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Fix Global SDF inside geometry to be negative

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This commit is contained in:
Wojciech Figat
2022-08-12 16:00:27 +02:00
parent 9b816a321c
commit 1e8e5c0f7c
1 changed files with 17 additions and 2 deletions
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19
Source/Shaders/GlobalSignDistanceField.shader
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@@ -73,18 +73,26 @@ Texture3D<float> ObjectsTextures[GLOBAL_SDF_RASTERIZE_MODEL_MAX_COUNT] : registe
float DistanceToModelSDF(float minDistance, ObjectRasterizeData modelData, Texture3D<float> modelSDFTex, float3 worldPos)
{
// Object scaling is the length of the rows
float3 volumeToWorldScale = float3(length(modelData.VolumeToWorld[0]), length(modelData.VolumeToWorld[1]), length(modelData.VolumeToWorld[2]));
float volumeScale = min(volumeToWorldScale.x, min(volumeToWorldScale.y, volumeToWorldScale.z));
// Compute SDF volume UVs and distance in world-space to the volume bounds
float3 volumePos = mul(float4(worldPos, 1), modelData.WorldToVolume).xyz;
float3 volumeUV = volumePos * modelData.VolumeToUVWMul + modelData.VolumeToUVWAdd;
float3 volumePosClamped = clamp(volumePos, -modelData.VolumeLocalBoundsExtent, modelData.VolumeLocalBoundsExtent);
float3 worldPosClamped = mul(float4(volumePosClamped, 1), modelData.VolumeToWorld).xyz;
float distanceToVolume = distance(worldPos, worldPosClamped);
if (distanceToVolume < 0.01f)
distanceToVolume = length((volumePos - volumePosClamped) * volumeToWorldScale);
distanceToVolume = max(distanceToVolume, 0);
// Skip sampling SDF if there is already a better result
BRANCH if (minDistance <= distanceToVolume) return distanceToVolume;
// Sample SDF
float volumeDistance = modelSDFTex.SampleLevel(SamplerLinearClamp, volumeUV, modelData.MipOffset).x * modelData.DecodeMul + modelData.DecodeAdd;
volumeDistance *= volumeScale; // Apply uniform instance scale (non-uniform is not supported)
// Combine distance to the volume with distance to the surface inside the model
float result = CombineDistanceToSDF(volumeDistance, distanceToVolume);
@@ -116,7 +124,7 @@ void CS_RasterizeModel(uint3 DispatchThreadId : SV_DispatchThreadID)
float objectDistance = DistanceToModelSDF(minDistance, objectData, ObjectsTextures[i], voxelWorldPos);
minDistance = min(minDistance, objectDistance);
}
GlobalSDFTex[voxelCoord] = saturate(minDistance / MaxDistance);
GlobalSDFTex[voxelCoord] = clamp(minDistance / MaxDistance, -1, 1);
}
#endif
@@ -161,7 +169,7 @@ void CS_RasterizeHeightfield(uint3 DispatchThreadId : SV_DispatchThreadID)
objectDistance = thickness - objectDistance;
minDistance = min(minDistance, objectDistance);
}
GlobalSDFTex[voxelCoord] = saturate(minDistance / MaxDistance);
GlobalSDFTex[voxelCoord] = clamp(minDistance / MaxDistance, -1, 1);
}
#endif
@@ -249,6 +257,13 @@ float4 PS_Debug(Quad_VS2PS input) : SV_Target
return float4(0, 1 - distance01, 0, 1);
#endif
#if 1
// Debug negative SDF (inside geometry)
float viewSDF = SampleGlobalSDF(GlobalSDF, GlobalSDFTex, GlobalSDFMip, ViewWorldPos);
if (viewSDF < 0)
return float4(float3(0.7, 0.4, 0.1) * saturate(viewSDF * -0.005f), 1);
#endif
// Shot a ray from camera into the Global SDF
GlobalSDFTrace trace;
float3 viewRay = lerp(lerp(ViewFrustumWorldRays[3], ViewFrustumWorldRays[0], input.TexCoord.x), lerp(ViewFrustumWorldRays[2], ViewFrustumWorldRays[1], input.TexCoord.x), 1 - input.TexCoord.y).xyz;