View Full Version : Dynamic Pile

01-14-2011, 09:53 AM

I'm trying to use dynamics to pile up rubble in believable piles like william shows in his cereal bowl video but have a couple of problems.

Having created a floor object as the collision surface and applied hard dynamics to the rocks etc the rocks dont interact with each other using the rock surface as the collision node.

I tried slightly inset spheres as a compromise but all the objects slide across each other until they are all level and dont stick with the jagged surfaces of the rock - I guess because the collision is now a sphere - so is this idea beyond lightwave? or am I missing something?

Thanks for any pointers


01-14-2011, 11:44 AM
after a bit more questing - I suppose I'm asking if its possible to get dynamics to sort out the collisions for irregular shapes using the actual surface shape rather than a box or a sphere

01-14-2011, 12:26 PM
I also did the cereal tutorial some time ago. I then used the hardFX for a similar project-- not using rocks, but rather diamonds piling up in a treasure chest. I did end up using the spherical setting, as my diamonds didn't have enough vertexes to really "collide" well. I was able to get them to pile up using spheres, but I did have a container around them.

I seem to remember that using the actual surface requires a lot of points, and a Sub D object would be best. Then you can bump up the sub patch level and calculate the FX with the Sub D order set to first. This was taking too long to compute the motion in my project, so I set it to spheres instead.

It's been a while, but I'm thinking if you set the bounce property really low, that should help the rocks to pile up rather than bouncing away from each other. Also could you us an invisible container to keep them from spreading out flat?

Also I can't remember if there is a friction setting in HardFX or if that is only cloth and particles. If there is that should also help them to be "stickier".

If you have a simplified test scene, maybe we can help with the settings.

You can see the usage I mentioned here:


The diamonds piling up are at the end. Since they are in a box the bounce setting was pretty high so they do bounce and roll around a bit. Without the box they may have spread out too much.

01-14-2011, 02:50 PM
thanks thats useful info will give it a whirl and I'll upload a test scene too - Thanks

01-14-2011, 02:56 PM
here are the files