NAME

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

SYNOPSIS

       gvcolor [ files ]

USAGE

             <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
       colors 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
       necessarily  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 gvcolorfP 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                      GVCOLOR(1)