From Time Moore, "This submission implements 3 optimizations for meshes. INDEX_MESH turns DrawArrays? style geometry into DrawElements?, uniquifying the vertices in the process. This is useful for certain loaders, like ac3d, which just spit out DrawArrays?. VERTEX_POSTTRANSFORM and VERTEX_PRETRANSFORM optimize mesh triangle and vertex order for the caches on a modern GPU, using Tom Forsyth's algorithm. I describe this and the big difference it makes (38% improvement on a very large mesh) in my blog, http://shiny-dynamics.blogspot.com/2010/03/vertex-cache-optimization-for-osg.html."