A particle system should be very simple at the core. - if your system isn't then its alot of processor hit for not much effect... Each particle should be a structure with position, directional vector, speed, life span and gravity.
To create a cascade effect just simply emit particles from point a with a direction that takes them up and give lifespan of x frames and some gravity. Simple ;-)

So in a frame you move each particle according to its direction vector, apply gravity and see if its decayed. This can all obviously be extended but that is basically all you need.

There should be stuff on Flipcode and there is a rather nice 2d program called the Explosion Graphics Generator (EGG) on the PC that has source available that you can look through.

Hope that helps.

What I'll need to do though is in addition to implementing x and y velocity and gravity, to alter this velocity perhaps to take accout of loss of energy in an explosion for example.

I'm thinking of having particles exploding from a point and cascading downwards so I would give the particles a diagonal upwards vector and then reduce the velocity or perhaps just increase gravity to simulate loss of energy.

Alternatively, if the explosion was in space then I could just use circular explosions and include the lifespan element as opposed to dropping off screen.

Andrew

[Edited by andreww at 00:26, 3/5/2001]