GoaLitiuM/FlaxEngine
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

Add improved terrain rasterization into Global SDF

Browse Source 
#754
This commit is contained in:
Wojtek Figat
2024-06-08 13:14:20 +02:00
parent bc01e6369e
commit 66f9374477
2 changed files with 87 additions and 17 deletions
Download Patch File Download Diff File Expand all files Collapse all files

52
Source/Shaders/GlobalSignDistanceField.shader
View File

@@ -3,6 +3,7 @@
#include "./Flax/Common.hlsl"
#include "./Flax/Math.hlsl"
#include "./Flax/GlobalSignDistanceField.hlsl"
#include "./Flax/TerrainCommon.hlsl"
#define GLOBAL_SDF_RASTERIZE_MODEL_MAX_COUNT 28
#define GLOBAL_SDF_RASTERIZE_HEIGHTFIELD_MAX_COUNT 2
@@ -151,6 +152,9 @@ META_CS(true, FEATURE_LEVEL_SM5)
[numthreads(GLOBAL_SDF_RASTERIZE_GROUP_SIZE, GLOBAL_SDF_RASTERIZE_GROUP_SIZE, GLOBAL_SDF_RASTERIZE_GROUP_SIZE)]
void CS_RasterizeHeightfield(uint3 DispatchThreadId : SV_DispatchThreadID)
{
#if defined(PLATFORM_PS4) || defined(PLATFORM_PS5)
// TODO: fix shader compilation error
#else
uint3 voxelCoord = ChunkCoord + DispatchThreadId;
float3 voxelWorldPos = voxelCoord * CascadeCoordToPosMul + CascadeCoordToPosAdd;
voxelCoord.x += CascadeIndex * CascadeResolution;
@@ -161,33 +165,47 @@ void CS_RasterizeHeightfield(uint3 DispatchThreadId : SV_DispatchThreadID)
ObjectRasterizeData objectData = ObjectsBuffer[Objects[i / 4][i % 4]];
// Convert voxel world-space position into heightfield local-space position and get heightfield UV
float3 volumePos = mul(float4(voxelWorldPos, 1), ToMatrix4x4(objectData.WorldToVolume)).xyz;
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 the heightfield
#if defined(PLATFORM_PS4) || defined(PLATFORM_PS5)
float4 heightmapValue = 0; // TODO: fix shader compilation error
#else
float4 heightmapValue = ObjectsTextures[i].SampleLevel(SamplerLinearClamp, heightfieldUV, objectData.MipOffset);
#endif
bool isHole = (heightmapValue.b + heightmapValue.a) >= 1.9f;
if (isHole || any(heightfieldUV < 0.0f) || any(heightfieldUV > 1.0f))
continue;
float height = (float)((int)(heightmapValue.x * 255.0) + ((int)(heightmapValue.y * 255) << 8)) / 65535.0;
float2 positionXZ = volumePos.xz;
float3 position = float3(positionXZ.x, height, positionXZ.y);
float4x4 volumeToWorld = ToMatrix4x4(objectData.VolumeToWorld);
float3 heightfieldPosition = mul(float4(position, 1), volumeToWorld).xyz;
float3 heightfieldNormal = normalize(float3(volumeToWorld[0].y, volumeToWorld[1].y, volumeToWorld[2].y));
// Sample heightfield around the voxel location (heightmap uses point sampler)
Texture2D<float4> heightmap = ObjectsTextures[i];
float4 localToUV = float4(objectData.VolumeToUVWMul.xz, objectData.VolumeToUVWAdd.xz);
float3 n00, n10, n01, n11;
bool h00, h10, h01, h11;
float offset = CascadeVoxelSize * 2;
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);
float3 p11 = SampleHeightmap(heightmap, volumePos + float3(0, 0, +offset), localToUV, n11, h11, objectData.MipOffset);
// Calculate average sample (linear interpolation)
float3 heightfieldPosition = (p00 + p10 + p01 + p11) * 0.25f;
float3 heightfieldNormal = (n00 + n10 + n01 + n11) * 0.25f;
heightfieldNormal = normalize(heightfieldNormal);
bool isHole = h00 || h10 || h01 || h11;
// Skip holes and pixels outside the heightfield
if (isHole)
continue;
// Transform to world-space
float4x4 localToWorld = ToMatrix4x4(objectData.VolumeToWorld);
heightfieldPosition = mul(float4(heightfieldPosition, 1), localToWorld).xyz;
// TODO: rotate normal vector
//heightfieldNormal = normalize(float3(localToWorld[0].y, localToWorld[1].y, localToWorld[2].y));
//heightfieldNormal = float3(0, 1, 0);
// Calculate distance from voxel center to the heightfield
float objectDistance = dot(heightfieldNormal, voxelWorldPos - heightfieldPosition);
if (objectDistance < thickness)
if (objectDistance < thickness * 0.5f)
objectDistance = thickness - objectDistance;
minDistance = CombineSDF(minDistance, objectDistance);
}
GlobalSDFTex[voxelCoord] = clamp(minDistance / MaxDistance, -1, 1);
#endif
}
#endif

52
Source/Shaders/TerrainCommon.hlsl Normal file
View File

@@ -0,0 +1,52 @@
// Copyright (c) 2012-2024 Wojciech Figat. All rights reserved.
#ifndef __TERRAIN_COMMON__
#define __TERRAIN_COMMON__
#include "./Flax/Common.hlsl"
float SampleHeightmap(Texture2D<float4> heightmap, float2 uv, float mipOffset = 0.0f)
{
// Sample heightmap
float4 value = heightmap.SampleLevel(SamplerPointClamp, uv, mipOffset);
// Decode heightmap
float height = (float)((int)(value.x * 255.0) + ((int)(value.y * 255) << 8)) / 65535.0;
return height;
}
float SampleHeightmap(Texture2D<float4> heightmap, float2 uv, out float3 normal, out bool isHole, float mipOffset = 0.0f)
{
// Sample heightmap
float4 value = heightmap.SampleLevel(SamplerPointClamp, uv, mipOffset);
// Decode heightmap
float height = (float)((int)(value.x * 255.0) + ((int)(value.y * 255) << 8)) / 65535.0;
float2 normalTemp = float2(value.b, value.a) * 2.0f - 1.0f;
normal = float3(normalTemp.x, sqrt(1.0 - saturate(dot(normalTemp, normalTemp))), normalTemp.y);
isHole = (value.b + value.a) >= 1.9f;
normal = normalize(normal);
return height;
}
float3 SampleHeightmap(Texture2D<float4> heightmap, float3 localPosition, float4 localToUV, out float3 normal, out bool isHole, float mipOffset = 0.0f)
{
// Sample heightmap
float2 uv = localPosition.xz * localToUV.xy + localToUV.zw;
float4 value = heightmap.SampleLevel(SamplerPointClamp, uv, mipOffset);
// Decode heightmap
isHole = (value.b + value.a) >= 1.9f;
float height = (float)((int)(value.x * 255.0) + ((int)(value.y * 255) << 8)) / 65535.0;
float3 position = float3(localPosition.x, height, localPosition.z);
float2 normalTemp = float2(value.b, value.a) * 2.0f - 1.0f;
normal = float3(normalTemp.x, sqrt(1.0 - saturate(dot(normalTemp, normalTemp))), normalTemp.y);
normal = normalize(normal);
// UVs outside the heightmap are empty
isHole = isHole || any(uv < 0.0f) || any(uv > 1.0f);
return position;
}
#endif