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Improve DDGI cascade selection by using biased world position

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This commit is contained in:
Wojtek Figat
2024-06-18 10:52:28 +02:00
parent e0028d5f94
commit 611961cefe
1 changed files with 4 additions and 7 deletions
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11
Source/Shaders/GI/DDGI.hlsl
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@@ -139,14 +139,16 @@ float3 SampleDDGIIrradiance(DDGIData data, Texture2D<snorm float4> probesData, T
// Select the highest cascade that contains the sample location
uint cascadeIndex = 0;
float probesSpacing = 0;
float3 probesOrigin = (float3)0, probesExtent = (float3)0;
float3 probesOrigin = (float3)0, probesExtent = (float3)0, biasedWorldPosition = (float3)0;
float3 viewDir = normalize(data.ViewPos - worldPosition);
for (; cascadeIndex < data.CascadesCount; cascadeIndex++)
{
probesSpacing = data.ProbesOriginAndSpacing[cascadeIndex].w;
probesOrigin = data.ProbesScrollOffsets[cascadeIndex].xyz * probesSpacing + data.ProbesOriginAndSpacing[cascadeIndex].xyz;
probesExtent = (data.ProbesCounts - 1) * (probesSpacing * 0.5f);
biasedWorldPosition = worldPosition + (worldNormal * 0.2f + viewDir * 0.8f) * (0.75f * probesSpacing * bias);
float fadeDistance = probesSpacing * 0.5f;
float cascadeWeight = saturate(Min3(probesExtent - abs(worldPosition - probesOrigin)) / fadeDistance);
float cascadeWeight = saturate(Min3(probesExtent - abs(biasedWorldPosition - probesOrigin)) / fadeDistance);
if (cascadeWeight > dither) // Use dither to make transition smoother
break;
}
@@ -155,11 +157,6 @@ float3 SampleDDGIIrradiance(DDGIData data, Texture2D<snorm float4> probesData, T
uint3 probeCoordsEnd = data.ProbesCounts - uint3(1, 1, 1);
uint3 baseProbeCoords = clamp(uint3((worldPosition - probesOrigin + probesExtent) / probesSpacing), uint3(0, 0, 0), probeCoordsEnd);
// Bias the world-space position to reduce artifacts
float3 viewDir = normalize(data.ViewPos - worldPosition);
float3 surfaceBias = (worldNormal * 0.2f + viewDir * 0.8f) * (0.75f * probesSpacing * bias);
float3 biasedWorldPosition = worldPosition + surfaceBias;
// Get the grid coordinates of the probe nearest the biased world position
float3 baseProbeWorldPosition = GetDDGIProbeWorldPosition(data, cascadeIndex, baseProbeCoords);
float3 biasAlpha = saturate((biasedWorldPosition - baseProbeWorldPosition) / probesSpacing);