PDA

View Full Version : How to make 2 collision test?


pentool
10-06-2007, 02:21 AM
Ok, so I'm creating a snowglobe and getting my feet wet with particle flow for the first time. Besides reading the manual (so so) and watchied the movies on particlefx.com, I am planning to purchase a DVD of some sort about particles. Until then...

In case you don't know what a snowglobe is (just to be on the safe side, image here (http://www.english-heritage.org.uk/upload/img/12_SNOWGLOBE_lo_res.jpg). Not mine, just a photo.)

So what I do is, when the particles are falling, I have an SDeflector that is just a tad smaller then the glass. If the particles hit that, they will bounce back. So far so good. Playing the preview in the viewport is just dandy.

But I also want the particles to disappear when they hit the ground (bottom of the globe). So I added another collision test at the bottom of the event (UDeflector - see attached screenshot) which has the ground attached to it, and that will delete the particles that hits the ground.

Well, it kinda works, but the prollem is that when I do this, and play it back in the viewport, the preview virtually comes to a crawl. I only preview about 100 particles in the viewport, but still.

If I take the ground collision test out, and preview even 1000 particles, it has no affect on the playback. The ground object is a patch, made of splines. Would this be a reason that the preview comes to a crawl, or my event setup has some issues? Such as, I can only have 1 collision test per event or something...?

Thanks!


http://i132.photobucket.com/albums/q32/pentool/particle_1.gif


Is this the way to do 2 collision tests, right after another?

pentool
10-06-2007, 02:42 AM
I guess I've just found out. It was the ground indeed. Seems like the patch surface was too complex (although it's just a little bumpy surface). When I replaced the UDeflector with just a simple deflector plane and used that, the playback speed regained consciousness! Woo-hoo!

PartiallyFrozen
10-15-2007, 05:27 PM
FYI,

The reason that you were getting slow response times are because you were using a patch which has a really high resolution. When Pflow is calculating the collisions it is looking at each vert/face and asking if its touching or not. In the future, if you need to make a colision with an object i always try and create a Low res mesh proxy with an optimize modifier and run the calculations on that. It can speed things up and create the same effect.

Keep on noodling particles are fun!

Mark

CGTalk Moderation
10-15-2007, 05:27 PM
This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.