06-27-2023, 07:19 PM
I guess my first question would be - does the belt even need to be dynamic? Unless you're simulating it breaking or something, I don't see why it would need to be a simulation at all, instead of a simpler path deform or something like that...
As for the stretching...you can increase PhysX solver values (pos. iterations corresponds directly to bind stability) yes, but if you stretch a network of binds beyond their physical limit you will never get stability because it'll basically be in an impossible configuration (from your screenshot it looks like you're stretching the belt, even if only a little bit).
In other words, if you take a chain of unstretchable binds that is 10 units in circumference, and put it in a scenario where its stretched to 11 units in circumference, you will always get weird stability issues because it's not a physically possible configuration (in reality an unstretchable system like that would simply break).
Now - the key word there is 'unstretchable'. With PhysX joint binds, if you do not enable movement spring, the binds will be treated as physically unstretchable - they can bend but will not be able to stably stretch. If, however, you do enable movement spring, then stretching them will no longer necessitate jittery instabilities. In a situation where you want them to be virtually unstretchable with maybe a little bit of give-and-take, you can enable movement spring but give it an extremely high values (say, 1 million)...that will allow the solver to treat the system more stably as a whole, without the binds being given too much leeway to spread apart. Essentially you'd be simulating a chain of material like thick rubber, rather than what you're doing now which is more like a bicycle chain (that would become unstable and break if stretched beyond its rest length).
Attached is a file for you to examine. Turn movement spring on/off in the PhysX Bind operator to see the difference....disabled it explodes, enabled it's smooth as butter.
As for the stretching...you can increase PhysX solver values (pos. iterations corresponds directly to bind stability) yes, but if you stretch a network of binds beyond their physical limit you will never get stability because it'll basically be in an impossible configuration (from your screenshot it looks like you're stretching the belt, even if only a little bit).
In other words, if you take a chain of unstretchable binds that is 10 units in circumference, and put it in a scenario where its stretched to 11 units in circumference, you will always get weird stability issues because it's not a physically possible configuration (in reality an unstretchable system like that would simply break).
Now - the key word there is 'unstretchable'. With PhysX joint binds, if you do not enable movement spring, the binds will be treated as physically unstretchable - they can bend but will not be able to stably stretch. If, however, you do enable movement spring, then stretching them will no longer necessitate jittery instabilities. In a situation where you want them to be virtually unstretchable with maybe a little bit of give-and-take, you can enable movement spring but give it an extremely high values (say, 1 million)...that will allow the solver to treat the system more stably as a whole, without the binds being given too much leeway to spread apart. Essentially you'd be simulating a chain of material like thick rubber, rather than what you're doing now which is more like a bicycle chain (that would become unstable and break if stretched beyond its rest length).
Attached is a file for you to examine. Turn movement spring on/off in the PhysX Bind operator to see the difference....disabled it explodes, enabled it's smooth as butter.