Article 8412: : Fun with Particles

We all have seen Particle Systems. They lie under those smoke and fire effects we often see in games or movies. A Particle System is controlling the motion of a collection of objects following some rules. It can be two- or three-dimensional, and in rare cases higher dimensional (or even one-dimensional). In this article, I'll focus on how to make your own effective 2D Particle System. The objects are circles and the rules are elastic collisions with a boundary and elastic collisions with each other. I don't show how to put render effects onto those particles or how to generate CGI-effects. Instead I will concentrate on how to make an effective particle-particle collision so that you can move a high number of particles without having to compute too much. Once you have the system, you can implement your own rules of particle-particle interaction, design your own physics, or use it to produce effects within a game. I've made models for the simulation of chemical reactions within a cell, the simulation of thermal-transport, or a visualization of thermodynamic effects. A particle system for a scientist is a little bit like farina: you can make a lot of different breads and cakes out of it! Have fun with playing around.

Years ago I read about algorithms that make an effective collision detection with multiple objects. It was interesting, but I didn't find the time to play around with it. But within the last few months I needed to program some interesting simulations based on particles that interact. (This was the visualization of some chemical reaction dynamics in a cell, with the influence of enzymes.) For that problem I needed effective collision detection and I thought I would share what I learned about it. I originally worked in a language called Processing (see the "Processing" sidebar), but for REALbasic Developer, I ported the project's kernel to REALbasic so you can play around with the running program and make your own experiments.

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Fun with Particles

Particle systems are fun!