TRIMODEL - make a triangulated sloth (1/velocity^2) model

trimodel >modelfile [optional parameters]

Optional Parameters:
xmin=0.0 minimum horizontal coordinate (x)
xmax=1.0 maximum horizontal coordinate (x)
zmin=0.0 minimum vertical coordinate (z)
zmax=1.0 maximum vertical coordinate (z)
xedge= x coordinates of an edge
zedge= z coordinates of an edge
sedge= sloth along an edge
kedge= array of indices used to identify edges
normray 0:do not generate parameters 1: does it
normface specify which interface to shoot rays
nrays number of locations to shoot rays
sfill= x, z, x0, z0, s00, dsdx, dsdz to fill a region
densfill= x, z, dens to fill a region
qfill= x, z, Q-factor to fill a region
maxangle=5.0 maximum angle (deg) between adjacent edge segments

Notes:
More than set of xedge, zedge, and sedge parameters may be
specified, but the numbers of these parameters must be equal.

Within each set, vertices will be connected by fixed edges.

Edge indices in the k array are used to identify edges
specified by the x and z parameters. The first k index
corresponds to the first set of x and z parameters, the
second k index corresponds to the second set, and so on.

After all vertices and their corresponding sloth values have
been inserted into the model, the optional sfill parameters
are used to fill closed regions bounded by fixed edges.
Let (x,z) denote any point inside a closed region. Sloth inside
this region is determined by s(x,z) = s00+(x-x0)*dsdx+(z-z0)*dsdz.
The (x,z) component of the sfill parameter is used to identify a
closed region.




AUTHOR: Dave Hale, Colorado School of Mines, 02/12/91
MODIFIED: Andreas Rueger, Colorado School of Mines, 01/18/93
Fill regions with attenuation Q-factors and density values.
MODIFIED: Craig Artley, Colorado School of Mines, 03/27/94
Corrected bug in computing s00 in makeSlothForTri() function.
MODIFIED: Boyi Ou, Colorado School of Mines, 4/14/95
Make code to generate interface parameters for shooting rays
from specified interface

NOTE:
When you use normface to specify interface, the number of interface might
not be the number of interface in the picture, for example, you build a one
interface model, this interface is very long, so in the shell, you use three
part of xedge,zedge,sedge to make this interface, so when you use normface to
specify interface, this interface is just part of whole interface. If you
want see the normal rays from entire interface, you need to maek normal ray
picture few times, and merge them together.