Cycles: Fix wrong shading when some mesh triangle has non-finite coordinate

This is fully unpredictable for artists when one damaged object makes the whole
scene to render incorrectly. This involves two main changes:

- It is not enough to check triangle bounds to be valid when building BVH.
  This is because triangle might have some finite vertices and some non-finite.

- We shouldn't add non-finite triangle area to the overall area for MIS.

1 files changed, 3 insertions, 0 deletions

diff --git a/intern/cycles/render/light.cpp b/intern/cycles/render/light.cpp
index 6a7f985b756..bb73ebd7e41 100644
--- a/intern/cycles/render/light.cpp
+++ b/intern/cycles/render/light.cpp
@@ -345,6 +345,9 @@ void LightManager::device_update_distribution(Device *device, DeviceScene *dscen
 				offset++;
 
 				Mesh::Triangle t = mesh->get_triangle(i);
+				if(!t.valid(&mesh->verts[0])) {
+					continue;
+				}
 				float3 p1 = mesh->verts[t.v[0]];
 				float3 p2 = mesh->verts[t.v[1]];
 				float3 p3 = mesh->verts[t.v[2]];