Minor fixes

Author: sergcpp

internal/CoreRef.cpp

@@ -3610,6 +3610,9 @@ void Ray::Ref::SampleLightSource(const fvec4 &P, const fvec4 &T, const fvec4 &B,
         ls.ray_flags = l.ray_visibility;
     }
 
+    if (hsum(ls.col) < FLT_EPS) {
+        ls.pdf = 0.0f;
+    }
     ls.pdf /= factor;
 }
 

internal/CoreSIMD.h

@@ -5931,6 +5931,8 @@ void Ray::NS::SampleLightSource(const fvec<S> P[3], const fvec<S> T[3], const fv
         ++index;
     }
 
+    const ivec<S> temp_mask = simd_cast((ls.col[0] + ls.col[1] + ls.col[2]) < FLT_EPS);
+    where(ray_mask & temp_mask, ls.pdf) = 0.0f;
     where(ray_mask, ls.pdf) /= factor;
 }