Merge pull request #22363 from WestLangley/dev_shaders_refactor

Shaders: refactoring

src/renderers/shaders/ShaderChunk/bsdfs.glsl.js

@@ -1,23 +1,5 @@
 export default /* glsl */`
 
-// Analytical approximation of the DFG LUT, one half of the
-// split-sum approximation used in indirect specular lighting.
-// via 'environmentBRDF' from "Physically Based Shading on Mobile"
-// https://www.unrealengine.com/blog/physically-based-shading-on-mobile - environmentBRDF for GGX on mobile
-vec2 integrateSpecularBRDF( const in float dotNV, const in float roughness ) {
-
-	const vec4 c0 = vec4( - 1, - 0.0275, - 0.572, 0.022 );
-
-	const vec4 c1 = vec4( 1, 0.0425, 1.04, - 0.04 );
-
-	vec4 r = roughness * c0 + c1;
-
-	float a004 = min( r.x * r.x, exp2( - 9.28 * dotNV ) ) * r.x + r.y;
-
-	return vec2( - 1.04, 1.04 ) * a004 + r.zw;
-
-}
-
 float punctualLightIntensityToIrradianceFactor( const in float lightDistance, const in float cutoffDistance, const in float decayExponent ) {
 
 #if defined ( PHYSICALLY_CORRECT_LIGHTS )
@@ -118,6 +100,56 @@ vec3 BRDF_Specular_GGX( const in IncidentLight incidentLight, const in vec3 view
 
 } // validated
 
+// Analytical approximation of the DFG LUT, one half of the
+// split-sum approximation used in indirect specular lighting.
+// via 'environmentBRDF' from "Physically Based Shading on Mobile"
+// https://www.unrealengine.com/blog/physically-based-shading-on-mobile
+vec2 DFGApprox( const in vec3 normal, const in vec3 viewDir, const in float roughness ) {
+
+	float dotNV = saturate( dot( normal, viewDir ) );
+
+	const vec4 c0 = vec4( - 1, - 0.0275, - 0.572, 0.022 );
+
+	const vec4 c1 = vec4( 1, 0.0425, 1.04, - 0.04 );
+
+	vec4 r = roughness * c0 + c1;
+
+	float a004 = min( r.x * r.x, exp2( - 9.28 * dotNV ) ) * r.x + r.y;
+
+	vec2 fab = vec2( - 1.04, 1.04 ) * a004 + r.zw;
+
+	return fab;
+
+}
+
+vec3 BRDF_Specular_GGX_Environment( const in vec3 normal, const in vec3 viewDir, const in vec3 specularColor, const in float specularF90, const in float roughness ) {
+
+	vec2 fab = DFGApprox( normal, viewDir, roughness );
+
+	return specularColor * fab.x + specularF90 * fab.y;
+
+}
+
+// Fdez-Agüera's "Multiple-Scattering Microfacet Model for Real-Time Image Based Lighting"
+// Approximates multiscattering in order to preserve energy.
+// http://www.jcgt.org/published/0008/01/03/
+void BRDF_Specular_Multiscattering_Environment( const in vec3 normal, const in vec3 viewDir, const in vec3 specularColor, const in float specularF90, const in float roughness, inout vec3 singleScatter, inout vec3 multiScatter ) {
+
+	vec2 fab = DFGApprox( normal, viewDir, roughness );
+
+	vec3 FssEss = specularColor * fab.x + specularF90 * fab.y;
+
+	float Ess = fab.x + fab.y;
+	float Ems = 1.0 - Ess;
+
+	vec3 Favg = specularColor + ( 1.0 - specularColor ) * 0.047619; // 1/21
+	vec3 Fms = FssEss * Favg / ( 1.0 - Ems * Favg );
+
+	singleScatter += FssEss;
+	multiScatter += Fms * Ems;
+
+}
+
 // Rect Area Light
 
 // Real-Time Polygonal-Light Shading with Linearly Transformed Cosines
@@ -235,38 +267,6 @@ vec3 LTC_Evaluate( const in vec3 N, const in vec3 V, const in vec3 P, const in m
 
 // End Rect Area Light
 
-// ref: https://www.unrealengine.com/blog/physically-based-shading-on-mobile - environmentBRDF for GGX on mobile
-vec3 BRDF_Specular_GGX_Environment( const in vec3 viewDir, const in vec3 normal, const in vec3 specularColor, const in float specularF90, const in float roughness ) {
-
-	float dotNV = saturate( dot( normal, viewDir ) );
-
-	vec2 brdf = integrateSpecularBRDF( dotNV, roughness );
-
-	return specularColor * brdf.x + specularF90 * brdf.y;
-
-} // validated
-
-// Fdez-Agüera's "Multiple-Scattering Microfacet Model for Real-Time Image Based Lighting"
-// Approximates multiscattering in order to preserve energy.
-// http://www.jcgt.org/published/0008/01/03/
-void BRDF_Specular_Multiscattering_Environment( const in GeometricContext geometry, const in vec3 specularColor, const in float specularF90, const in float roughness, inout vec3 singleScatter, inout vec3 multiScatter ) {
-
-	float dotNV = saturate( dot( geometry.normal, geometry.viewDir ) );
-
-	vec2 brdf = integrateSpecularBRDF( dotNV, roughness );
-
-	vec3 FssEss = specularColor * brdf.x + specularF90 * brdf.y;
-
-	float Ess = brdf.x + brdf.y;
-	float Ems = 1.0 - Ess;
-
-	vec3 Favg = specularColor + ( 1.0 - specularColor ) * 0.047619; // 1/21
-	vec3 Fms = FssEss * Favg / ( 1.0 - Ems * Favg );
-
-	singleScatter += FssEss;
-	multiScatter += Fms * Ems;
-
-}
 
 float G_BlinnPhong_Implicit( /* const in float dotNL, const in float dotNV */ ) {
 

src/renderers/shaders/ShaderChunk/lights_physical_pars_fragment.glsl.js

@@ -131,7 +131,7 @@ void RE_IndirectSpecular_Physical( const in vec3 radiance, const in vec3 irradia
 
 		float ccDotNV = saturate( dot( geometry.clearcoatNormal, geometry.viewDir ) );
 
-		reflectedLight.indirectSpecular += clearcoatRadiance * material.clearcoat * BRDF_Specular_GGX_Environment( geometry.viewDir, geometry.clearcoatNormal, vec3( DEFAULT_SPECULAR_COEFFICIENT ), 1.0, material.clearcoatRoughness );
+		reflectedLight.indirectSpecular += clearcoatRadiance * material.clearcoat * BRDF_Specular_GGX_Environment( geometry.clearcoatNormal, geometry.viewDir, vec3( DEFAULT_SPECULAR_COEFFICIENT ), 1.0, material.clearcoatRoughness );
 
 		float ccDotNL = ccDotNV;
 		float clearcoatDHR = material.clearcoat * clearcoatDHRApprox( material.clearcoatRoughness, ccDotNL );
@@ -150,7 +150,7 @@ void RE_IndirectSpecular_Physical( const in vec3 radiance, const in vec3 irradia
 	vec3 multiScattering = vec3( 0.0 );
 	vec3 cosineWeightedIrradiance = irradiance * RECIPROCAL_PI;
 
-	BRDF_Specular_Multiscattering_Environment( geometry, material.specularColor, material.specularF90, material.specularRoughness, singleScattering, multiScattering );
+	BRDF_Specular_Multiscattering_Environment( geometry.normal, geometry.viewDir, material.specularColor, material.specularF90, material.specularRoughness, singleScattering, multiScattering );
 
 	vec3 diffuse = material.diffuseColor * ( 1.0 - ( singleScattering + multiScattering ) );
 

src/renderers/shaders/ShaderChunk/transmission_pars_fragment.glsl.js

@@ -106,11 +106,7 @@ export default /* glsl */`
 		vec3 attenuatedColor = applyVolumeAttenuation( transmittedLight, length( transmissionRay ), attenuationColor, attenuationDistance );
 
 		// Get the specular component.
-		float dotNV = saturate( dot( n, v ) );
-
-		vec2 brdf = integrateSpecularBRDF( dotNV, roughness );
-
-		vec3 F = specularColor * brdf.x + specularF90 * brdf.y;
+		vec3 F = BRDF_Specular_GGX_Environment( n, v, specularColor, specularF90, roughness );
 
 		return ( 1.0 - F ) * attenuatedColor * diffuseColor;