On Jul 5, 2011, at 4:51 AM, Daniel Roßberg wrote: > I'm starting to work on the integration of the facetize feature into > the C++ API. There I need a wrapper for the NMG primitive. Is there > any additional literature available to get a better understanding of > the nature of this object? I've already the "Combinatorial Solid > Geometry, Boundary Representations and Non-Manifold Geometry" from M. > Muuss and L. Butler.
Daniel, NMG is a pretty simple set of structures, although made somewhat cryptic through the shorthand API nomenclature. The API merely reflects the research shorthand that the implementation is based off of, though. The original research may be a little tricky to get your hands on, but there are several papers available in addition to the paper you referenced. There should be citations in the paper you mentioned. NMG is basically an n-manifold implementation of Weiler's radial edge structure as it pertained to solid geometry and CSG (via Euler operators). I believe his original paper, published in an old 1988 CAD journal, was entitled "The Radial-Edge Structure: A Topological Representation for Non-Manifold Geometric Boundary Representations". That was followed on by a lot of other research on how to apply radial edge for solid modeling and analysis purposes. That all became the foundation for the NMG implementation. Here are a couple of the follow-on papers readily available online, I'm sure there are others: http://www.nakl.t.u-tokyo.ac.jp/~masuda/papers/cad93.pdf http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.43.9530&rep=rep1&type=pdf Something to note, most of the API complexity is geared around 3D Euler operators (ton of info on the topic will come up in a web search). The entire point of NMG is solidity so that analysis properties are mathematically / topologically valid. The Euler operators provide a means to *guarantee* topological structure through change. That is, it can be used to ensure that a polygonal mesh encloses a volume ... or that the volume remains "solid" even after various mesh changes are performed ... or that if an object had three holes when you started that it still has three and only three holes ... and ... so on. Cheers! Sean ------------------------------------------------------------------------------ All of the data generated in your IT infrastructure is seriously valuable. Why? It contains a definitive record of application performance, security threats, fraudulent activity, and more. Splunk takes this data and makes sense of it. IT sense. And common sense. http://p.sf.net/sfu/splunk-d2d-c2 _______________________________________________ BRL-CAD Developer mailing list brlcad-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/brlcad-devel
