_DEPTH_SAMPLING
if (DebugHitCount == 0)
{
return;
}
#endif
// 2. Matching depth output to the rasterizer.
if (Payload.ShouldOutputDepth() && HitCount == 0)
{
TranslatedWorldPos = Payload.TranslatedWorldPos;
HitCount++;
}
#if DEBUG_DEPTH_SAMPLING
DebugHitCount--;
#endif
}
};
FDepthContext InitDepthContext()
{
FDepthContext Context = (FDepthContext)0;
#if DEBUG_DEPTH_SAMPLING
Context.DebugHitCount = View.GeneralPurposeTweak;
#endif
return Context;
}
// returns an average roughness for the whole material (for the path roughness of shadow rays from this material)
float GetAverageRoughness(FPathTracingPayload Payload)
{
@@ -326,7 +283,6 @@ float GetAverageRoughness(FPathTracingPayload Payload)
case SHADINGMODELID_SUBSTRATE:
case SHADINGMODELID_THIN_TRANSLUCENT:
{
AvgRoughness = max(AvgRoughness, Payload.RoughnessData.y);
// Only non-glass slabs contain diffuse
float3 DiffuseColor = Payload.HasRefraction() ? 0.0 : Payload.SubsurfaceColor + Payload.DiffuseColor;
Engine/Shaders/Private/PathTracing/PathTracing.usf
+11 -3
View File
@@ -141,6 +141,13 @@ RAY_TRACING_ENTRY_RAYGEN(PathTracingMainRG)
}
const bool KeepGoing = PathTracingKernel(PathState, Bounce);
const uint2 TextureIndex = ComputeTextureIndex(uint2(LinearPixelIndex % DispatchDim.x,
LinearPixelIndex / DispatchDim.x));
if (Bounce == 0)
{
// Camera ray must write depth right away because we don't want to have to carry DepthZ in the PackedPathState
PathState.WriteDepth(TextureIndex);
}
if (KeepGoing)
{
// NOTE: using wave instructions to reduce contention seems to run slightly slower? (tested on RTX-3080)
@@ -153,8 +160,7 @@ RAY_TRACING_ENTRY_RAYGEN(PathTracingMainRG)
{
// nothing left to do
// Accumulate radiance and update pixel variance
PathState.WritePixel(ComputeTextureIndex(uint2(LinearPixelIndex % DispatchDim.x,
LinearPixelIndex / DispatchDim.x)));
PathState.WritePixel(TextureIndex);
}
}
@@ -193,7 +199,9 @@ RAY_TRACING_ENTRY_RAYGEN(PathTracingMainRG)
}
// Accumulate radiance and update pixel variance
PathState.WritePixel();
int2 TextureIndex = ComputeTextureIndex(DispatchIdx);
PathState.WritePixel(TextureIndex);
PathState.WriteDepth(TextureIndex);
}
#endif
Engine/Shaders/Private/PathTracing/PathTracingCore.ush
+9 -38
View File
@@ -92,8 +92,7 @@ struct FPathState
// 80 bytes total (see FPathTracingPackedPathState)
// Temporary parameters not stored
bool DepthResamplingWeight;
int2 PrimaryRayTextureIndex; // texture index cache to write to the frame buffer for primary ray operation like depth.
float DepthZ; // Camera ray depth
bool HasMadeContributionScatter()
{
@@ -196,24 +195,10 @@ struct FPathState
NormalTexture[TextureIndex].xyz = lerp(OldNormal.xyz,Normal.xyz, Blend);
}
void WritePixel()
void WriteDepth(uint2 TextureIndex)
{
WritePixel(PrimaryRayTextureIndex);
}
void WriteDepth(FDepthContext DepthContext)
{
float OldDepth = Iteration > 0 ? NormalTexture[PrimaryRayTextureIndex].w : 0;
float Depth = 0;
if (DepthContext.HitCount > 0)
{
const float3 ViewZ = View.ViewToTranslatedWorld[2].xyz;
Depth = dot(DepthContext.TranslatedWorldPos, ViewZ);
}
NormalTexture[PrimaryRayTextureIndex].w = lerp(OldDepth, max(OldDepth, ConvertToDeviceZ(Depth)), DepthResamplingWeight);
float OldDepth = Iteration > 0 ? NormalTexture[TextureIndex].w : 0;
NormalTexture[TextureIndex].w = max(OldDepth, ConvertToDeviceZ(DepthZ));
}
};
@@ -413,7 +398,6 @@ FPathTracingPayload TraceTransparentRay(inout FPathState PathState, int Bounce,
float2 RISRandSample = RandomSequence_GenerateSample2D(PathState.RandSequence);
FRISContext HitSample = InitRISContext(RISRandSample.x);
FRISContext VolSample = InitRISContext(RISRandSample.y);
FDepthContext DepthContext = InitDepthContext();
float3 PayloadThroughput = PathState.PathThroughput;
FPathTracingPayload Payload;
@@ -696,9 +680,10 @@ FPathTracingPayload TraceTransparentRay(inout FPathState PathState, int Bounce,
break;
}
if (bIsCameraRay)
if (bIsCameraRay && HitPayload.ShouldOutputDepth() && PathState.DepthZ == 0.0)
{
DepthContext.AddHit(HitPayload);
const float3 ViewZ = View.ViewToTranslatedWorld[2].xyz;
PathState.DepthZ = dot(HitPayload.TranslatedWorldPos, ViewZ);
}
if (!bLastBounce)
@@ -744,11 +729,6 @@ FPathTracingPayload TraceTransparentRay(inout FPathState PathState, int Bounce,
Payload.SetMiss();
}
if (bIsCameraRay)
{
PathState.WriteDepth(DepthContext);
}
return Payload;
}
@@ -1341,7 +1321,7 @@ bool ProcessSubsurfaceRandomWalk(inout FPathTracingPayload Payload, inout float3
return false;
}
FPathState CreatePathState(int2 PixelIndex, int2 PrimaryRayTextureIndex)
FPathState CreatePathState(int2 PixelIndex, int2 TextureIndex)
{
FPathState Output = (FPathState)0;
@@ -1350,7 +1330,7 @@ FPathState CreatePathState(int2 PixelIndex, int2 PrimaryRayTextureIndex)
#if PATH_TRACER_USE_ADAPTIVE_SAMPLING
// initialize progressive sobol sequence based on current index for this pixel
// NOTE: Error diffusion sampler cannot be used in this mode
int SampleIndex = int(VarianceTexture[PrimaryRayTextureIndex].z);
int SampleIndex = int(VarianceTexture[TextureIndex].z);
RandomSequence_Initialize(Output.RandSequence, LaunchIndex.x + LaunchIndex.y * 65536, TemporalSeed - Iteration + SampleIndex);
#else
// Initialize random sequence
@@ -1377,14 +1357,6 @@ FPathState CreatePathState(int2 PixelIndex, int2 PrimaryRayTextureIndex)
float2 ViewportUV = (LaunchIndex + AAJitter) * View.BufferSizeAndInvSize.zw;
Output.Ray = CreatePrimaryRay(ViewportUV);
#if 0
// only record the depth within a square.
Output.DepthResamplingWeight = all(AAJitter >= 0.0) && all(AAJitter <= 1.0) ? 1 : 0;
#else
// record depth for all rays in the filter footprint (TODO: simplify code that uses this weight instead)
Output.DepthResamplingWeight = 1.0;
#endif
}
if (CameraLensRadius.y > 0)
@@ -1414,7 +1386,6 @@ FPathState CreatePathState(int2 PixelIndex, int2 PrimaryRayTextureIndex)
Output.PathRoughness = 0;
Output.SigmaT = float3(StartingExtinctionCoefficient[0], StartingExtinctionCoefficient[1], StartingExtinctionCoefficient[2]);
Output.FirstScatterType = PATHTRACER_SCATTER_CAMERA;
Output.PrimaryRayTextureIndex = PrimaryRayTextureIndex;
return Output;
}