POLYMERGE(1gv)															    POLYMERGE(1gv)

NAME

       polymerge - merge coincident vertices, collinear edges, coplanar faces in an OOGL OFF object

SYNOPSIS

       polymerge [-v vertex_thresh] [-e edge_thresh] [-f face_thresh] [-V] [-E] [-F] [-d] [-b] [inputfile.off]

DESCRIPTION

       Polymerge  eliminates  redundancies  from  polyhedral  objects  in OOGL's OFF format, and writes another OFF object to its standard output.
       (Optionally it can produce instead an input file for Brakke's Evolver.)	Specifically,  it  combines  nearly-coincident	vertices,  nearly-
       collinear  edges,  and  nearly-coplanar	faces.	Vertices which aren't used on any face are deleted, as are faces with less than three ver-
       tices.  Thresholds for approximate equality are adjustable from the command line.  Options are:

       -v vertex_thresh
	      Merge vertices when they're closer than vertex_thresh apart; the default is .00001.

       -V     Don't attempt to merge vertices.

       -e edge_thresh
	      Merge edges where |sin(vertex_angle)| < edge_thresh; the default is When edges are merged, the corresponding vertex is removed.

       -E     Don't attempt to merge edges.  (4OFF edges are never merged.)

       -f face_thresh
	      Merge faces sharing an edge where the faces are nearly coplanar: when |sin(angle_between_face_normal_vectors)| <	face_thresh.   The
	      default is .03, or about two degrees.  Note that merging can create faces which are concave polygons.

       -F     Don't attempt to merge faces. (4OFF faces are never merged.)

       -b     Produce an output file in .fe format for Brakke's Surface Evolver, instead of a new OFF file.

       -d     Include  debugging  information  as  comments in the new OFF object.  The comments indicate which vertices and faces in the original
	      object correspond to which in the new one.  Messages include:

       # Vtx nnn->mmm
	      Merged vertices nnn and mmm (both indices in the original object).

       # Merged face nnn into mmm (vertices vvv www) n1.n2 s
	      Faces nnn and mmm in the original object were merged; their common edge joined original vertices vvv and www.   The  cosine  of  the
	      angle between the face normals was s.

       vertex coordinates  # newvertno [order] # oldvertno
	      Each vertex written appears with its new index, its order (number of edges touching that vertex), and its old index (index of a cor-
	      responding vertex in the original object).

       face description  # oldvertno ...
	      For each new face, with N vertices after reduction, the comment indicates N corresponding vertices in the original object.

AUTHOR

       Stuart Levy, Geometry Center, University of Minnesota

SEE ALSO

       anytooff(1), offconsol(1)

BUGS

       Coplanar faces are merged even if they were assigned different colors.  Should be able to handle binary OFF objects, but this  hasn't  been
       tested.

Geometry Center 						   25 July 1993 						    POLYMERGE(1gv)