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Add Global Surface Atlas sampling

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This commit is contained in:
Wojciech Figat
2022-04-08 13:54:31 +02:00
parent fbc1e6c861
commit 7735849b7f
2 changed files with 87 additions and 40 deletions
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121
Source/Shaders/GlobalSurfaceAtlas.hlsl
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@@ -5,11 +5,11 @@
// This must match C++
#define GLOBAL_SURFACE_ATLAS_OBJECT_SIZE (5 + 6 * 5) // Amount of float4s per-object
#define GLOBAL_SURFACE_ATLAS_TILE_NORMAL_THRESHOLD 0.3f // Cut-off value for tiles transitions blending during sampling
#define GLOBAL_SURFACE_ATLAS_TILE_NORMAL_THRESHOLD 0.25f // Cut-off value for tiles transitions blending during sampling
struct GlobalSurfaceTile
{
float4 AtlasRect;
float4 AtlasRectUV;
float4x4 WorldToLocal;
float3 ViewBoundsSize;
bool Enabled;
@@ -61,7 +61,7 @@ GlobalSurfaceTile LoadGlobalSurfaceAtlasTile(Buffer<float4> objects, uint object
float4 vector3 = objects.Load(tileStart + 3);
float4 vector4 = objects.Load(tileStart + 4);
GlobalSurfaceTile tile = (GlobalSurfaceTile)0;
tile.AtlasRect = vector0.xyzw;
tile.AtlasRectUV = vector0.xyzw;
tile.WorldToLocal[0] = float4(vector1.xyz, 0.0f);
tile.WorldToLocal[1] = float4(vector2.xyz, 0.0f);
tile.WorldToLocal[2] = float4(vector3.xyz, 0.0f);
@@ -78,11 +78,64 @@ struct GlobalSurfaceAtlasData
uint ObjectsCount;
};
float3 SampleGlobalSurfaceAtlasTex(Texture2D atlas, float2 atlasUV, float4 bilinearWeights)
{
float4 sampleX = atlas.GatherRed(SamplerLinearClamp, atlasUV);
float4 sampleY = atlas.GatherGreen(SamplerLinearClamp, atlasUV);
float4 sampleZ = atlas.GatherBlue(SamplerLinearClamp, atlasUV);
return float3(dot(sampleX, bilinearWeights), dot(sampleY, bilinearWeights), dot(sampleZ, bilinearWeights));
}
float4 SampleGlobalSurfaceAtlasTile(GlobalSurfaceTile tile, Texture2D depth, Texture2D atlas, float3 worldPosition, float3 worldNormal, float surfaceThreshold)
{
// Tile normal weight based on the sampling angle
float3 tileNormal = normalize(mul(worldNormal, (float3x3)tile.WorldToLocal));
float normalWeight = saturate(dot(float3(0, 0, -1), tileNormal));
normalWeight = (normalWeight - GLOBAL_SURFACE_ATLAS_TILE_NORMAL_THRESHOLD) / (1.0f - GLOBAL_SURFACE_ATLAS_TILE_NORMAL_THRESHOLD);
if (normalWeight <= 0.0f)
return 0;
// Get tile UV and depth at the world position
float3 tilePosition = mul(float4(worldPosition, 1), tile.WorldToLocal).xyz;
float tileDepth = tilePosition.z / tile.ViewBoundsSize.z;
float2 tileUV = (tilePosition.xy / tile.ViewBoundsSize.xy) + 0.5f;
tileUV.y = 1.0 - tileUV.y;
float2 atlasUV = tileUV * tile.AtlasRectUV.zw + tile.AtlasRectUV.xy;
// Calculate bilinear weights
float4 bilinearWeights;
bilinearWeights.x = (1.0 - tileUV.x) * (tileUV.y);
bilinearWeights.y = (tileUV.x) * (tileUV.y);
bilinearWeights.z = (tileUV.x) * (1 - tileUV.y);
bilinearWeights.w = (1 - tileUV.x) * (1 - tileUV.y);
bilinearWeights = saturate(bilinearWeights);
// Tile depth weight based on sample position occlusion
float4 tileZ = depth.Gather(SamplerLinearClamp, atlasUV, 0.0f);
float depthThreshold = 2.0f * surfaceThreshold / tile.ViewBoundsSize.z;
float4 depthVisibility = 1.0f;
UNROLL
for (uint i = 0; i < 4; i++)
depthVisibility[i] = 1.0f - saturate((abs(tileDepth - tileZ[i]) - depthThreshold) / (0.5f * depthThreshold));
float sampleWeight = normalWeight * dot(depthVisibility, bilinearWeights);
if (sampleWeight <= 0.0f)
return 0;
bilinearWeights = depthVisibility * bilinearWeights;
//bilinearWeights = normalize(bilinearWeights);
// Sample atlas texture
float3 sampleColor = SampleGlobalSurfaceAtlasTex(atlas, atlasUV, bilinearWeights);
//return float4(sampleWeight.xxx, sampleWeight);
return float4(sampleColor.rgb * sampleWeight, sampleWeight);
//return float4(normalWeight.xxx, sampleWeight);
}
// Samples the Global Surface Atlas and returns the lighting (with opacity) at the given world location (and direction).
float4 SampleGlobalSurfaceAtlas(const GlobalSurfaceAtlasData data, Buffer<float4> objects, Texture2D depth, Texture2D atlas, float3 worldPosition, float3 worldNormal)
{
float4 result = float4(0, 0, 0, 0);
float surfaceThreshold = 10.0f; // Additional threshold between object or tile size compared with input data (error due to SDF or LOD incorrect appearance)
float surfaceThreshold = 20.0f; // Additional threshold between object or tile size compared with input data (error due to SDF or LOD incorrect appearance)
// TODO: add grid culling to object for faster lookup
LOOP
for (uint objectIndex = 0; objectIndex < data.ObjectsCount && result.a <= 0.0f; objectIndex++)
@@ -96,42 +149,34 @@ float4 SampleGlobalSurfaceAtlas(const GlobalSurfaceAtlasData data, Buffer<float4
float3 localExtent = object.Extent + surfaceThreshold;
if (any(localPosition > localExtent) || any(localPosition < -localExtent))
continue;
float3 localNormal = normalize(mul(worldNormal, (float3x3)object.WorldToLocal));
// Pick tiles to sample based on the directionality
// Sample tiles based on the directionality
// TODO: place enabled tiles mask in object data to skip reading disabled tiles
// TODO: sample 1/2/3 tiles with weight based on sample normal
uint tileIndex = 2;
GlobalSurfaceTile tile = LoadGlobalSurfaceAtlasTile(objects, objectIndex, tileIndex);
// Tile normal weight based on the sampling angle
float3 tileNormal = normalize(mul(worldNormal, (float3x3)tile.WorldToLocal));
float normalWeight = saturate(dot(float3(0, 0, -1), tileNormal));
normalWeight = (normalWeight - GLOBAL_SURFACE_ATLAS_TILE_NORMAL_THRESHOLD) / (1.0f - GLOBAL_SURFACE_ATLAS_TILE_NORMAL_THRESHOLD);
if (normalWeight <= 0.0f)
continue;
// Get tile UV and depth at the world position
float3 tilePosition = mul(float4(worldPosition, 1), tile.WorldToLocal).xyz;
float tileDepth = tilePosition.z / tile.ViewBoundsSize.z;
float2 tileUV = (tilePosition.xy / tile.ViewBoundsSize.xy) + 0.5f;
tileUV.y = 1.0 - tileUV.y;
float2 atlasCoord = tileUV * tile.AtlasRect.zw + tile.AtlasRect.xy;
// Tile depth weight based on sample position occlusion
// TODO: gather 4 depth samples to smooth weight (depth weight per-sample used late for bilinear weights)
float tileZ = depth.Load(int3(atlasCoord, 0)).x;
float depthThreshold = 2.0f * surfaceThreshold / tile.ViewBoundsSize.z;
float depthWeight = 1.0f - saturate((abs(tileDepth - tileZ) - depthThreshold) / (0.5f * depthThreshold));
if (depthWeight <= 0.0f)
continue;
// Sample atlas texture
// TODO: separate GatherRed/Blue/Green with bilinear weights
float4 color = atlas.Load(int3(atlasCoord, 0));
// TODO: implement Global Surface Atlas sampling
result = float4(color.rgb, 1);
float3 localNormal = normalize(mul(worldNormal, (float3x3)object.WorldToLocal));
float3 localNormalSq = localNormal * localNormal;
if (localNormalSq.x > GLOBAL_SURFACE_ATLAS_TILE_NORMAL_THRESHOLD * GLOBAL_SURFACE_ATLAS_TILE_NORMAL_THRESHOLD)
{
uint tileIndex = localNormal.x > 0.0f ? 0 : 1;
GlobalSurfaceTile tile = LoadGlobalSurfaceAtlasTile(objects, objectIndex, tileIndex);
result += SampleGlobalSurfaceAtlasTile(tile, depth, atlas, worldPosition, worldNormal, surfaceThreshold);
}
if (localNormalSq.y > GLOBAL_SURFACE_ATLAS_TILE_NORMAL_THRESHOLD * GLOBAL_SURFACE_ATLAS_TILE_NORMAL_THRESHOLD)
{
uint tileIndex = localNormal.y > 0.0f ? 2 : 3;
GlobalSurfaceTile tile = LoadGlobalSurfaceAtlasTile(objects, objectIndex, tileIndex);
result += SampleGlobalSurfaceAtlasTile(tile, depth, atlas, worldPosition, worldNormal, surfaceThreshold);
}
if (localNormalSq.z > GLOBAL_SURFACE_ATLAS_TILE_NORMAL_THRESHOLD * GLOBAL_SURFACE_ATLAS_TILE_NORMAL_THRESHOLD)
{
uint tileIndex = localNormal.z > 0.0f ? 4 : 5;
GlobalSurfaceTile tile = LoadGlobalSurfaceAtlasTile(objects, objectIndex, tileIndex);
result += SampleGlobalSurfaceAtlasTile(tile, depth, atlas, worldPosition, worldNormal, surfaceThreshold);
}
}
// Normalize result
result.rgb /= max(result.a, 0.0001f);
return result;
}