Fix normal filtering, which fixes both IBL and direct lighting flashing

1 files changed, 13 insertions, 15 deletions

diff --git a/pbr.cginc b/pbr.cginc
index f3c46a5..33264ce 100755
--- a/pbr.cginc
+++ b/pbr.cginc
@@ -94,31 +94,28 @@ float2 parallax_offset(float2 uv, float3 view_dir_world, float3x3 tbn) {
 }
 #endif  // _PARALLAX_HEIGHTMAP
 
-// Tokuyashi and Kaplanyan 2019 "Improved Geometric Specular Antialiasing"
-float normalFiltering(float3 normal, float perceptual_roughness) {
-  float3 du = ddx(normal);
-  float3 dv = ddy(normal);
+// Tokuyoshi and Kaplanyan 2019 "Improved Geometric Specular Antialiasing"
+float normalFiltering(float3 geometric_normal, float perceptual_roughness) {
+  float3 du = ddx(geometric_normal);
+  float3 dv = ddy(geometric_normal);
 
-  // Boxed equation in section 3.2 "Proposed Error Reduction."
-  float variance = dot(du, du) + dot(dv, dv);
-  float sigma = 0.5f;  // standard deviation of pixel filter kernel in image space
-  float Sigma = sigma * sigma * variance;
-
-  // Equation 1 in section 4.2 "Constraint for Conservative Isotropic Filtering"
+  float variance = _Specular_AA_Variance * (dot(du, du) + dot(dv, dv));
   float roughness = perceptual_roughness * perceptual_roughness;
-  float kappa = 0.18;
-  roughness = roughness + min(2 * Sigma, kappa);
+  float kernel_roughness = min(2.0f * variance, _Specular_AA_Threshold);
+  float square_roughness = saturate(roughness * roughness + kernel_roughness);
 
-  return saturate(sqrt(roughness));
+  return saturate(sqrt(sqrt(square_roughness)));
 }
 
 void propagateSmoothness(inout Pbr pbr) {
-  pbr.smoothness = 1.0f - normalFiltering(pbr.normal, 1.0f - pbr.smoothness);
+  pbr.smoothness = 1.0f - normalFiltering(pbr.geometric_normal, 1.0f - pbr.smoothness);
 
   pbr.roughness_perceptual = clamp(1.0f - pbr.smoothness, MIN_PERCEPTUAL_ROUGHNESS, 1);
   pbr.roughness = clamp(pbr.roughness_perceptual * pbr.roughness_perceptual, MIN_ROUGHNESS, 1);
 #if defined(_CLEARCOAT)
-  pbr.cc_roughness = max(MIN_ROUGHNESS, pbr.cc_roughness * pbr.cc_roughness);
+  pbr.cc_roughness_perceptual = clamp(pbr.cc_roughness_perceptual, MIN_PERCEPTUAL_ROUGHNESS, 1);
+  pbr.cc_roughness_perceptual = normalFiltering(pbr.geometric_normal, pbr.cc_roughness_perceptual);
+  pbr.cc_roughness = max(MIN_ROUGHNESS, pbr.cc_roughness_perceptual * pbr.cc_roughness_perceptual);
 #endif
 }
 
@@ -181,6 +178,7 @@ Pbr getPbr(v2f i) {
   Pbr pbr = (Pbr) 0;
 
   float3 n = i.normal;
+  pbr.geometric_normal = n;
   float3 t = i.tangent.xyz;
   t = normalize(t - n * dot(n, t));  // Gram-Schmidt to avoid skew
   float3 b = normalize(cross(n, t)) * i.tangent.w;