Provided by: xscreensaver-data-extra_5.08-0ubuntu3_i386 bug


        substrate - Grow crystal-like lines on a computational substrate


        substrate  [-display  host:display.screen]  [-foreground color] [-back-
        ground  color]  [-wireframe]  [-max-cycles  cyclecount]  [-growth-delay
        delayms]     [-initial-cracks    numinitial]    [-max-cracks    nummax]
        [-sand-grains numgrains] [-circle-percent circlepercent] [-fps]


        Lines like crystals grow on a computational substrate.  A  simple  per-
        pendicular growth rule creates intricate city-like structures.  Option-
        ally, cracks may also be circular, producing a cityscape more  familiar
        to places for which city planning is a distant, theoretical concern.
        Ported from the code by j.tarbell at


        substrate accepts the following options:
        -wireframe (Default: False)
                Don't  draw  sand-painting  colored  effects, only make a wire-
        -max-cycles cyclecount (Default: 10000)
                Maximum number of growth cycles before restarting.  The  higher
                this is, the more complex the art.
        -growth-delay delayms (Default: 18000)
                Delay  in  ms  between  growth cycles.  More delay, slower (but
                smoother and less CPU intensive) art.
        -initial-cracks numinitial (Default: 3)
                Initial number of cracks in the substrate
        -max-cracks nummax (Default: 100)
                Maximum number of cracks in the substrate at a single time
        -sand-grains numgrains (Default: 64)
                Number of sand grains dropped  during  coloring.   More  grains
                cause a denser colour but use more cpu power.
        -circle-percent circlepercent (Default: 0)
                The percentage of the cracks will be circular.
        -fps    Display the current frame rate and CPU load.


        DISPLAY to get the default host and display number.
                to  get  the  name of a resource file that overrides the global
                resources stored in the RESOURCE_MANAGER property.
        X(1), xscreensaver(1)


        Copyright  (C)  2003  by  J.   Tarbell   (,
        Ported      to      XScreensaver      2004      by     Mike     Kershaw


        J. Tarbell <>, Jun-03
        Mike Kershaw <>, Oct-04