Mesh Library Cleanup

by Clouddrift for BRL-CAD

BRL-CAD has an extensive n-manifold (NMG) polygonal mesh library presently embedded within LIBRT. This part in BRL-CAD runs good but not perfect, for it is far from, as is expected, stable, rubost and easy-read. Sometimes it causes some awkward performance problem and some algorithm based on current NMG is inefficient. The purpose of this project is to clean, validate and verify relevant source code about NMG, and then add the missing Euler Operation to it.