Fix numeric error

Author: yozhijk

RadeonRays/src/kernels/CL/common.cl

@@ -174,10 +174,16 @@ float fast_intersect_triangle(ray r, float3 v1, float3 v2, float3 v3, float t_ma
     float3 const e2 = v3 - v1;
     float3 const s1 = cross(r.d.xyz, e2);
 
+    float denom = dot(s1, e1);
+    if (denom == 0.f)
+    {
+        return t_max;
+    }
+    
 #ifdef USE_SAFE_MATH
-    float const invd = 1.f / dot(s1, e1);
+    float const invd = 1.f / denom;
 #else
-    float const invd = native_recip(dot(s1, e1));
+    float const invd = native_recip(denom);
 #endif
 
     float3 const d = r.o.xyz - v1;