How to emit real random particles

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.

• 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? – Bruno Jan 30 '18 at 11:09
• 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 – 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.

• 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 – Crantisz Jan 30 '18 at 12:15
• @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. – cgslav Jan 30 '18 at 12:30
• and also, you can edit this driver without Graph Editor – Crantisz Jan 30 '18 at 12:50
• This helps a lot, but is there a way to work around the disabled auto-run? It make it less automatic. – jspr Jan 30 '18 at 12:59
• @ajwood I've found it in the docs: docs.blender.org/manual/en/dev/animation/drivers/… look for "Expression" paragraph. – cgslav Jan 30 '18 at 13:13