feat: simplify BRDF to exclude incoming irradiance

src/examples/brdfs/01_lambert/fragment.glsl

@@ -18,6 +18,7 @@ uniform sampler2D albedoMap;
 
 void main() {
 
+  vec3 ambient = vec3(0.0);
   vec3 albedo = albedoModulator * sRGBToLinear( texture2D( albedoMap, v_uv0 ).rgb );
 
   PunctualLight punctualLight;
@@ -36,8 +37,11 @@ void main() {
   DirectIllumination directIllumination;
   pointLightToDirectIllumination( surface, punctualLight, directIllumination );
 
- vec3 outputColor = vec3(0.0);
-  outputColor += BRDF_Diffuse_Lambert( directIllumination, surface, albedo );
+  vec3 lightDirection = directIllumination.lightDirection;
+  vec3 irradiance = directIllumination.color * saturate( dot( surface.normal, lightDirection ) );
+
+  vec3 outputColor = vec3(0.0);
+  outputColor += ( irradiance + ambient ) * BRDF_Diffuse_Lambert( albedo );
 
   gl_FragColor.rgb = linearTosRGB( outputColor );
   gl_FragColor.a = 1.0;

src/examples/brdfs/02_specular/fragment.glsl

@@ -23,10 +23,11 @@ uniform sampler2D specularRoughnessMap;
 
 void main() {
 
+  vec3 ambient = vec3( 0.0 );
   vec3 albedo = albedoModulator * sRGBToLinear( texture2D( albedoMap, v_uv0 ).rgb );
   vec3 specular = specularModulator * vec3( length( texture2D( specularMap, v_uv0 ).rgb ) );
   float specularRoughness = specularRoughnessModulator * sRGBToLinear( texture2D( specularRoughnessMap, v_uv0 ).rgb ).r;
-  vec3 F0 = ( specular * specular ) * 0.16;
+  vec3 specularF0 = ( specular * specular ) * 0.16;
 
   Surface surface;
   surface.position = v_viewSurfacePosition;
@@ -41,9 +42,12 @@ void main() {
   DirectIllumination directIllumination;
   pointLightToDirectIllumination( surface, punctualLight, directIllumination );
 
+  vec3 lightDirection = directIllumination.lightDirection;
+  vec3 irradiance = directIllumination.color * saturate( dot( surface.normal, lightDirection ) );
+
   vec3 outputColor = vec3(0.0);
-  outputColor += BRDF_Specular_GGX( directIllumination, surface, F0, specularRoughness );
-  outputColor += BRDF_Diffuse_Lambert( directIllumination, surface, albedo );
+  outputColor += irradiance * BRDF_Specular_GGX( surface, lightDirection, specularF0, specularRoughness );
+  outputColor += ( irradiance + ambient ) * BRDF_Diffuse_Lambert( albedo );
 
   gl_FragColor.rgb = linearTosRGB( outputColor );
   gl_FragColor.a = 1.0;

src/examples/brdfs/03_specularAnisotropic/fragment.glsl

@@ -20,11 +20,12 @@ uniform sampler2D specularAnisotropicFlowMap;
 
 void main() {
 
+  vec3 ambient = vec3(0.0);
   vec3 albedo = vec3( 1.0 );
   vec3 specular = vec3( 1.0 );
   float specularRoughness = 0.25;
   vec2 specularAnisotropicFlow = specularAnisotropicFlowModulator * decodeAnisotropyFlowMap( texture2D( specularAnisotropicFlowMap, v_uv0 ) );
-  vec3 F0 = ( specular * specular ) * 0.16;
+  vec3 specularF0 = ( specular * specular ) * 0.16;
 
   Surface surface;
   surface.position = v_viewSurfacePosition;
@@ -44,9 +45,12 @@ void main() {
 
   specularAnisotropicBentNormal( surface, length( specularAnisotropicFlow ), specularRoughness );
 
+  vec3 lightDirection = directIllumination.lightDirection;
+  vec3 irradiance = directIllumination.color * saturate( dot( surface.normal, lightDirection ) );
+
   vec3 outputColor = vec3(0.0);
-  outputColor += BRDF_Specular_GGX( directIllumination, surface, F0, specularRoughness );
-  outputColor += BRDF_Diffuse_Lambert( directIllumination, surface, albedo );
+  outputColor += irradiance * BRDF_Specular_GGX( surface, lightDirection, specularF0, specularRoughness );
+  outputColor += ( irradiance + ambient ) * BRDF_Diffuse_Lambert( albedo );
 
   gl_FragColor.rgb = linearTosRGB( outputColor );
   gl_FragColor.a = 1.0;

src/examples/brdfs/04_normals/fragment.glsl

@@ -24,7 +24,7 @@ void main() {
   vec3 albedo = vec3(1.0,1.0,1.0);
   vec3 specular = vec3(1.0);
   float specularRoughness = 0.25;
-  vec3 F0 = ( specular * specular ) * 0.16;
+  vec3 specularF0 = ( specular * specular ) * 0.16;
 
   vec3 normal = vec3( normalModulator, 1.0 ) * ( texture2D( normalMap, v_uv0 ).grb * 2.0 - 1.0 );
 
@@ -44,10 +44,12 @@ void main() {
   DirectIllumination directIllumination;
   pointLightToDirectIllumination( surface, punctualLight, directIllumination );
 
+  vec3 lightDirection = directIllumination.lightDirection;
+  vec3 irradiance = directIllumination.color * saturate( dot( surface.normal, lightDirection ) );
+
   vec3 outputColor = vec3(0.0);
-  outputColor += BRDF_Specular_GGX( directIllumination, surface, F0, specularRoughness );
-  outputColor += BRDF_Diffuse_Lambert( directIllumination, surface, albedo );
-  outputColor += BRDF_Ambient_Basic( ambient, albedo );
+  outputColor += irradiance * BRDF_Specular_GGX( surface, lightDirection, specularF0, specularRoughness );
+  outputColor += ( irradiance + ambient ) * BRDF_Diffuse_Lambert( albedo );
 
   gl_FragColor.rgb = linearTosRGB( outputColor );
   gl_FragColor.a = 1.0;

src/examples/brdfs/05_bump/fragment.glsl

@@ -20,19 +20,20 @@ uniform sampler2D specularRoughnessMap;
 #pragma include <color/spaces/srgb>
 
 void main() {
-  vec2 uv = v_uv0 * 0.5;
-  vec3 albedo = sRGBToLinear( texture2D( albedoMap, uv ).rgb );
+
+  vec3 ambient = vec3(0.0);
+  vec3 albedo = sRGBToLinear( texture2D( albedoMap, v_uv0 ).rgb );
   vec3 specular = vec3(1.0);
-  float specularRoughness = texture2D( specularRoughnessMap, uv ).r;
-  vec3 F0 = ( specular * specular ) * 0.16;
+  float specularRoughness = texture2D( specularRoughnessMap, v_uv0 ).r;
+  vec3 specularF0 = ( specular * specular ) * 0.16;
 
   Surface surface;
   surface.position = v_viewSurfacePosition;
   surface.normal = normalize( v_viewSurfaceNormal );
   surface.viewDirection = normalize( -v_viewSurfacePosition );
 
-  uvToTangentFrame( surface, uv );
-	perturbSurfaceNormal_BumpMap( surface, bumpMap, uv, 4.0 );
+  uvToTangentFrame( surface, v_uv0 );
+	perturbSurfaceNormal_BumpMap( surface, bumpMap, v_uv0, 4.0 );
 
   PunctualLight punctualLight;
   punctualLight.position = pointLightViewPosition;
@@ -42,9 +43,12 @@ void main() {
   DirectIllumination directIllumination;
   pointLightToDirectIllumination( surface, punctualLight, directIllumination );
 
+  vec3 lightDirection = directIllumination.lightDirection;
+  vec3 irradiance = directIllumination.color * saturate( dot( surface.normal, lightDirection ) );
+
   vec3 outputColor = vec3(0.0);
-  outputColor += BRDF_Specular_GGX( directIllumination, surface, F0, specularRoughness );
-  outputColor += BRDF_Diffuse_Lambert( directIllumination, surface, albedo );
+  outputColor += irradiance * BRDF_Specular_GGX( surface, lightDirection, specularF0, specularRoughness );
+  outputColor += ( irradiance + ambient ) * BRDF_Diffuse_Lambert( albedo );
 
   gl_FragColor.rgb = linearTosRGB( outputColor );
   gl_FragColor.a = 1.0;

src/examples/brdfs/05_bump/vertex.glsl

@@ -14,7 +14,7 @@ void main() {
 
   v_viewSurfaceNormal = normalize( ( worldToView * localToWorld * vec4( normalize( position ), 0.0 ) ).xyz );
   v_viewSurfacePosition = ( worldToView * localToWorld * vec4( position, 1.0 ) ).xyz;
-  v_uv0 = uv;
+  v_uv0 = uv * 0.5;
   gl_Position = viewToScreen * vec4( v_viewSurfacePosition, 1.0 );
 
 }

src/examples/brdfs/06_clearcoat/fragment.glsl

@@ -48,11 +48,13 @@ void main() {
   DirectIllumination directIllumination;
   pointLightToDirectIllumination( surface, punctualLight, directIllumination );
 
+  vec3 lightDirection = directIllumination.lightDirection;
+  vec3 irradiance = directIllumination.color * saturate( dot( surface.normal, lightDirection ) );
+
   vec3 outputColor = vec3(0.0);
-  outputColor += BRDF_Specular_GGX( directIllumination, clearCoatSurface, clearCoatF0, clearCoatRoughness );
-  outputColor += BRDF_Specular_GGX( directIllumination, surface, specularF0, specularRoughness );
-  outputColor += BRDF_Diffuse_Lambert( directIllumination, surface, albedo );
-  outputColor += BRDF_Ambient_Basic( ambient, albedo );
+  outputColor += irradiance * BRDF_Specular_GGX( clearCoatSurface, lightDirection, clearCoatF0, clearCoatRoughness );
+  outputColor += irradiance * BRDF_Specular_GGX( surface, lightDirection, specularF0, specularRoughness );
+  outputColor += ( irradiance + ambient ) * BRDF_Diffuse_Lambert( albedo );
 
   gl_FragColor.rgb = linearTosRGB( outputColor );
   gl_FragColor.a = 1.0;

src/lib/shaders/includes/brdfs/diffuse/lambert.glsl

@@ -4,13 +4,9 @@
 
 // three.js
 vec3 BRDF_Diffuse_Lambert(
-  const in DirectIllumination directIllumination,
-  const in Surface surface,
   const in vec3 albedo ) {
 
-  float dotNL = saturate( dot( directIllumination.lightDirection, surface.normal ) );
-
-	return dotNL * directIllumination.color * albedo * RECIPROCAL_PI;
+	return albedo * RECIPROCAL_PI;
 
 } // validated
 

src/lib/shaders/includes/brdfs/specular/ggx.glsl

@@ -5,20 +5,20 @@
 #pragma include "d_ggx"
 
 // GGX Distribution, Schlick Fresnel, GGX-Smith Visibility
-vec3 BRDF_Specular_GGX( const in DirectIllumination directIllumination, const in Surface surface, const in vec3 F0, const in float specularRoughness ) {
+vec3 BRDF_Specular_GGX( const in Surface surface, vec3 lightDirection, const in vec3 F0, const in float specularRoughness ) {
 	float alpha = pow2( specularRoughness ); // UE4's roughness
 
-	vec3 halfDirection = normalize( directIllumination.lightDirection + surface.viewDirection );
+	vec3 halfDirection = normalize( lightDirection + surface.viewDirection );
 
-	float dotNL = saturate( dot( surface.normal, directIllumination.lightDirection ) );
+	float dotNL = saturate( dot( surface.normal, lightDirection ) );
 	float dotNV = saturate( dot( surface.normal, surface.viewDirection ) );
 	float dotNH = saturate( dot( surface.normal, halfDirection ) );
-	float dotLH = saturate( dot( directIllumination.lightDirection, halfDirection ) );
+	float dotLH = saturate( dot( lightDirection, halfDirection ) );
 
 	vec3 F = F_Schlick( F0, dotLH );
 	float G = G_GGX_SmithCorrelated( alpha, dotNL, dotNV );
 	float D = D_GGX( alpha, dotNH );
 
-  return directIllumination.color * dotNL * F * ( G * D );
+  return F * ( G * D );
 
 } // validated