triangle -p

Reads a Planar Straight Line Graph (.poly file), which can specify vertices, segments, holes, regional attributes, and regional area constraints. Generates a constrained Delaunay triangulation (CDT) fitting the input; or, if -s, -q, -a, or -u is used, a conforming constrained Delaunay triangulation (CCDT). If you want a truly Delaunay (not just constrained Delaunay) triangulation, use -D as well. When -p is not used, Triangle reads a .node file by default.