219e655119
In volume segment, the minimal angle formed by the emitter bounding cone axis and the vector pointing from the cluster centroid to any point on the ray is computed via `dot(bcone.axis, point_to_centroid)`, see Fig.8. in paper. For distant light this angle is 0, but due to numerical issues this is not always true. Therefore explicitly assign `-bcone.axis` to `point_to_centroid` in this case. Pull Request: https://projects.blender.org/blender/blender/pulls/129489