On The Degree of Vertices in a Shadow Volume Silhouette

Tomas Akenine-Möller
Lund Institute of Technology

Ulf Assarsson
Chalmers University of Technology

This paper appears in issue Volume 8, Number 4.
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Abstract

In shadow volume rendering, the shadow volume silhouette edges are used to create primitives that model the shadow volume. A common misconception is that the vertices on such silhouettes can only be connected to two silhouette edges, i.e., have degree two. Furthermore, some believe that such a vertex can have any degree. In this short note, we present a geometric proof that shows that the degree of a silhouette vertex must be even, and not necessarily two.

Author Information

Tomas Akenine-Möller, Lund, Sweden tam@cs.lth.se

Ulf Assarsson, Gothenberg, Sweden uffe@ce.chalmers.se

BibTeX Entry

@article{AkenineMollerAssarsson03,
  author = "Tomas Akenine-Möller and Ulf Assarsson",
  title = "On The Degree of Vertices in a Shadow Volume Silhouette",
  journal = "journal of graphics, gpu, and game tools",
  volume = "8",
  number = "4",
  pages = "21-24",
  year = "2003",
}