NAME

     genisopatch - generate isosurface patch

SYNOPSIS

     #include "isotable.h"
     void genisopatch
       (const ISOTABLE::ISOSURFACE_TABLE_POLYHEDRON & polyhedron,
        const long code, vector<int> & edge_list,
        int & num_simplices);

ARGUMENTS

     const ISOTABLE::ISOSURFACE_TABLE_POLYHEDRON & polyhedron
          A convex polyhedron  containing  the  isosurface.   The
          polyhedron  may be in dimension other than three but it
          must be convex for genisopatch to produce a proper iso-
          surface.

     const long code
          Encoding of vertex signs, + or -.  If  bit  i  of  code
          equals  1, then vertex i has positive sign.  Otherwise,
          vertex i has negative sign.

     vector<int> & edge_list
          Array of polyhedron edges  containing  isosurface  ver-
          tices returned by genisopatch. Isosurface simplex j has
          vertices   on   polyhedron    edges    (edge_list[d*i],
          edge_list[d*i+1],  ...,  edge_list[d*i+d-1]) where d is
          the polyhedron dimension.

     int & num_simplices
          Number of isosurface simplices returned by genisopatch.

DESCRIPTION

     Given a convex polyhedron  polyhedron  and  a  sign  pattern
     (+/-)  defined  by code, genisopatch generates an isosurface
     in the polyhedron which separates the positive (+)  vertices
     from  the  negative  (-) ones.  genisopatch returns a set of
     d-dimensional simplices forming the isosurface  where  d  is
     the  dimension  of  the  convex polyhedron.  The vertices of
     each simplex lie on the edges of  the  original  polyhedron.
     The vertices are specified, not by their coordinates, but by
     the  polyhedron  edges  containing   the   vertices.    This
     separates  the  computation  of  vertex coordinates from the
     generation of the isosurface simplices.

NOTES

     The input polyhedron must be convex for genisopatch to  pro-
     duce a proper isosurface.  genisopatch creates an isosurface
     from a subset  of  the  convex  hull  of  a  subset  of  the
     polyhedron  vertices  and  edge midpoints.  It uses a convex
     hull routine written by K. Clarkson.

SEE ALSO

     genisotable,isotable(3).

AUTHOR

     Praveen Bhaniramka, Rephael Wenger