Blender Git Loki

Dynamic Paint: improve UV island border handling in effects.

1. Forcibly symmetrize the neighbor relations, so that if A is neighbor
of B, B is neighbor of A. The existing code is guaranteed to violate
this if texture resolution is different between the sides of a seam.

2. In texture mode dynamic paint adds a 1 pixel wide border around the
islands. These pixels aren't really part of the dynamic paint domain
and thus by design can't have symmetrical neighbor relations. This
means they can't be treated by effects like normal pixels.
The simplest way to handle it in a consistent way is to exclude
them from effects, but add an additional pass that recomputes them
as average of their non-border neighbors, located on both sides of
the seam.