Restrict simulation to 2 axis?


Hey all. quick question here.

Im doing a hard body sim with some objects falling into a container. Id like to keep the individual objects (the whole some really) restricted to 2 dimensions (motion in Y and Z but no X). Im sure there is a simple way to do this but its eluding me at the moment



Maybe the protection tag could help?


Almost. However with the protection tag, the objects no longer collide correctly, they start to pass through one another

edit actually it looks like the protection tag is just correcting the simulation after the fact. the simulation calculates the positions in all three dimensions then the correction tag pushes everything back to the protected axis.


I wonder if changing the priorities of those two would help with that. If the Protection tag is calculated before the simulation, perhaps your results will be more favorable.

Just spitballin’…


Not much to go on since dynamics react differently on a sphere
or cube. That said, creating some invisible guides … planes or
tubes that funnel the items along “may” help :shrug:


I found if you use the connector object on a single object you can restrict it to motion on a plane and it will apply its constraints as part of the simulation. However once you dump that object into a cloner, it no longer works. bummer there.

Vid2k2, i ended up doing something similar to your guides idea. I used a wind force to push everything against a vertical plane as they fall. its a hack but it ended up working about as i wanted. occasionally an object pops out in front but its a useable workaround.

Id still love to know if this can be done correctly if anyone has a pointer. The connector object is close, if there was a way to get it to work on multiple clones. Ive also tried PSR constraint (set to generators), but again, once dynamics are active the constraint no longer functions


You can use Xpresso to remove the Y component from the velocity and reset the position.
See attached example


Thanks Srek. I’ll have to take look at that when i get a chance.