triangulate can fail if the input polygon has a large number of co-linear vertices

[cwgable]

A know bug exists in the case where your polygon points have a large number of co-linear vertices. It also matters where in the sequence of points the co-linear point are. Not an issue usually when you create a polygon from scratch. It can show up when you are transmitted a polygon with hundreds of point perhaps from some other application.

C Gable spent time trying to find a fix and was unsuccessful (gave up).

Some examples of this bug can be found here:
/scratch/nts/gable/grid_gen/discrete_fractures/remesh_coarsen/debug
-rwxr-x--x 1 gable sft 1086 Mar 3 2015 run_test.scr
-rw-r--r-- 1 gable sft 276 Mar 3 2015 connect.lgi
-rw-r--r-- 1 gable sft 3164 Feb 25 2015 lagrit_part_1_149.lgi
-rw-r--r-- 1 gable sft 3182 Mar 6 2015 lagrit_part_1_149_modify.lgi
-rw-r----- 1 gable sft 7085 Feb 26 2015 make_points.lgi
-rw-r----- 1 gable sft 506 Feb 26 2015 test.lgi