Using stochastic processes to generate paint type effects in processing.org

by jaymz on 15/06/2010
I very much like to play with processing.org when I’ve got some downtime. I’ve wrote a small particle engine a while back in the framework and this time I thought I’d try and do something a little more arty from the outset. My inspiration for this “sketch” was the many splatter paintings by Jackson Pollock. I can remember going to see some of his work at the Tate modern in London quite a long time ago. I had always thought it a bit poor as “art” when I was a kid but later on I developed an appreciation for the format. If you have no idea what I’m talking about, this is an example:
Now my sketches don’t look much like this but I did capture some of that splattering chaotic effect that I wanted. The basic process is very simple, a class called a Walker will randomly make its way across the canvas. As it moves the vector distance of each step is calculated. If the step is big enough it causes a burst of circles to be drawn, each with a slightly random position & varied alpha to give it some texture. To avoid it becoming a little too busy I’ve limited it to a set palette at runtime which can be regenerated as walkers are added.

I was quite happy with the random scatter effect as different pools of colour made their way through the canvas space. I thought it would be a nice addition to add in some basic boundary conditions so I added a quick polygon class and added in an array of those. A few functions later and I could click around the screen defining new polygons. Using the well known Jordan Curve theorem we can tell if the walker is currently within an arbitrary polygon (without holes of course). Here’s an example video of it in action. Heart’s seem pretty easy to draw compared to anything crazy complex and give a good idea of the effect:

I’ve added quite a few options to the code now allowing me to switch on & off the boundaries as well as add an arbitrary number of polygons. If the vertices overlap then the way the “point in polygon” algorithm works it will flag each “contained” area as a solid.
Finally here is a nicely captured heart shape. It gives a nice idea of the kind of effect when combined with a boundary. I think playing around with the way the walkers are coded could be fun, for example doing a neighbour check and tweaking the randomised movement accordingly could create a weak flocking style system with Brownian motion driving it.
If you’re interested in checking the code out you can find it over on github. It should run for you ok out of the box within your processing environment.
jaymzcd@googlemail.com

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