Add support for reflecting the background directly

src/materials/PhysicalPathTracingMaterial.js

@@ -481,10 +481,10 @@ export class PhysicalPathTracingMaterial extends MaterialBase {
 
 						if ( ! hit ) {
 
-							if ( i == 0 || transmissiveRay ) {
+							if ( i == 0 || transmissiveRay || i == 1 && ! isShadowRay ) {
 
 								gl_FragColor.rgb += sampleBackground( environmentRotation * rayDirection ) * throughputColor;
-								gl_FragColor.a = backgroundAlpha;
+								gl_FragColor.a = i == 1 && ! isShadowRay ? 1.0 : backgroundAlpha;
 
 							} else {
 
@@ -857,7 +857,8 @@ export class PhysicalPathTracingMaterial extends MaterialBase {
 
 								// get the material pdf
 								vec3 sampleColor;
-								float lightMaterialPdf = bsdfResult( outgoing, clearcoatOutgoing, normalize( invBasis * lightSampleRec.direction ), normalize( clearcoatInvBasis * lightSampleRec.direction ), surfaceRec, sampleColor );
+								float specularPdf;
+								float lightMaterialPdf = bsdfResult( outgoing, clearcoatOutgoing, normalize( invBasis * lightSampleRec.direction ), normalize( clearcoatInvBasis * lightSampleRec.direction ), surfaceRec, specularPdf, sampleColor );
 								bool isValidSampleColor = all( greaterThanEqual( sampleColor, vec3( 0.0 ) ) );
 								if ( lightMaterialPdf > 0.0 && isValidSampleColor ) {
 
@@ -887,6 +888,8 @@ export class PhysicalPathTracingMaterial extends MaterialBase {
 
 							}
 
+							// TODO: we pass a shadow ray boolean in here but this needs to be handled per the new ray or even within the
+							// "attenuateHit" function
 							// check if a ray could even reach the surface
 							vec3 attenuatedColor;
 							if (
@@ -897,10 +900,19 @@ export class PhysicalPathTracingMaterial extends MaterialBase {
 
 								// get the material pdf
 								vec3 sampleColor;
-								float envMaterialPdf = bsdfResult( outgoing, clearcoatOutgoing, normalize( invBasis * envDirection ), normalize( clearcoatInvBasis * envDirection ), surfaceRec, sampleColor );
+								float specularPdf;
+								float envMaterialPdf = bsdfResult( outgoing, clearcoatOutgoing, normalize( invBasis * envDirection ), normalize( clearcoatInvBasis * envDirection ), surfaceRec, specularPdf, sampleColor );
 								bool isValidSampleColor = all( greaterThanEqual( sampleColor, vec3( 0.0 ) ) );
 								if ( envMaterialPdf > 0.0 && isValidSampleColor ) {
 
+									// determine whether the ray is a shadow ray so we can use this for specular reflection determination
+									bool isShadowRay = specularPdf < rand();
+									if ( i <= 1 && ! isShadowRay ) {
+
+										envColor = sampleBackground( envDirection );
+
+									}
+
 									// weight the direct light contribution
 									envPdf /= float( lights.count + 1u );
 									float misWeight = misHeuristic( envPdf, envMaterialPdf );

src/shader/shaderMaterialSampling.js

@@ -407,12 +407,10 @@ float bsdfEval( vec3 wo, vec3 clearcoatWo, vec3 wi, vec3 clearcoatWi, SurfaceRec
 
 }
 
-float bsdfResult( vec3 wo, vec3 clearcoatWo, vec3 wi, vec3 clearcoatWi, SurfaceRec surf, out vec3 color ) {
+float bsdfResult( vec3 wo, vec3 clearcoatWo, vec3 wi, vec3 clearcoatWi, SurfaceRec surf, out float specularPdf, out vec3 color ) {
 
 	float[ 4 ] pdf;
 	getLobeWeights( wo, clearcoatWo, surf, pdf );
-
-	float specularPdf;
 	return bsdfEval( wo, clearcoatWo, wi, clearcoatWi, surf, pdf, specularPdf, color );
 
 }