jit.phys.world global simulation time step / speed change

Diemo Schwarz's icon

Hi, I'm new to jit physics and managed a first mass–spring model, but would like to change the speed of the movements dynamically (but keep the same frame rate). I tried fixedtimestep, but this is not changing the simulation time step.

Note that I'm running jit.phys.world from a metro, because I don't need any rendering, just the physics. Slowing the metro slows the movement, of course, but makes it choppy.

Anything that I missed?

Diemo Schwarz's icon

Alternatively, I'd like to know which parameters to tweak to make the simulation go slower. I tried mass but it didn't do anything, against intuition. An additional problem is that the implementation of jit.physics (from the bullet library) is very generic, using "6dof constraints" and such , so all the known terms from mass–spring models are somehow obfuscated.

👽!t W∆s ∆lienz!👽's icon

try the 'fixed_delta' attribute, send small values like '0.002' to slow it down, (the 'fixedtimestep' seems to set resolution for 'fixed_delta'), does this do what you need?

(the jit.phys stuff is confusing to me, overall, but then again, i didn't even know about the 'bullet library' terms til you mentioned it.)