LibTessDotNet

Goal

Provide a robust and fast tessellator (polygons with N vertices in the output) for .NET, also does triangulation.

Requirements

• .NET framework 2.0 (pure CLR, should work with Mono, Unity or XNA)
• C# 3.0 compiler if you want to compile (I am guilty of using 'var')
  • WinForms for the testbed
  • Solution file for Visual Studio 2010

Features

• Tessellate arbitrary complex polygons
  • self-intersecting (see "star-intersect" sample)
  • with coincident vertices (see "clipper" sample)
  • advanced winding rules : even/odd, non zero, positive, negative, |winding| >= 2 (see "redbook-winding" sample)
• Custom input
  • Custom vertex attributes (eg. UV coordinates) with merging callback
  • Force orientation of input contour (clockwise/counterclockwise, eg. for GIS systems, see "force-winding" sample)
• Choice of output
  • polygons with N vertices (with N >= 3)
  • connected polygons (didn't quite tried this yet, but should work)
  • boundary only (to have a basic union of two contours)
• Handles polygons computed with Clipper - an open source freeware polygon clipping library
• Single/Double precision support

Screenshot

Comparison

Notes

• When using ElementType.BoundaryContours, Tess.Elements will contain a list of ranges [startVertexIndex, vertexCount]. Those ranges are to used with Tess.Vertices.

TODO

• Profile GC allocations
• Any suggestions are welcome ;)

License

SGI FREE SOFTWARE LICENSE B (Version 2.0, Sept. 18, 2008) More information in LICENSE.txt.

Links

• Reference implementation - the original SGI reference implementation
• libtess2 - Mikko Mononen cleaned up the original GLU tesselator
• Poly2Tri - another triangulation library for .NET (other ports also available)
  • Does not support polygons from Clipper, more specifically vertices with same coordinates (coincident)
• Clipper - an open source freeware polygon clipping library