Improve voxel visibility function

CHANGELOG.md

@@ -16,6 +16,7 @@
 - Improved cone tracing direction selection.
 - Removed cone tracing bias.
 - Removed redundant matrix multiplication in voxelization step.
+- Improved voxel visibility function.
 
 ### Fixed
 

ShaderLibrary/Radiances/Pixel.cginc

@@ -35,7 +35,7 @@
       if (notInRange || (spotFalloff <= 0.0) || (data.NdotL <= 0.0)) continue;
 
       radiance +=
-        VoxelVisibility(data.voxelPosition + data.vecN, lightSource.voxelPosition)
+        VXGI_VoxelVisibility((data.voxelPosition + data.vecN) / Resolution, lightSource.voxelPosition / Resolution)
         * GeneralBRDF(data)
         * data.NdotL
         * spotFalloff

ShaderLibrary/Radiances/Sampler.cginc

@@ -1,100 +1,74 @@
-#ifndef VXGI_RADIANCES_SAMPLER
-  #define VXGI_RADIANCES_SAMPLER
+#ifndef VXGI_SHADERLIBRARY_RADIANCES_SAMPLER
+#define VXGI_SHADERLIBRARY_RADIANCES_SAMPLER
 
-  #ifdef RADIANCE_POINT_SAMPLER
-    #define RADIANCE_SAMPLER point_clamp_sampler
-  #else
-    #define RADIANCE_SAMPLER linear_clamp_sampler
-  #endif
-
-  #define LERP_OCCLUSION(level, position, fraction) lerp(SAMPLE_OCCLUSION(level - 1, position), SAMPLE_OCCLUSION(level, position), fraction)
-  #define LERP_RADIANCE(level, position, fraction) lerp(SAMPLE_RADIANCE(level - 1, position), SAMPLE_RADIANCE(level, position), fraction)
-  #define SAMPLE_OCCLUSION(level, position) SAMPLE_RADIANCE(level, position).a
-  #define SAMPLE_RADIANCE(level, position) Radiances[level].SampleLevel(RADIANCE_SAMPLER, position, 0.0)
+#ifdef RADIANCE_POINT_SAMPLER
+  #define RADIANCE_SAMPLER point_clamp_sampler
+#else
+  #define RADIANCE_SAMPLER linear_clamp_sampler
+#endif
 
-  #include "Packages/com.looooong.srp.vxgi/ShaderLibrary/Variables.cginc"
+#define LERP_RADIANCE(level, position, fraction) lerp(SAMPLE_RADIANCE(level - 1, position), SAMPLE_RADIANCE(level, position), fraction)
+#define SAMPLE_RADIANCE(level, position) Radiances[level].SampleLevel(RADIANCE_SAMPLER, position, 0.0)
 
-  Texture3D Radiance0;
-  Texture3D Radiance1;
-  Texture3D Radiance2;
-  Texture3D Radiance3;
-  Texture3D Radiance4;
-  Texture3D Radiance5;
-  Texture3D Radiance6;
-  Texture3D Radiance7;
-  Texture3D Radiance8;
-  static Texture3D Radiances[9] = {
-    Radiance0,
-    Radiance1,
-    Radiance2,
-    Radiance3,
-    Radiance4,
-    Radiance5,
-    Radiance6,
-    Radiance7,
-    Radiance8,
-  };
+#include "Packages/com.looooong.srp.vxgi/ShaderLibrary/Variables.cginc"
 
-  float SampleLevel(float size)
-  {
-    return size <= 1.0 ? size : log2(size) + 1;
-  }
+Texture3D Radiance0;
+Texture3D Radiance1;
+Texture3D Radiance2;
+Texture3D Radiance3;
+Texture3D Radiance4;
+Texture3D Radiance5;
+Texture3D Radiance6;
+Texture3D Radiance7;
+Texture3D Radiance8;
+static Texture3D Radiances[9] = {
+  Radiance0,
+  Radiance1,
+  Radiance2,
+  Radiance3,
+  Radiance4,
+  Radiance5,
+  Radiance6,
+  Radiance7,
+  Radiance8,
+};
 
-  float SampleOcclusion(float3 position, float size)
-  {
-    float level = clamp(SampleLevel(size), 0.0, 8.999999);
-    uint levelFloor = level;
+float SampleLevel(float size)
+{
+  return size <= 1.0 ? size : log2(size) + 1;
+}
 
-    if (level <= 1.0) {
-      return lerp(0.0, SAMPLE_OCCLUSION(0, position), level);
-    } else {
-      switch (levelFloor) {
-      case 1:
-        return LERP_OCCLUSION(1, position, frac(level));
-      case 2:
-        return LERP_OCCLUSION(2, position, frac(level));
-      case 3:
-        return LERP_OCCLUSION(3, position, frac(level));
-      case 4:
-        return LERP_OCCLUSION(4, position, frac(level));
-      case 5:
-        return LERP_OCCLUSION(5, position, frac(level));
-      case 6:
-        return LERP_OCCLUSION(6, position, frac(level));
-      case 7:
-        return LERP_OCCLUSION(7, position, frac(level));
-      default:
-        return LERP_OCCLUSION(8, position, frac(level));
-      }
-    }
-  }
+float VXGI_VoxelOpacity(float3 position)
+{
+  return Radiance0.SampleLevel(RADIANCE_SAMPLER, position, 0.0).a;
+}
 
-  float4 SampleRadiance(float3 position, float size)
-  {
-    float level = clamp(SampleLevel(size), 0.0, 8.999999);
-    uint levelFloor = level;
+float4 SampleRadiance(float3 position, float size)
+{
+  float level = clamp(SampleLevel(size), 0.0, 8.999999);
+  uint levelFloor = level;
 
-    if (level <= 1.0) {
-      return lerp(0.0, SAMPLE_RADIANCE(0, position), level);
-    } else {
-      switch (levelFloor) {
-      case 1:
-        return LERP_RADIANCE(1, position, frac(level));
-      case 2:
-        return LERP_RADIANCE(2, position, frac(level));
-      case 3:
-        return LERP_RADIANCE(3, position, frac(level));
-      case 4:
-        return LERP_RADIANCE(4, position, frac(level));
-      case 5:
-        return LERP_RADIANCE(5, position, frac(level));
-      case 6:
-        return LERP_RADIANCE(6, position, frac(level));
-      case 7:
-        return LERP_RADIANCE(7, position, frac(level));
-      default:
-        return LERP_RADIANCE(8, position, frac(level));
-      }
+  if (level <= 1.0) {
+    return lerp(0.0, SAMPLE_RADIANCE(0, position), level);
+  } else {
+    switch (levelFloor) {
+    case 1:
+      return LERP_RADIANCE(1, position, frac(level));
+    case 2:
+      return LERP_RADIANCE(2, position, frac(level));
+    case 3:
+      return LERP_RADIANCE(3, position, frac(level));
+    case 4:
+      return LERP_RADIANCE(4, position, frac(level));
+    case 5:
+      return LERP_RADIANCE(5, position, frac(level));
+    case 6:
+      return LERP_RADIANCE(6, position, frac(level));
+    case 7:
+      return LERP_RADIANCE(7, position, frac(level));
+    default:
+      return LERP_RADIANCE(8, position, frac(level));
     }
   }
-#endif
+}
+#endif // VXGI_SHADERLIBRARY_RADIANCES_SAMPLER

ShaderLibrary/Radiances/Voxel.cginc

@@ -34,7 +34,7 @@
       if (notInRange || (spotFalloff <= 0.0) || (data.NdotL <= 0.0)) continue;
 
       radiance +=
-        VoxelVisibility(data.voxelPosition + data.vecL / data.NdotL, lightSource.voxelPosition)
+        VXGI_VoxelVisibility((data.voxelPosition + data.vecL / data.NdotL) / Resolution, lightSource.voxelPosition / Resolution)
         * data.NdotL
         * spotFalloff
         * lightSource.Attenuation(localPosition);

ShaderLibrary/Variables.cginc

@@ -1,51 +1,63 @@
-#ifndef VXGI_VARIABLES
-  #define VXGI_VARIABLES
+#ifndef VXGI_SHADERLIBRARY_VARIABLES
+#define VXGI_SHADERLIBRARY_VARIABLES
 
-  #include "Packages/com.looooong.srp.vxgi/ShaderLibrary/Structs/LightSource.hlsl"
+#include "Packages/com.looooong.srp.vxgi/ShaderLibrary/Structs/LightSource.hlsl"
 
-  uint Resolution;
-  uint LightCount;
-  float4x4 VoxelToWorld;
-  float4x4 WorldToVoxel;
-  SamplerState point_clamp_sampler;
-  SamplerState linear_clamp_sampler;
-  StructuredBuffer<LightSource> LightSources;
+uint Resolution;
+uint LightCount;
+float4x4 VoxelToWorld;
+float4x4 WorldToVoxel;
+SamplerState point_clamp_sampler;
+SamplerState linear_clamp_sampler;
+StructuredBuffer<LightSource> LightSources;
 
-  static float ConeDirectionThreshold = sin(atan(1.0/3.0));
+static float ConeDirectionThreshold = sin(atan(1.0/3.0));
 
-  // Cone tracing direction for indirect diffuse calculations
-  static float3 Directions[32] = {
-    float3(+0.000000, +1.000000, +0.000000),
-    float3(+0.000000, -1.000000, +0.000000),
-    float3(+0.000000, +0.187595, -0.982245),
-    float3(+0.000000, -0.187595, +0.982245),
-    float3(+0.000000, +0.745356, -0.666656),
-    float3(+0.000000, -0.745356, +0.666656),
-    float3(+0.000000, +0.794654, +0.607060),
-    float3(+0.000000, -0.794654, -0.607060),
-    float3(+0.356818, +0.333334, +0.872681),
-    float3(+0.356818, -0.333334, -0.872681),
-    float3(-0.356818, +0.333334, +0.872681),
-    float3(-0.356818, -0.333334, -0.872681),
-    float3(+0.525736, +0.794654, -0.303524),
-    float3(+0.525736, -0.794654, +0.303524),
-    float3(-0.525736, +0.794654, -0.303524),
-    float3(-0.525736, -0.794654, +0.303524),
-    float3(+0.577350, +0.333334, -0.745356),
-    float3(+0.577350, -0.333334, +0.745356),
-    float3(-0.577350, +0.333334, -0.745356),
-    float3(-0.577350, -0.333334, +0.745356),
-    float3(+0.577350, +0.745356, +0.333334),
-    float3(+0.577350, -0.745356, -0.333334),
-    float3(-0.577350, +0.745356, +0.333334),
-    float3(-0.577350, -0.745356, -0.333334),
-    float3(+0.850648, +0.187595, +0.491129),
-    float3(+0.850648, -0.187595, -0.491129),
-    float3(-0.850648, +0.187595, +0.491129),
-    float3(-0.850648, -0.187595, -0.491129),
-    float3(+0.934174, +0.333334, -0.127319),
-    float3(+0.934174, -0.333334, +0.127319),
-    float3(-0.934174, +0.333334, -0.127319),
-    float3(-0.934174, -0.333334, +0.127319),
-  };
-#endif
+// Cone tracing direction for indirect diffuse calculations
+static float3 Directions[32] = {
+  float3(+0.000000, +1.000000, +0.000000),
+  float3(+0.000000, -1.000000, +0.000000),
+  float3(+0.000000, +0.187595, -0.982245),
+  float3(+0.000000, -0.187595, +0.982245),
+  float3(+0.000000, +0.745356, -0.666656),
+  float3(+0.000000, -0.745356, +0.666656),
+  float3(+0.000000, +0.794654, +0.607060),
+  float3(+0.000000, -0.794654, -0.607060),
+  float3(+0.356818, +0.333334, +0.872681),
+  float3(+0.356818, -0.333334, -0.872681),
+  float3(-0.356818, +0.333334, +0.872681),
+  float3(-0.356818, -0.333334, -0.872681),
+  float3(+0.525736, +0.794654, -0.303524),
+  float3(+0.525736, -0.794654, +0.303524),
+  float3(-0.525736, +0.794654, -0.303524),
+  float3(-0.525736, -0.794654, +0.303524),
+  float3(+0.577350, +0.333334, -0.745356),
+  float3(+0.577350, -0.333334, +0.745356),
+  float3(-0.577350, +0.333334, -0.745356),
+  float3(-0.577350, -0.333334, +0.745356),
+  float3(+0.577350, +0.745356, +0.333334),
+  float3(+0.577350, -0.745356, -0.333334),
+  float3(-0.577350, +0.745356, +0.333334),
+  float3(-0.577350, -0.745356, -0.333334),
+  float3(+0.850648, +0.187595, +0.491129),
+  float3(+0.850648, -0.187595, -0.491129),
+  float3(-0.850648, +0.187595, +0.491129),
+  float3(-0.850648, -0.187595, -0.491129),
+  float3(+0.934174, +0.333334, -0.127319),
+  float3(+0.934174, -0.333334, +0.127319),
+  float3(-0.934174, +0.333334, -0.127319),
+  float3(-0.934174, -0.333334, +0.127319),
+};
+
+static float3 VXGI_VoxelSizes[] = {
+  1.0 / Resolution,
+  2.0 / Resolution,
+  4.0 / Resolution,
+  8.0 / Resolution,
+  16.0 / Resolution,
+  32.0 / Resolution,
+  64.0 / Resolution,
+  128.0 / Resolution,
+  256.0 / Resolution
+};
+#endif // VXGI_SHADERLIBRARY_VARIABLES

ShaderLibrary/Visibility.cginc

@@ -1,25 +1,28 @@
-#ifndef VXGI_VISIBILITY
-  #define VXGI_VISIBILITY
+#ifndef VXGI_SHADERLIBRARY_VISIBILITY
+#define VXGI_SHADERLIBRARY_VISIBILITY
 
-  #include "Packages/com.looooong.srp.vxgi/ShaderLibrary/Variables.cginc"
-  #include "Packages/com.looooong.srp.vxgi/ShaderLibrary/Utilities.cginc"
-  #include "Packages/com.looooong.srp.vxgi/ShaderLibrary/Radiances/Sampler.cginc"
+#include "Packages/com.looooong.srp.vxgi/ShaderLibrary/Variables.cginc"
+#include "Packages/com.looooong.srp.vxgi/ShaderLibrary/Utilities.cginc"
+#include "Packages/com.looooong.srp.vxgi/ShaderLibrary/Radiances/Sampler.cginc"
 
-  // Calculate visibility between 2 points in voxel space
-  float VoxelVisibility(float3 p1, float3 p2)
-  {
-    float occlusion = 0.0;
-    float3 direction = normalize(p2 - p1);
-    float3 step = direction / Resolution;
+// Calculate visibility between 2 points in voxel space
+float VXGI_VoxelVisibility(float3 p1, float3 p2)
+{
+  uint level = 0;
+  float opacity = 0.0;
+  float stepDistance = distance(p1, p2);
+  float stepSize = 0.5 * VXGI_VoxelSizes[level];
+  float3 stepDirection = normalize(p2 - p1);
+  float3 step = stepSize * stepDirection;
 
-    for (
-      float3 coordinate = p1 / Resolution + step;
-      occlusion < 1.0 && TextureSDF(coordinate) > 0.0 && dot(mad(-coordinate, Resolution, p2), direction) > 0.5;
-      coordinate += 0.5 * step
-    ) {
-      occlusion += (1.0 - occlusion) * SampleOcclusion(coordinate, 1.0);
-    }
-
-    return 1.0 - occlusion;
+  for (
+    p1 += step, stepDistance -= stepSize;
+    opacity < 1.0 && stepDistance > 0.0;
+    p1 += step, stepDistance -= stepSize
+  ) {
+    if (TextureSDF(p1) > 0.0) opacity += (1.0 - opacity) * VXGI_VoxelOpacity(p1);
   }
-#endif
+
+  return 1.0 - opacity;
+}
+#endif // VXGI_SHADERLIBRARY_VISIBILITY