


GVCOLOR(1)                                             GVCOLOR(1)


NAME
       gvcolor - flow colors through a ranked digraph
       ( previously known as colorize )

SYNOPSIS
       gvcolor [ files ]

USAGE
       dot file.dot | gvcolor | dot -T<format>

DESCRIPTION
       gvcolor  is  a  filter  that sets node colors from initial seed values.
       Colors flow along edges from tail to head, and  are  averaged  (as  HSB
       vectors)  at nodes.  The graph must already have been processed by dot.
       Appropriate choice of initial colors yields drawings in which node col-
       ors  help  to  emphasize logical relationships between nodes, even when
       they are spread far apart in the layout.

       Initial colors must be set externally, using the color attribute  of  a
       node.   It  is  often effective to assign colors to a few key source or
       sink nodes, manually setting their colors by editing  the  graph  file.
       Color  names  are  as  in dot(1): symbolic names or RGB triples.  It is
       best to choose some easily-distinguished but related colors; not neces-
       sarily  spaced evenly around the color wheel.  For example, blue_green,
       green, and light_yellow looks better than red, green, blue.

       Certain graph attributes  control  the  gvcolor  algorithm.   flow=back
       reverses  the flow of colors from heads to tails.  saturation=.1,.9 (or
       any two numbers between 0 and 1) adjusts the color saturation  linearly
       from  least  to greatest rank.  If Defcolor is set, this color value is
       applied to any node not otherwise colored.

EXIT STATUS
       The following exit values are returned:

       0   Successful completion.

       1   If nodes of the graph do not possess a ``pos'' attribute.

BUGS
       It would be nice to make the program work without relying on an initial
       pass through dot.

AUTHORS
       Stephen C. North <north@research.att.com>
       Emden R. Gansner <erg@research.att.com>

SEE ALSO
       gc(1), dot(1), gvpr(1), ccomps(1), sccmap(1), tred(1), libgraph(3)








                          21 March 2001                         1


