Substrate(1)                                                      Substrate(1)


       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]


       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: 33)
               The percentage of the cracks will be circular.


       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  ©  2003   by   J.   Tarbell   (,

       Ported  to  XScreensaver  2004  by  Mike  Kershaw  (dragorn@kismetwire-


       J. Tarbell <>, Jun-03

       Mike Kershaw <>, Oct-04

X Version 11                       08-Oct-04                      Substrate(1)

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