I know it’s in preview, so I was having a good look at DOTs physics before maybe using it for an upcoming game.
As a basic test I made a stack of cubes and I was unpleasantly surprised to find that Unity Physics doesn’t seem to be able to stably simulate a stack of 4 cubes without it falling over.
It’s entirely possible that I’ve made some sort of mistake in the setup so I thought I should check in here.
I’ve got one stack of regular monobehaviour physics cubes:
when I press play in the editor the legacy physics cubes land in a stable stack, both stacks of DOTs physics cubes initially land stable-ish, then they slide about and fall over:
I’ve attached the unity project in case it helps get to the bottom of it.
I was also wondering if this was a known issue, as I recall reading in the docs that the new Unity Physics system is stateless, and I know that lots of objects in static contact is actually a tricky problem which physics engines I’ve used before use cached contacts to help deal with.
In general, Unity Physics is not the best choice if you want stable stacking. It is a stateless Physics engine. If you want stable stacking and you want DOTS, you need either Havok or roll your own calculations.
I can appreciate that the stateless approach essentially precludes stable stacking but it’s pretty much a base level requirement from a physics engine for a game right?
TBF this is really a pretty poor situation - as a pro user this means I will have to pay an additional cost for a 3rd party physics solution in order to be able to use DOTS physics to make a game with “standard physics behaviour” :-/
