correct pdf method for mat system, added shouldDoMIS for ray payload

Author: keptsecret

include/nbl/builtin/hlsl/path_tracing/concepts.hlsl

@@ -58,6 +58,7 @@ NBL_CONCEPT_END(
     ((NBL_CONCEPT_REQ_EXPR_RET_TYPE)((ray.init(v/*origin*/, v/*direction*/)), ::nbl::hlsl::is_same_v, void))
     ((NBL_CONCEPT_REQ_EXPR_RET_TYPE)((ray.template initInteraction<impl::DummyInteraction>(interaction)), ::nbl::hlsl::is_same_v, void))
     ((NBL_CONCEPT_REQ_EXPR_RET_TYPE)((ray.initPayload()), ::nbl::hlsl::is_same_v, void))
+    ((NBL_CONCEPT_REQ_EXPR_RET_TYPE)((ray.shouldDoMIS()), ::nbl::hlsl::is_same_v, bool))
     ((NBL_CONCEPT_REQ_EXPR_RET_TYPE)((ray.foundEmissiveMIS(scalar)), ::nbl::hlsl::is_same_v, typename T::spectral_type))
     ((NBL_CONCEPT_REQ_EXPR_RET_TYPE)((ray.addPayloadContribution(color)), ::nbl::hlsl::is_same_v, void))
     ((NBL_CONCEPT_REQ_EXPR_RET_TYPE)((ray.getPayloadAccumulatiion()), ::nbl::hlsl::is_same_v, typename T::spectral_type))

include/nbl/builtin/hlsl/path_tracing/unidirectional.hlsl

@@ -68,12 +68,11 @@ struct Unidirectional
             measure_type emissive = materialSystem.getEmission(matID, interaction);
 
             const typename nee_type::light_id_type lightID = matLightID.getLightID();
-            if (matLightID.isLight())
+            if (ray.shouldDoMIS() && matLightID.isLight())
             {
                 const scalar_type pdf = nee.deferred_pdf(scene, lightID, ray);
                 assert(!hlsl::isinf(pdf));
-                const scalar_type pdfSq = hlsl::mix(pdf, pdf * pdf, pdf < numeric_limits<scalar_type>::max);
-                emissive *= ray.foundEmissiveMIS(pdfSq);
+                emissive *= ray.foundEmissiveMIS(pdf * pdf);
             }
             ray.addPayloadContribution(emissive);
         }
@@ -120,9 +119,9 @@ struct Unidirectional
 
             if (neeContrib.pdf > scalar_type(0.0))
             {
-                quotient_pdf_type bsdf_quotient_pdf = materialSystem.quotient_and_pdf(matID, nee_sample, interaction, _cache);
+                const scalar_type bsdf_pdf = materialSystem.pdf(matID, nee_sample, interaction, _cache);
                 neeContrib.quotient *= materialSystem.eval(matID, nee_sample, interaction, _cache) * rcpChoiceProb;
-                const scalar_type otherGenOverLightAndChoice = bsdf_quotient_pdf.pdf * rcpChoiceProb / neeContrib.pdf;
+                const scalar_type otherGenOverLightAndChoice = bsdf_pdf * rcpChoiceProb / neeContrib.pdf;
                 neeContrib.quotient /= 1.f + otherGenOverLightAndChoice * otherGenOverLightAndChoice;   // balance heuristic
 
                 const vector3_type origin = intersectP;