Fix edge case in CorrectShadingNormal().

mmp · Nov 17, 2016 · 494a9c2 · 494a9c2
1 parent d4b7a98
commit 494a9c2
Showing 1 changed file with 4 additions and 4 deletions.
diff --git a/src/integrators/bdpt.cpp b/src/integrators/bdpt.cpp
@@ -56,10 +56,10 @@ Float CorrectShadingNormal(const SurfaceInteraction &isect, const Vector3f &wo,
     if (mode == TransportMode::Importance) {
         Float num = AbsDot(wo, isect.shading.n) * AbsDot(wi, isect.n);
         Float denom = AbsDot(wo, isect.n) * AbsDot(wi, isect.shading.n);
-        if (denom == 0) {
-            Assert(num == 0);
-            return 0;
-        }
+        // wi is occasionally perpendicular to isect.shading.n; this is
+        // fine, but we don't want to return an infinite or NaN value in
+        // that case.
+        if (denom == 0) return 0;
         return num / denom;
     }
     else