> why not add another type of primitive? how was it called ... > can't remember > windget edges (my english is not good enough to understand what it meant) > (quad) polygon mesh or something ;-)) Winged Edges. Yes, they can easily store ngon meshes. > so we can have edge loops, rings etc ... > > i know that Philip believes they are not needed for such operations ... he > says it works also with other storing types ... They aren't necessary to have, but the winged edge structure just makes it heaps quicker and easier to handle edge based operations, but it is not impossible to do them without that particular data structure.