The models that live in this directory were created with the help of "sphere",
which is a very simple C program that also lives here.  Here's how to use it,
once compiled:


sphere:   tiles a sphere with triangles by recursively subdividing each
          face of a unit octahedron, icosahedron or tetrahedron into four
          triangles, and prints the resulting model to "stdout" in one
          of several possible formats.

Usage:    "sphere [-h] [-i|-t] [-S] [-{v|w|y|o|p}] [-a|-A] d_or_t", where
          -h prints this help;
          -i takes a unit icosahedron (instead of a unit octahedron,
             which is the default) as the initial geometry;
          -t takes a unit tetrahedron as the initial geometry;
          -S tiles the sphere with Sierpinski gaskets (instead of using
             whole triangles);
          -v prints the resulting model in VRML 1.0 ASCII format;
          -w prints the resulting model in VRML 2.0 ASCII format (this is
             the default);
          -y prints the resulting model in YAODL(6D) ASCII format (for
             SGI machines);
          -o prints the resulting model in Open Inventor(1) ASCII format;
          -p prints the resulting model in a private (and completely
             useless) ASCII format;
          -a uses an adaptive (as opposed to systematic, which is the
             default) strategy in the subdivision process, which may
             cause the resulting surface to have "cracks";
          -A is the same as -a, but solves the "cracking problem";
          d_or_t is either the degree of the systematic or the tolerance
             of the adaptive subdivision process that each face of the
             original unit whateverahedron will undergo.

Examples: ("powerflip" and "ivview" are found on SGI machines)
          "sphere 4 > sphere.wrl";
          "sphere -y -a .04 | /usr/demos/bin/powerflip -";
          "sphere -y -A .04 | /usr/demos/bin/powerflip -";
          "sphere -y -i 4 | /usr/demos/bin/powerflip -";
          "sphere -o -S 5 | ivview [-]".