CCGSubSurf
Catmull-Clark Gridding Subdivision Surface Library
Randomly perturbed grid with subdivision surface. Coloring shows areas that have been recently recalculated by incremental subdivision.
CCGSubSurf is a public domain library for working with Catmull-Clark subdivision surfaces. It is based on a novel algorithm for computing the subdivision surface that I have developed and refined over several years. Some details of the algorithm are available below and I hope to provide a detailed article at some point. For the time being the source is the definitive reference.
Features
- Easy-to-use: The library has been designed to make integration into existing 3D modelling applications as simple as possible without sacrificing functionality or performance.
- Incremental: CCGSubSurf uses an incremental algorithm to only recalculate the portions of the subsurf that change in response to edits. For dense meshes this gives a potentially unbounded improvement in interactivity.
- Lightweight: Efforts have been made to keep the memory footprint of the subdivision data structures as small as possible. For high levels of subdivision the memory use is close to minimal (although supporting incremental recalculation does have a certain cost).
- Fast: Even disregarding the speed improvement from incremental calculation the library is still very fast, especially at higher subdivision levels. Although primarily intended for interactive (editing) applications, it is fast enough to be a viable alternative for applications that merely need to compute a subdivided surface.
Missing Features
- Creasing: There is currently no support for creasing. In my mind this is the largest problem with the library as stands and I hope to correct it sometime in the future.
- Interactivity Improvements: There is a bit of room for more improvements targetted at interactive applications, for example providing hooks for progress reporting or allowing the subdivision to be aborted and then restarted (after mutating the mesh) in order to support zero-lag editing.
- Adaptive: The library does not support adaptive subdivision. I believe that I can integrate it efficiently into the algorithm but have not spent a considerable amount of time or thought on the issue. At the moment it is on the wishlist, but since I have qualms about adaptive subdivision in general it is not near the top of the list.