Convex hulls and mesh boundaries (original) (raw)
Convex hulls and mesh boundaries
If the input is a vertex set (rather than a PSLG), Triangle produces its convex hull as a by-product in the output.poly file if you use the-c switch. There are faster algorithms for finding a two-dimensional convex hull than triangulation, of course, but this one comes for free. In the example below, the file<dots.node> is read, and its convex hull produced in<dots.1.poly>.
triangle -c dots
If the input is an unconstrained mesh (you are using the-r switch but not the-p switch), Triangle produces a list of its boundary edges (including hole boundaries) as a by-product when you use the -c switch. If you also use the -p switch, the output .poly file will contain all the segments from the input .poly file as well.
For example, consider the mesh described by<face.1.node>,<face.1.ele>, and<face.1.poly> (which you saw created on theDelaunay triangulation page).
triangle -rc face.1 triangle -rpc face.1
In each case, the boundary segments can be found in face.2.poly.
