View Full Version : Stacking objects/rigid body dynamics

07-07-2003, 11:13 PM
I have several projects where I need to have multiple (hundreds) instances of an object that stack up on itself in a physically realistic way and conform to the sides of a container. i.e., a tub of popcorn or a bowl of cheerios. I would like to do this without buying a plug-in, if possible.

I tried several strategies, and none of them worked.

Brilliant Strategy #1:
Use Point Clone Plus

This works for creating many copies of the object, but the copies overlap and intersect each other, and do not respect the boundaries of the container.

B.S. #2:
Use a particle generator with collision and FX Linker to copy the objects to the particles

This creates the copies of the objects, but they still intersect each other. I tried applying Collision to the object in the item properties and Motion in the Motion Options, but this causes the objects to move away from each other, and not stack like they're supposed to.

Dan Ablan uses a similar technique in his book to create a bunch of blowing leaves, but he doesn't say anything about the objects bumping in to each other.

B.S. #3
Use Motion Designer, and fiddle with the settings to make the objects rigid.

This was a complete disaster. I set the bowl as the collision item, and the cheerios as the targets, but they either bounce out of the bowl, or get smooshy and dissolve into the bowl. This is also very slow, considering that you have to re-run the calculation every time you tweak a setting. Then it is frustrating when I've spent a bunch of time, and gotten nowhere.

B.S. #4
Give Up and get a plug-in

I wanted to try this out before I plunked down cash, so I downloaded the Impact 3 demo from Dynamic Realities, but the demo has several features disabled. Therefore, when I tried to do the tutorials, most of the projects didn't work because of the disabled features. So I couldn't really tell if Impact was worth the price.

So, now, I leave it to you, the Lightwave gods and geniuses out there, please help me! I have a deadline and I'm running out of hair to pull out! (Although I suppose I could use SasLite to grow some of that back in, but that's a different post)


BTW, I tried searching the forums, and couldn't find anything that quite fit this scenario.

07-08-2003, 12:44 AM
Well, if you're really running out of time getting your bucks and buying Impact! will be the only solution. Since you speak of hundreds of objects and seem to need a really correct simulation I see no other solution. From past experience I remember it being stable and reliable (even though the main interface is a pain as with all DR plugins). Of course it will be helpful if you keep your geometry as simple as possible....