Compositor, blur only parts of a render So here's my render:



and here's my compositor node tree:



The green spheres are on a separate layer from the rest of the ship, so I can apply glow and blur effects to them, without affecting the rest of the ship. Why aren't the green spheres covering the holes in the ship mesh?
I think I fixed the issue by substituting the last Mix node with an Alpha Over node. That appears to have gotten rid of the holes, but I don't know why. If anybody's got either an explanation, or another fix, I'd love to hear it.

Thanks!