I am designing a weather system for my game engine. Along side of development of this engine i will be creating a particle engine and a physics engine. The weather system will use some features of the particle and physics systems(rain and snow[particle] wind and collision responses[physics]). Sky domes with dynamic skies and sounds(daylight, stormy skies). I even want snow and rain to collect on the ground. I could use a little direction for each system any links or current projects would be helpfull.

JUST FAKE IT AND NOBODY WILL KNOW.

GASP! i would know. Im going for realism here.

I'm with BRIAN on this one. Don't waste your time on simulating this, just make it appear fairly realistic and get on with your game instead.

indeed. programmers simulate, coders fake. :)

In my opinion you should use wind along with some turbulence to simulate the rain and snow as a separate system, and point sprites (3dmark 2001 stile) for the raindrops on objects. It looks cool and dosent steem the procesor. Also in my opinion some pshader perlin dynamic clouds would look quite nice if your up to it www.humus.ca has some nice articles also there were some posts of Yan L about parametric generated clouds i implemented miself, (he had also sub surface light scatering)

Hope I helped, but realy simulating 1000 colisions per sec cause of rain drops is futile

Im almost done with the first version of the weather system im starting out with just a snow emitter. The weather system will manage multiple emitters I want to get to the point of having rain and snow running at same time (freak of nature). Also (I know this is pointless and probably a waste of cpu cycles) the snow emmiter, during each generation of new particles will randomly select one of three snow flakes (poor mans nature sim).

Finally got the weather system working. Its a little buggy right now, some particles are slow, some fast. Dont be too harsh on me im just starting the thing. check it out.

picture ---> http://www.geocities.com/maxamfate/weathersystem.JPG
program -----> http://www.geocities.com/maxamfate/blue3d0.04.zip

tell me what you think.

i dont mean to be rude or something, but this is proabebly the worst snow-routine i've ever seen. seriously.

try getting some smoother motions, better visualisation (the particles appear to be drawn in random order with alpha-testing -- dont. sort them back to front. trust me, it'll look WAY better.), and if you have to "steal" particles from the ground, fade them out slowly first instead. (in the simulation you might want to decrease it's size as well, so particles won't all of a sudden dropp down when one particle is resycled)

(tears running down face) I work day and night on my engine this is the first (sob) real(sob) try....

Well I have been working over my little engine and feel this demands a little boost in version so here is the beefy v0.05. From my last demo the snow system has GREATLY improved. Now snow, Multi object multi texture 3ds files(not really new), Frustum culling, Bound Box collision, and poly collision all at once. keep tapping up and down keys to move box.

0.05 Engine in action (pic) ----> http://www.geocities.com/maxamfate/new3de.JPG

here is the exe ----> http://www.geocities.com/maxamfate/Blue3Dv0.05.zip

im gonna fix the kb issue, tell me what you think.

Looks alright, but I think you should be trying to make a general particle effect rather than specific weather effects. If you need something special for rain/snow just derive from your particle class.

Also I don't like your way of adding particles. You seem to add in # per second until you have your max, at which point you reuse dead ones. That takes a while to stabalise. You have some other options: Keep creating particles at a steady rate, and simply kill an old one if you get too many. That's not very intuitive, but and it might be difficult to fade them out. The second is to not bother clamping the number of particles, just give them a creation rate and lifetime and let it waver, but make sure your not allocating and deallocating memory the whole time for them.