	@(#)TRIANGLE.HOWTO	1.3  03/12/99

GMT contains two programs (triangulate and pscontour) that
directly or indirectly will do a Delauney optimal triangulation
of arbitrarily spaced (x,y,z) data.  In the old days, GMT used
a public domain (published) algorithm by Dave Watson [1982] to
to this.  Now, a new and much faster algorithm has been released
by Jonathan Shewchuck [1996] and it is the default triangulation
routine in GMT.  Because Shewchuck holds the copyright you are
advised to read it (in README.TRIANGLE) to see if you agree with
it.  Basically, if you work for a for-profit company you may need
to check to see if you will need a license.  The install_gmt
script asks you what you want and changes the scripts accordingly.
If you later need to change the behavior w.r.t. triangulation,
follow these guidelines:

In makegmt.macro there are two parameters that can be defined:
TRIANGLE_D and TRIANGLE_O.  By default they are defined.
To revert to the old GMT usage of Watson's [1982] algorithm,
simply place a # in the first column at these two lines.
Then, say 'make clean' and 'make install' again.
Likewise, to use Shewchuck's [1996] routine, remove the # from
the beginning of the lines and then 'make clean' and 'make install'.

Paul Wessel, 13-MAR-1999


	REFERENCES

Watson, D. F., 1982, Acord: Automatic contouring of raw data,
   Comp. & Geosci., 8, 97-101.
Shewchuck, J. R., 1996, Triangle: Engineering a 2D Quality Mesh Generator
and Delaunay Triangulator, First Workshop on Applied Computational Geometry
(Philadelphia, PA), 124-133, ACM, May 1996.
[www.cs.cmu.edu/~quake/triangle.html]
