The set of functions below are intended to be used together in situations like 3D sculpting where we want to apply symmetry constraints within a "brush region of interest (ROI)" SeeUMeshVertexSculptToolfor example usage Computes list of vertices that are mirror-constrained to vertices in VertexROI. If bForceSameSizeWithGaps is true, MirrorVertexROIOut will be the same size as VertexROI, and -1 is stored for vertices in VertexROI that are source vertices or on the symmetry plane. Otherwise those vertices are skipped.