Re: A couple of RBD questions

["peter boeykens" <peter_b(at)skynet.be>]

Im pretty sure I've done just this, replacing simulated RBD's with nulls, getting the animation as transforms to the nulls, and then parenting the highres geometry under the nulls, and it was on a few thousand, without any scripting and it didnt take all that long.

I'd recommend trying a scene with just 2 or 3 objects to try out what is the right order of doing things. I remember it being a bit quirky, and needing a few attempts to get it working.

 

I think you have to go to the beginning of your simulation, turn caching on and then run the simulation.

when you're at the end you can scroll through the timeline at will, proving that it does pick up the caches allright. Once you have those you can plot the transforms, and from there its whatever way suits you to get those fcurves onto the objects you want.

I dont recall if I constrained nulls to the rbd's and plotted those, or if I plotted the rbds themselves and copied fcurves across. But I think but worked, once you have the caches, and no sooner.

 

 

----- Original Message -----

From: Morten Bartholdy

To: XSI(at)Softimage.COM

Sent: Tuesday, June 26, 2007 3:05 PM

Subject: A couple of RBD questions

I am breaking a wall with RBD and am using a set of pieces which are slightly smaller then the ones I want to render so I can avoid interpenetration in the beginnnig of the simulation. Now I know I can transfer the cache to a clip in the mixer, but if I want to copy this motion to each renderpiece or constrain these to the RBD'ed pieces it starts looking a bit complicated. If I create a cluster with center my RBD is shot. Next thing I would try is to multi point constrain my renderpiece to the RBD piece but this requires me to create three clusters on each RBD piece and then three point constrain each renderpiece to those. Please tell me Softimage thought of easier ways to handle something like this with up towards 100 separate RBD pieces???

 

Another thing is my pieces tend to explode a bit away from each other even though I have made absolutely sure there are no interpenetrations at the bewginning of the sim. I have increased simulation and collision acuracy to very high levels without quite getting rid of this behaviour. Also I have elasticity all the way down to 0.001 since these are supposed to look like concrete pieces, but I still get weird styrofoam like bounce and sploinng-like fly away behaviour from the odd piece when it collides with something again after landing on the ground. I have tried messing with friction parameters without much luck.

 

I am guessing there a tips and tricks I still need to learn about the wonderful world of RBD'ing so if someone knows a way to dampen simulation collisions I would be happy to hear them, if someone in the know cares to share some insight.

 

Thanks!

 

Morten Bartholdy
3D & VFX Artist