NAME

       gvcolor - flow colors through a ranked digraph

SYNOPSIS

       gvcolor [ files ]

USAGE

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

DESCRIPTION

       gvcolor (previously known as colorize) 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 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                                GVCOLOR(1)