minor fixes to ndf

Author: keptsecret

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

@@ -353,8 +353,8 @@ struct SCookTorrance
         fresnel_type _f = impl::getOrientedFresnel<fresnel_type, IsBSDF>::__call(fresnel, interaction.getNdotV());
 
         const bool valid = impl::checkValid<fresnel_type, IsBSDF>::template __call<sample_type, Interaction, MicrofacetCache>(_f, _sample, interaction, cache);
-        // assert(valid);
-        
+        assert(valid);
+
         scalar_type G2_over_G1 = scalar_type(1.0);
         if (_pdf < bit_cast<scalar_type>(numeric_limits<scalar_type>::infinity))
         {

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

@@ -178,7 +178,7 @@ struct BeckmannGenerateH
             scalar_type sample_x = hlsl::max(u.x, scalar_type(1e-6));
             scalar_type theta = hlsl::acos(cosTheta);
             scalar_type fit = 1.0 + theta * (-0.876 + theta * (0.4265 - 0.0594*theta));
-            scalar_type b = c - (1.0 + c) * hlsl::pow(1.0-sample_x, fit);
+            scalar_type b = c - (1.0 + c) * hlsl::pow(scalar_type(1.0)-sample_x, fit);
 
             scalar_type normalization = 1.0 / (1.0 + c + numbers::inv_sqrtpi<scalar_type> * tanTheta * hlsl::exp(-cotTheta*cotTheta));
 
@@ -208,8 +208,8 @@ struct BeckmannGenerateH
         }
 
         scalar_type sinTheta = hlsl::sqrt(1.0 - V.z*V.z);
-        scalar_type cosPhi = sinTheta==0.0 ? 1.0 : hlsl::clamp(V.x/sinTheta, -1.0, 1.0);
-        scalar_type sinPhi = sinTheta==0.0 ? 0.0 : hlsl::clamp(V.y/sinTheta, -1.0, 1.0);
+        scalar_type cosPhi = sinTheta==0.0 ? 1.0 : hlsl::clamp<scalar_type>(V.x/sinTheta, -1.0, 1.0);
+        scalar_type sinPhi = sinTheta==0.0 ? 0.0 : hlsl::clamp<scalar_type>(V.y/sinTheta, -1.0, 1.0);
         //rotate
         scalar_type tmp = cosPhi*slope.x - sinPhi*slope.y;
         slope.y = sinPhi*slope.x + cosPhi*slope.y;

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

@@ -156,7 +156,7 @@ struct GGXGenerateH
         scalar_type t1 = r * hlsl::cos(phi);
         scalar_type t2 = r * hlsl::sin(phi);
         scalar_type s = scalar_type(0.5) * (scalar_type(1.0) + V.z);
-        t2 = hlsl::mix(hlsl::sqrt(scalar_type(1.0) - t1*t1), t2, s);
+        t2 = (1-s) * hlsl::sqrt(scalar_type(1.0) - t1*t1) + t2 * s;
 
         //reprojection onto hemisphere
         //found cases where t1*t1+t2*t2>1.0 due to fp32 precision issues, hence the max