more tweaks - direct specular matches filament more closely

1 files changed, 3 insertions, 5 deletions

diff --git a/brdf.cginc b/brdf.cginc
index 70bca86..a12c256 100644
--- a/brdf.cginc
+++ b/brdf.cginc
@@ -47,12 +47,9 @@ float D_GGX(float roughness, float NoH) {
 
   float k = rcp(NoH2) - 1;
   float r2_plus_k = r2 + k;
-  // Not sure why, but not using the factor of PI here makes the specular match
-  // the Unity standard much more closely. Maybe the author was just folding
-  // the 4.0 (historically used to be a PI) into the GGX calculation?
   float denom = NoH4 * r2_plus_k * r2_plus_k;
 
-  return r2 / denom;
+  return r2 / (denom * PI);
 }
 
 // Hammon "PBR Diffuse Lighting for GGX+Smith Microsurfaces"
@@ -208,10 +205,11 @@ float4 brdf(Pbr pbr, LightData data) {
     direct_specular *= data.direct.color * data.direct.NoL;
     direct_specular *= energy_comp;
     direct_specular *= layer_attenuation;
+    direct_specular *= PI;
     direct_specular = max(0, direct_specular);
     specular += direct_specular;
 
-    float Fd = Fd_OrenNayar(pbr.roughness, data.common.NoV, data.direct.NoL, data.direct.LoV) / PI;
+    float Fd = Fd_OrenNayar(pbr.roughness, data.common.NoV, data.direct.NoL, data.direct.LoV);
     float3 direct_diffuse = Fd * (1.0f - pbr.metallic) * pbr.albedo.xyz * data.direct.color;
     direct_diffuse *= layer_attenuation;
     direct_diffuse = max(0, direct_diffuse);