`PBVH_Leaf` nodes are now split into a new `PBVH_TexLeaf`
node type when using the paint brush. These nodes are
split by image pixels, not triangles. This greatly
increases performance when working with large
textures on low-poly meshes.
Reviewed By: Jeroen Bakker
Differential Revision: https://developer.blender.org/D14900
Ref: D14900