fix grazing angle bias in ggx ndf not being applied correctly.

konstatoivanen · konstatoivanen · commit 352ddf57cebc · 2025-01-12T22:14:30.000+02:00
diff --git a/PKRenderer/Content/Shaders/includes/BRDF.glsl b/PKRenderer/Content/Shaders/includes/BRDF.glsl
@@ -231,7 +231,7 @@ float3 Fr_Inverse_GGXVNDF(const float2 Xi, const float3 Ve, const float alpha)
 float3 Fr_Inverse_GGXVNDF_Full(float2 Xi, const float3 normal, const float3 viewdir, const float roughness)
 {
     // prevent grazing angles 
-    Xi *= 0.98f;
+    Xi.x *= 0.98f;
     const float alpha = pow2(roughness);
     const float3x3 basis = make_TBN(normal);
     const float3 Ve = -viewdir * basis;

Original file line number	Diff line number	Diff line change
`@@ -231,7 +231,7 @@ float3 Fr_Inverse_GGXVNDF(const float2 Xi, const float3 Ve, const float alpha)`
`231`	`231`	`float3 Fr_Inverse_GGXVNDF_Full(float2 Xi, const float3 normal, const float3 viewdir, const float roughness)`
`232`	`232`	`{`
`233`	`233`	`// prevent grazing angles`
`234`		`- Xi *= 0.98f;`
	`234`	`+ Xi.x *= 0.98f;`
`235`	`235`	`const float alpha = pow2(roughness);`
`236`	`236`	`const float3x3 basis = make_TBN(normal);`
`237`	`237`	`const float3 Ve = -viewdir * basis;`