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Improve abdbd1ee64 to better handle cascade transitions

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This commit is contained in:
Wojtek Figat
2024-06-05 13:43:34 +02:00
parent 0620310f4f
commit c26649a0a8
1 changed files with 60 additions and 58 deletions
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118
Source/Shaders/GlobalSignDistanceField.hlsl
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@@ -215,85 +215,87 @@ GlobalSDFHit RayTraceGlobalSDF(const GlobalSDFData data, Texture3D<float> tex, T
hit.HitTime = -1.0f; hit.HitTime = -1.0f;
float chunkSizeDistance = (float)GLOBAL_SDF_RASTERIZE_CHUNK_SIZE / data.Resolution; // Size of the chunk in SDF distance (0-1) float chunkSizeDistance = (float)GLOBAL_SDF_RASTERIZE_CHUNK_SIZE / data.Resolution; // Size of the chunk in SDF distance (0-1)
float chunkMarginDistance = (float)GLOBAL_SDF_RASTERIZE_CHUNK_MARGIN / data.Resolution; // Size of the chunk margin in SDF distance (0-1) float chunkMarginDistance = (float)GLOBAL_SDF_RASTERIZE_CHUNK_MARGIN / data.Resolution; // Size of the chunk margin in SDF distance (0-1)
float nextIntersectionStart = 0.0f; float nextIntersectionStart = trace.MinDistance;
float traceMaxDistance = min(trace.MaxDistance, data.CascadePosDistance[3].w * 2); float traceMaxDistance = min(trace.MaxDistance, data.CascadePosDistance[3].w * 2);
float3 traceEndPosition = trace.WorldPosition + trace.WorldDirection * traceMaxDistance; float3 traceEndPosition = trace.WorldPosition + trace.WorldDirection * traceMaxDistance;
LOOP
for (uint cascade = 0; cascade < data.CascadesCount && hit.HitTime < 0.0f; cascade++) for (uint cascade = 0; cascade < data.CascadesCount && hit.HitTime < 0.0f; cascade++)
{ {
float4 cascadePosDistance = data.CascadePosDistance[cascade]; float4 cascadePosDistance = data.CascadePosDistance[cascade];
float voxelSize = data.CascadeVoxelSize[cascade]; float voxelSize = data.CascadeVoxelSize[cascade];
float voxelExtent = voxelSize * 0.5f; float voxelExtent = voxelSize * 0.5f;
float3 worldPosition = trace.WorldPosition + trace.WorldDirection * max(voxelSize * cascadeTraceStartBias, trace.MinDistance); float3 worldPosition = trace.WorldPosition;
// Skip until cascade that contains the start location
if (any(abs(worldPosition - cascadePosDistance.xyz) > cascadePosDistance.w))
continue;
// Hit the cascade bounds to find the intersection points // Hit the cascade bounds to find the intersection points
float traceStartBias = voxelSize * cascadeTraceStartBias;
float2 intersections = LineHitBox(worldPosition, traceEndPosition, cascadePosDistance.xyz - cascadePosDistance.www, cascadePosDistance.xyz + cascadePosDistance.www); float2 intersections = LineHitBox(worldPosition, traceEndPosition, cascadePosDistance.xyz - cascadePosDistance.www, cascadePosDistance.xyz + cascadePosDistance.www);
intersections.xy *= traceMaxDistance; intersections.xy *= traceMaxDistance;
intersections.x = max(intersections.x, traceStartBias);
intersections.x = max(intersections.x, nextIntersectionStart); intersections.x = max(intersections.x, nextIntersectionStart);
if (intersections.x >= intersections.y) if (intersections.x < intersections.y)
{ {
// Skip the current cascade if the ray starts outside it // Skip the current cascade tracing on the next cascade
continue; nextIntersectionStart = max(nextIntersectionStart, intersections.y - voxelSize);
}
// Skip the current cascade tracing on the next cascade (if we're tracing from inside SDF volume) // Walk over the cascade SDF
if (intersections.x <= 0.0f) uint step = 0;
nextIntersectionStart = intersections.y; float stepTime = intersections.x;
LOOP
// Walk over the cascade SDF for (; step < 250 && stepTime < intersections.y && hit.HitTime < 0.0f; step++)
uint step = 0;
float stepTime = intersections.x;
LOOP
for (; step < 250 && stepTime < intersections.y; step++)
{
float3 stepPosition = worldPosition + trace.WorldDirection * stepTime;
// Sample SDF
float cascadeMaxDistance;
float3 cascadeUV, textureUV;
GetGlobalSDFCascadeUV(data, cascade, stepPosition, cascadeMaxDistance, cascadeUV, textureUV);
float stepDistance = mip.SampleLevel(SamplerLinearClamp, textureUV, 0);
if (stepDistance < chunkSizeDistance)
{ {
float stepDistanceTex = tex.SampleLevel(SamplerLinearClamp, textureUV, 0); float3 stepPosition = worldPosition + trace.WorldDirection * stepTime;
if (stepDistanceTex < chunkMarginDistance * 2)
// Sample SDF
float cascadeMaxDistance;
float3 cascadeUV, textureUV;
GetGlobalSDFCascadeUV(data, cascade, stepPosition, cascadeMaxDistance, cascadeUV, textureUV);
float stepDistance = mip.SampleLevel(SamplerLinearClamp, textureUV, 0);
if (stepDistance < chunkSizeDistance)
{ {
stepDistance = stepDistanceTex; float stepDistanceTex = tex.SampleLevel(SamplerLinearClamp, textureUV, 0);
if (stepDistanceTex < chunkMarginDistance * 2)
{
stepDistance = stepDistanceTex;
}
} }
} else
else
{
// Assume no SDF nearby so perform a jump
stepDistance = chunkSizeDistance;
}
stepDistance *= cascadeMaxDistance;
// Detect surface hit
float minSurfaceThickness = voxelExtent * saturate(stepTime / voxelSize);
if (stepDistance < minSurfaceThickness)
{
// Surface hit
hit.HitTime = max(stepTime + stepDistance - minSurfaceThickness, 0.0f);
hit.HitCascade = cascade;
hit.HitSDF = stepDistance;
if (trace.NeedsHitNormal)
{ {
// Calculate hit normal from SDF gradient // Assume no SDF nearby so perform a jump
float texelOffset = 1.0f / data.Resolution; stepDistance = chunkSizeDistance;
float xp = tex.SampleLevel(SamplerLinearClamp, float3(textureUV.x + texelOffset, textureUV.y, textureUV.z), 0).x;
float xn = tex.SampleLevel(SamplerLinearClamp, float3(textureUV.x - texelOffset, textureUV.y, textureUV.z), 0).x;
float yp = tex.SampleLevel(SamplerLinearClamp, float3(textureUV.x, textureUV.y + texelOffset, textureUV.z), 0).x;
float yn = tex.SampleLevel(SamplerLinearClamp, float3(textureUV.x, textureUV.y - texelOffset, textureUV.z), 0).x;
float zp = tex.SampleLevel(SamplerLinearClamp, float3(textureUV.x, textureUV.y, textureUV.z + texelOffset), 0).x;
float zn = tex.SampleLevel(SamplerLinearClamp, float3(textureUV.x, textureUV.y, textureUV.z - texelOffset), 0).x;
hit.HitNormal = normalize(float3(xp - xn, yp - yn, zp - zn));
} }
break; stepDistance *= cascadeMaxDistance;
}
// Move forward // Detect surface hit
stepTime += max(stepDistance * trace.StepScale, voxelSize); float minSurfaceThickness = voxelExtent * saturate(stepTime / voxelSize);
if (stepDistance < minSurfaceThickness)
{
// Surface hit
hit.HitTime = max(stepTime + stepDistance - minSurfaceThickness, 0.0f);
hit.HitCascade = cascade;
hit.HitSDF = stepDistance;
if (trace.NeedsHitNormal)
{
// Calculate hit normal from SDF gradient
float texelOffset = 1.0f / data.Resolution;
float xp = tex.SampleLevel(SamplerLinearClamp, float3(textureUV.x + texelOffset, textureUV.y, textureUV.z), 0).x;
float xn = tex.SampleLevel(SamplerLinearClamp, float3(textureUV.x - texelOffset, textureUV.y, textureUV.z), 0).x;
float yp = tex.SampleLevel(SamplerLinearClamp, float3(textureUV.x, textureUV.y + texelOffset, textureUV.z), 0).x;
float yn = tex.SampleLevel(SamplerLinearClamp, float3(textureUV.x, textureUV.y - texelOffset, textureUV.z), 0).x;
float zp = tex.SampleLevel(SamplerLinearClamp, float3(textureUV.x, textureUV.y, textureUV.z + texelOffset), 0).x;
float zn = tex.SampleLevel(SamplerLinearClamp, float3(textureUV.x, textureUV.y, textureUV.z - texelOffset), 0).x;
hit.HitNormal = normalize(float3(xp - xn, yp - yn, zp - zn));
}
}
// Move forward
stepTime += max(stepDistance * trace.StepScale, voxelSize);
}
hit.StepsCount += step;
} }
hit.StepsCount += step;
} }
return hit; return hit;
} }