Fixing Interpenetration

Hi,

There are a couple of ways to keep interpenetration from happening. I will preface that by noting that most destruction shots happen pretty quick so it is generally not an issue with debris. You can also key a passive region to control movements after a particular shot.

Specifically though, you should understand why interpenetration happens. It is an artifact of the way we currently do contact resolution. Rather than just use force, we also use the rate of interpenetration to determine the pushback force. If something moves slowly, it can keep a sufficient counterforce from being generated. You can resolve this several ways:
1) Increase sub steps - This allows the system to respond more accurately to interpenetrations.
2) Increase Young's Dampening - This adjusts energy dissipation from material flexing
3) Decrease density - This keeps a large force from being generated over a long period of time
4) Increase friction - This keeps stuff from moving, increasing the chance that the system will automatically freeze it.

We have a new contact system in development that will fix these problems (it has perfect contact resolution in fact...) but that system is still being optimized. We hope to have a release in the next 4 months, and perhaps will have beta testing before then. If you are interested in that, please send an email to info@pixelux.com or send me a forum message.

As a demonstration of the points I made, I have attached a scene that shows the effects of material adjustment on interpenetration.

Hopefully this will help.

Cheers,
Vik

File is here:
IPFixes.zip