INSIDE -  Is a vertex or point inside a circum circle, etc. of a triangulated
          model

inCircum	determine whether or not a vertex is inside a circum circle
inCircumTri	determine whether or not a vertex is inside a circum circle of
                 a triangle
in3Vertices	determine whether or not a vertex is inside triangle (v1,v2,v3)
inTri		determine whether or not a vertex is inside a triangle 

Function Prototypes:
int inCircum (float x, float y, float xc, float yc, float rs);
int inCircumTri (float x, float y, Tri *t);
int in3Vertices (float x, float y, Vertex *v1, Vertex *v2, Vertex *v3);
int inTri (float x, float y, Tri *t);
inCircum:
Input:
x	x-coordinate of vertex
y	y-coordinate of vertex
xc	x-coordinate of center of circumcircle
yc	y-coordinate of center of circumcircle
rs	radius^2 of circumcircle

Returns:
1	if x,y inside of circumcircle
0	otherwise

Notes:
A vertex exactly on the edge of a circumcircle is taken as being outside

inCircumTri:
Input:
x	x-coordinate of vertex
y	y-coordinate of vertex
t	pointer to Tri

Returns:
1	if x,y inside of circumcircle of a triangle
0	otherwise

Notes:
A vertex exactly on the edge of a circumcircle is taken as being outside

in3Vertices:
Input:
x	x-coordinate of vertex
y	y-coordinate of vertex
v1	pointer to first Vertex
v2	pointer to second Vertex
v3	pointer to third Vertex

Returns:
1	if x,y inside of v1,v2,v3
0	otherwise

Notes:
A vertex exactly on an edge of the triangle is taken as being inside

inTri:
Input:
x	x-coordinate of vertex
y	y-coordinate of vertex
t	pointer to Tri

Returns:
1	if x,y inside a triangle
0	otherwise
Notes:
A vertex exactly on the edge of a triangle is inside

Author:  Dave Hale, Colorado School of Mines, 06/04/91