Wizzy particles

On my first visit to an open day for my secondary school in Exeter (This was when I was twelve), I was entranced by a demo in the otherwise rather sparse computing department, consisting of a number of brightly coloured particles that chased each other around the screen in a perpectual cascade, apparently suspended around a centre of gravity in space. At the time, I couldn't work out why the particles didn't simply catch up with each other and coalesce; the physical world the particles inhabit is frictionless and defies the laws of thermodynamics, and so there's no surpirse that the motion of the particles is counter intuitive. Nevertheless, there was something incredibly satisfying in watching them race around the screen, and several years later I constructed my own interpretation of what I imagine is a classic computing exercise. This was one of the earlist full programs I constructed using my high-res SVGA graphics library, and it demonstrates its speed wonderfully. Around 200 particles, represented by small (smiley) sprites are created in random positions on the surface, and accelerate towards their assigned forrunner. A gravity source keeps the scrummage centralised on the screen, and by altering the source all the physial factors can be varied, loeading to some interesting and sometimes bizaare effects. In the original program, up to two gravity sources could be introduced and moved with the mouse, but this program predates the development of the SVGA mouse unit, which I had to construct from scratch (finding many of the available ones unsatisfactory), and so this remains a fixed demo, with a few key combinations: space resets the particles to the origin, and S reverses the order of persuer and persued, making the bundle rotate in the opposite direction. This remarkable simple program required a minimal knowledge of newtonian mechanics and an afternoon to put together, and I was rather pleased with the results at the time. Enjoy playing with this demo; it is probably best enjoyed by those that have the capability of doctoring the source code. The demo can be downloaded with full source.

Download the Wizzy particle demo (52 kb, zipped) | Back to Graphical trinkets