(09-08-2025, 07:08 PM)d4rk3lf Wrote: Yeah.. it's the old PhysX issue... everything behaves just like glass (too explosive, too much sliding, not feeling heavy at all).
Very noticeable when you're trying to do ground destruction, for example.

I don't know what the solutions will be in your final tutorial, but here is some of the ways I "fight" with it.

1) The most easy approach would be to just make everything BIG.
Same fractured Box will behave totally different if Box size is 50-50cm, or 5000x5000 cm... the 5000x5000 cm would act much slower, and imho.. way cooler ('cos it feels big), and the chunk will not go crazy.
But this solution is not so good if you need to use fluid sims as well (because fluid sims should work best in real scale).

2) Reduce gravity. It can help a lot. In your example that you shown in the video, I think it's obviously that the global scene scale is pretty small (well, it's lego after all), but I think if you reduce default PhysX gravity to 0,5, half of the issues will go away.

3) Reduce 3 parameters in PhysX shape operator under velocity limits. The default is 10k... I reduce it often to 1k, or even less.

4) Reduce size of convex hull. Do you really need 1? Why not 0,9? Will everyone notice very small intersections between fast moving particles?

5) Increase 2 parameters in damping. But be very careful with this. The defaults are like 0,01... so increase really slightly... because this can really crazy slow your PhysX particles (this is like slow operator on steroids)

6) While talking about Slow operator. Yes. Put a slow operator bellow PhysX Shape and in many cases can help a lot. I sometimes just reduce slow on the Z (because I don't want my gravity too much influenced (and I probably earlier reduced my gravity from default anyway, lol).

7) Tyson mentioned in some of the (old) thread that increasing PhysX  substeps can help fighting jittering too... but I try to avoid it until I try some of the stuff above, so I don't slow my sim time.

Believe me, all above mentioned was like years and years of fighting that stupid PhysX behavior, and i really hope that some of the stuff can help you in your projects, and very awesome tutorials you make.


P.S.
I just rewached your video again, and I noticed you mention that you're having issue separating them (even without binds).
Well... I don't know if you are aware.. at some point, Tyson integrated "sticky penetrations" in TyFlow PhysX... and they are default now (they are at the very bottom of PhysX Shape option).
These are not binds - per se - but more like a some hidden small force trying to hold particles together, so they don't explode right away (I think Tyson made them default so new users are not frustrated trying to fight PhysX explosions, while doing simple sims).
So if you want to change that "sticky", just change it to "process all penetrations".

I hope some of this helps.

Cheers.