I'm working on a sort of idea that you can make an unique 'drawing' by downloading this blendfile, run the animation and get a truely unique drawing. Key of the concept is that designing needs no skill or knowledge.

Problem: I created a 'drawing machine' that emits random particles (size and life) and paints the canvas by using dynamic paint. But everytime I play the animation the exact same drawing comes out.

Of course I could use seed, but it will contradict the concept.

The Drawing Machine and canvas

  • $\begingroup$ typically seeds are initialized with a clock based value to garantee a new random set at every runtime. Ex: seed = int( time.time() ). Are you setting any seed at the moment? $\endgroup$
    – Bruno
    Jan 30 '18 at 11:09
  • $\begingroup$ In PC we have "pseudorandom number generator". It's very near to random generator, but it not relay random. In PC very difficult to get "true" random numbers $\endgroup$
    – Crantisz
    Jan 30 '18 at 11:19

You can use Drivers to get "random" Seed in Particles settings.

As @Crantisz pointed you can just paste #int( 99 * noise.random() ) as a Seed value and Driver will be automatically added.

Long way:

  1. Right click on Seed and Add Driver > Manually Create Later (Single).
  2. Go to Graph Editor and switch to Drivers mode.
  3. In Drivers tab paste this expression: int( 99 * noise.random() )
  4. Update Dependencies.

Now every time you open Blender Seed value will be different.


  • 4
    $\begingroup$ I want to note, that you can do same thing just by entering #int( 99 * noise.random() ) as seed value: i.stack.imgur.com/GOKuX.gif $\endgroup$
    – Crantisz
    Jan 30 '18 at 12:15
  • $\begingroup$ @Crantisz nice one! The result is the same but amount of steps is hugely reduced. Is the # symbol shortcut for adding Driver? I wasn't aware of this method. $\endgroup$
    – cgslav
    Jan 30 '18 at 12:30
  • $\begingroup$ and also, you can edit this driver without Graph Editor $\endgroup$
    – Crantisz
    Jan 30 '18 at 12:50
  • 1
    $\begingroup$ This helps a lot, but is there a way to work around the disabled auto-run? It make it less automatic. $\endgroup$
    – jspr
    Jan 30 '18 at 12:59
  • 1
    $\begingroup$ @ajwood I've found it in the docs: docs.blender.org/manual/en/dev/animation/drivers/… look for "Expression" paragraph. $\endgroup$
    – cgslav
    Jan 30 '18 at 13:13

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