Triangle: -S switch

The -S switch

Specifies the maximum number of Steiner points that may be inserted into the mesh (to meet the constraints on minimum angle and maximum area). Type an integer after the -S switch.
The default (when -S is not used) is to allow an unlimited number.
If you specify this switch with no number after it, the limit is set to zero.
Triangle always adds points at segment intersections, even if it needs to use more points than the limit you set. When Triangle inserts segments by splitting (-s), it always adds enough points to ensure that all the segments of the PSLG are recovered, ignoring the limit if necessary.
When the -S and -D switches are used together, be forewarned that the -S switch may result in a conforming triangulation that is not truly Delaunay, because Triangle may be forced to stop adding points when the mesh is in a state where a segment is non-Delaunay and needs to be split. If so, Triangle will print a warning.