PBR fixing, episode 572

shaders/lib/shading-pbr.glsl

@@ -24,9 +24,8 @@ struct T_PBRPrecomputed
 float PBR_SchlickFresnel(
 	in float u )
 {
-	const float m = clamp( 1 - u , 0 , 1 ) ,
-	      m2 = m * m;
-	return m2 * m2 * m;
+	const float m = 1 - u , m2 = M_Sqr( m );
+	return M_Sqr( m2 ) * m;
 }
 
 float PBR_GTR2Aniso(
@@ -38,7 +37,7 @@ float PBR_GTR2Aniso(
 {
 	float x = hDotX / ax , y = hDotY / ay ,
 		p = x * x + y * y + nDotH * nDotH;
-	return 1 / ( PI * ax * ay * p * p );
+	return 1 / ( ax * ay * p * p );
 }
 
 float PBR_SmithGGXAniso(
@@ -59,7 +58,7 @@ T_PBRPrecomputed PBR_Precompute(
 {
 	T_PBRPrecomputed rv;
 
-	rv.nDotV = dot( normal , camDir );
+	rv.nDotV = abs( dot( normal , camDir ) ) + 1e-5;
 	rv.fv = PBR_SchlickFresnel( rv.nDotV );
 
 	float tDir = step( .99 , abs( normal.z ) ) ,
@@ -93,19 +92,21 @@ vec3 PBR_Shade(
 	in vec3 lightDir )
 {
 	float nDotL = dot( normal , lightDir );
-	if ( nDotL < 0 || pre.nDotV < 0 ) {
+	if ( nDotL < 0 ) {
 		return vec3( 0 );
 	}
 
 	vec3 halfVec = normalize( lightDir + camDir ) ;
-	float nDotH = dot( normal , halfVec ) ,
-		lDotH = dot( lightDir , halfVec ) ,
+	float nDotH = M_Saturate( dot( normal , halfVec ) ) ,
+		lDotH = M_Saturate( dot( lightDir , halfVec ) ) ,
 
 	// Diffuse fresnel - go from 1 at normal incidence to .5 at grazing
 	// and mix in diffuse retro-reflection based on roughness
 		FL = PBR_SchlickFresnel( nDotL ) ,
-		Fd90 = 0.5 + 2 * lDotH * lDotH * material.roughness ,
-		Fd = mix( 1 , Fd90 , FL ) * mix( 1 , Fd90 , pre.fv ) ,
+		Fd90 = ( 0.5 + 2 * lDotH * lDotH ) * material.roughness ,
+		Fd = ( 1 + ( Fd90 - 1 ) * FL )
+			* ( 1 + ( Fd90 - 1 ) * pre.fv )
+			* ( 1 - 0.51 * material.roughness / 1.51 ) ,
 
 	// Based on Hanrahan-Krueger brdf approximation of isotropic bssrdf
 	// 1.25 scale is used to (roughly) preserve albedo
@@ -124,11 +125,10 @@ vec3 PBR_Shade(
 				pre.ax , pre.ay ) * pre.vgs;
 
 	vec3 Fs = mix( pre.cSpecular , vec3(1) , FH );
-	return nDotL * ( ( ( 1 / PI )
-			* mix( Fd , ss , material.subsurface )
-			* material.cAlbedo /* + Fsheen */)
-			* pow( 1 - material.metallic , 3 )
-		+ Gs * Fs * Ds );
+	return nDotL * ( mix( Fd , ss , material.subsurface )
+			* material.cAlbedo
+			* ( 1 - material.metallic )
+		+ Gs * Fs * Ds ) / PI;
 }
 
 vec3 PBR_Shade(

shaders/lib/utils.glsl

@@ -36,7 +36,7 @@ vec3 M_NormalizeColor(
 float M_Saturate(
 	in float x )
 {
-	return clamp( x , 0 , 1 );
+	return clamp( x , 0. , 1. );
 }
 
 float M_LengthSqr(