Triangle: -c switch (original) (raw)

The -c switch

Creates segments on the convex hull of the triangulation.
If you are triangulating a vertex set, this switch causes a.poly file to be written, containing all edges in the convex hull.
If you are triangulating a PSLG, this switch specifies that the whole convex hull of the PSLG should be triangulated, regardless of what segments the PSLG has. If you do not use this switch when triangulating a PSLG, it is assumed that you have identified the region to be triangulated by surrounding it with segments of the input PSLG.
Beware: if you are not careful, this switch can cause the introduction of an extremely thin angle between a PSLG segment and a convex hull segment, which can cause overrefinement.
If you are refining a mesh, this switch works differently; it generates the set of boundary edges of the mesh, including boundaries of holes. (This is useful if no .poly file was read.) Detailed information on convex hulls and mesh boundaries.