ALright, im going to ask here instead of game programming since i will sound like a total n00b. All of the particle systems i had in my last game were VERY basic. Snow would fall, noting would affect it but collisions. Same with rain effects. Now i want something a bit more advanced. Lets say i wanted to have a system where, if a ball flies though the air, it could affect the direction of the snow around it depending on its speed and tradgectory, so that the snow would fly around it instead of into it and vanishing. How could this be accomplished?

I don''t know very much about particle systems, I''ve never actually made one and put into a game, but maybe I can help. You could just display the particles after you display the ball, and that would probably look fine. If you actually wanted your snow to be blown and change it''s vector when the ball passes it, you could always just do some collision detection against the ball. Like, if the ball has radius 50, check collision with the ball''s center but with radius 60, so the particles get effected before the ball hits them, then just add the ball''s vector to the particle vector, or maybe slightly randomly change the ball''s vector that it adds so the new vector won''t be predictable. The only problem is that you''d be checking for collision against against every single particle with every single ball, and if you have 20 balls and 9000 particles that might be a little slow. But I might not have any idea what I''m talking about since I''ve never actually put a particle system in a game, I''ve just played around with them before.


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To have REALISTICALLY swirling snow, you need to look at the Navier-Stokes equations, which are fairly complex and in all likelihood far too complex for your purposes. A simpler solution would simply treat the ball as a repulsive force on the surrounding particles, and have that force be inversely proportional to the square of the distance between the ball and the particle. You might try posting on the Math and Physics forum for more ideas, or you could just try experimenting with a few other methods on your own.

would it be possible to make it so that the front of the object deflects the particles, and then an object, invisible to the naked eye in the back could pull particles towards it at a certain rate, if with a certain radius?

It would take some doing mathwise, but could it be technologically?

Yes.