pdf should return inf when smooth cook torrance bxdf

Author: keptsecret

include/nbl/builtin/hlsl/bxdf/base/cook_torrance_base.hlsl

@@ -139,7 +139,7 @@ struct SCookTorrance
 
             quant_type D = ndf.template D<sample_type, Interaction, MicrofacetCache>(qq, _sample, interaction, cache);
             scalar_type DG = D.projectedLightMeasure;
-            if (D.microfacetMeasure < numeric_limits<scalar_type>::infinity)
+            if (D.microfacetMeasure < bit_cast<scalar_type>(numeric_limits<scalar_type>::infinity))
             {
                 g2g1_query_type gq = ndf.template createG2G1Query<sample_type, Interaction>(_sample, interaction);
                 DG *= ndf.template correlated<sample_type, Interaction>(gq, _sample, interaction);

include/nbl/builtin/hlsl/bxdf/ndf/beckmann.hlsl

@@ -90,7 +90,7 @@ struct BeckmannCommon<T,false NBL_PARTIAL_REQ_BOT(concepts::FloatingPointScalar<
         scalar_type NdotH2 = cache.getNdotH2();
         scalar_type nom = exp2<scalar_type>((NdotH2 - scalar_type(1.0)) / (log<scalar_type>(2.0) * a2 * NdotH2));
         scalar_type denom = a2 * NdotH2 * NdotH2;
-        return numbers::inv_pi<scalar_type> * nom / denom;
+        return hlsl::mix(bit_cast<scalar_type>(numeric_limits<scalar_type>::infinity), numbers::inv_pi<scalar_type> * nom / denom, a2 > numeric_limits<scalar_type>::min);
     }
 
     template<class Query NBL_FUNC_REQUIRES(beckmann_concepts::DG1Query<Query>)
@@ -146,7 +146,7 @@ struct BeckmannCommon<T,true NBL_PARTIAL_REQ_BOT(concepts::FloatingPointScalar<T
         scalar_type NdotH2 = cache.getNdotH2();
         scalar_type nom = exp<scalar_type>(-(cache.getTdotH2() / ax2 + cache.getBdotH2() / ay2) / NdotH2);
         scalar_type denom = a2 * NdotH2 * NdotH2;
-        return numbers::inv_pi<scalar_type> * nom / denom;
+        return hlsl::mix(bit_cast<scalar_type>(numeric_limits<scalar_type>::infinity), numbers::inv_pi<scalar_type> * nom / denom, a2 > numeric_limits<scalar_type>::min);
     }
 
     template<class Query NBL_FUNC_REQUIRES(beckmann_concepts::DG1Query<Query>)

include/nbl/builtin/hlsl/bxdf/ndf/ggx.hlsl

@@ -91,7 +91,7 @@ struct GGXCommon<T,IsBSDF,false NBL_PARTIAL_REQ_BOT(concepts::FloatingPointScala
     scalar_type D(NBL_CONST_REF_ARG(MicrofacetCache) cache)
     {
         scalar_type denom = scalar_type(1.0) - one_minus_a2 * cache.getNdotH2();
-        return a2 * numbers::inv_pi<scalar_type> / (denom * denom);
+        return hlsl::mix(bit_cast<scalar_type>(numeric_limits<scalar_type>::infinity), a2 * numbers::inv_pi<scalar_type> / (denom * denom), a2 > numeric_limits<scalar_type>::min);
     }
 
     template<class Query NBL_FUNC_REQUIRES(ggx_concepts::DG1Query<Query>)
@@ -173,7 +173,7 @@ struct GGXCommon<T,IsBSDF,true NBL_PARTIAL_REQ_BOT(concepts::FloatingPointScalar
     scalar_type D(NBL_CONST_REF_ARG(MicrofacetCache) cache)
     {
         scalar_type denom = cache.getTdotH2() / ax2 + cache.getBdotH2() / ay2 + cache.getNdotH2();
-        return numbers::inv_pi<scalar_type> / (a2 * denom * denom);
+        return hlsl::mix(bit_cast<scalar_type>(numeric_limits<scalar_type>::infinity), numbers::inv_pi<scalar_type> / (a2 * denom * denom), a2 > numeric_limits<scalar_type>::min);
     }
 
     // TODO: potential idea for making GGX spin using covariance matrix of sorts: https://www.desmos.com/3d/weq2ginq9o