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Fix blocky terrain SDF

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#3975
This commit is contained in:
Wojtek Figat
2026-03-11 19:25:18 +01:00
parent 96bbae8e28
commit 22c88eb59d
4 changed files with 18 additions and 11 deletions
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BIN
Content/Shaders/GlobalSignDistanceField.flax LFS
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11
Source/Engine/Terrain/Terrain.cpp
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@@ -549,19 +549,22 @@ bool Terrain::DrawSetup(RenderContext& renderContext)
const DrawPass drawModes = DrawModes & renderContext.View.Pass;
if (drawModes == DrawPass::GlobalSDF)
{
const float chunkSize = TERRAIN_UNITS_PER_VERTEX * (float)_chunkSize;
const float posToUV = 0.25f / chunkSize;
Float4 localToUV(posToUV, posToUV, 0.0f, 0.0f);
const float chunkScale = 0.25f / (TERRAIN_UNITS_PER_VERTEX * (float)_chunkSize); // Patch heightfield is divided into 4x4 chunks
for (const TerrainPatch* patch : _patches)
{
if (!patch->Heightmap)
continue;
GPUTexture* heightfield = patch->Heightmap->GetTexture();
float size = (float)heightfield->Width();
Float4 localToUV;
localToUV.X = localToUV.Y = chunkScale * (size - 1) / size; // Skip the last edge texel
localToUV.Z = localToUV.W = 0.5f / size; // Include half-texel offset
Transform patchTransform;
patchTransform.Translation = patch->_offset + Vector3(0, patch->_yOffset, 0);
patchTransform.Orientation = Quaternion::Identity;
patchTransform.Scale = Float3(1.0f, patch->_yHeight, 1.0f);
patchTransform = _transform.LocalToWorld(patchTransform);
GlobalSignDistanceFieldPass::Instance()->RasterizeHeightfield(this, patch->Heightmap->GetTexture(), patchTransform, patch->_bounds, localToUV);
GlobalSignDistanceFieldPass::Instance()->RasterizeHeightfield(this, heightfield, patchTransform, patch->_bounds, localToUV);
}
return true;
}

10
Source/Shaders/GlobalSignDistanceField.shader
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@@ -170,15 +170,14 @@ void CS_RasterizeHeightfield(uint3 DispatchThreadId : SV_DispatchThreadID)
// Convert voxel world-space position into heightfield local-space position and get heightfield UV
float4x4 worldToLocal = ToMatrix4x4(objectData.WorldToVolume);
float3 volumePos = mul(float4(voxelWorldPos, 1), worldToLocal).xyz;
float3 volumeUV = volumePos * objectData.VolumeToUVWMul + objectData.VolumeToUVWAdd;
float2 heightfieldUV = float2(volumeUV.x, volumeUV.z);
// Sample heightfield around the voxel location (heightmap uses point sampler)
Texture2D<float4> heightmap = ObjectsTextures[i];
float4 localToUV = float4(objectData.VolumeToUVWMul.xz, objectData.VolumeToUVWAdd.xz);
#if 1
float3 n00, n10, n01, n11;
bool h00, h10, h01, h11;
float offset = CascadeVoxelSize * 2;
float offset = CascadeVoxelSize;
float3 p00 = SampleHeightmap(heightmap, volumePos + float3(-offset, 0, 0), localToUV, n00, h00, objectData.MipOffset);
float3 p10 = SampleHeightmap(heightmap, volumePos + float3(+offset, 0, 0), localToUV, n10, h10, objectData.MipOffset);
float3 p01 = SampleHeightmap(heightmap, volumePos + float3(0, 0, -offset), localToUV, n01, h01, objectData.MipOffset);
@@ -189,6 +188,11 @@ void CS_RasterizeHeightfield(uint3 DispatchThreadId : SV_DispatchThreadID)
float3 heightfieldNormal = (n00 + n10 + n01 + n11) * 0.25f;
heightfieldNormal = normalize(heightfieldNormal);
bool isHole = h00 || h10 || h01 || h11;
#else
float3 heightfieldNormal;
bool isHole;
float3 heightfieldPosition = SampleHeightmap(heightmap, volumePos, localToUV, heightfieldNormal, isHole, objectData.MipOffset);
#endif
// Skip holes and pixels outside the heightfield
if (isHole)

4
Source/Shaders/TerrainCommon.hlsl
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@@ -35,11 +35,11 @@ float3 SampleHeightmap(Texture2D<float4> heightmap, float3 localPosition, float4
{
// Sample heightmap
float2 uv = localPosition.xz * localToUV.xy + localToUV.zw;
float4 value = heightmap.SampleLevel(SamplerPointClamp, uv, mipOffset);
float4 value = heightmap.SampleLevel(SamplerLinearClamp, uv, mipOffset);
// Decode heightmap
normal = DecodeHeightmapNormal(value, isHole);
float height = DecodeHeightmapHeight(value);;
float height = DecodeHeightmapHeight(value);
float3 position = float3(localPosition.x, height, localPosition.z);
// UVs outside the heightmap are empty