rope vs cloth

[dswigger]

   
I am trying to figure out how to simulate a belt-like material (thin rectangular box) as pointed to by 2 and attached to 1(in screenshot).

I want the belt flexible but stiff(like a harness).  Should I be using rope or cloth?  I own both and am thinking cloth might be better solution.

Thanks for any help.

-David Swigger

[josemendez]

I am trying to figure out how to simulate a belt-like material (thin rectangular box) as pointed to by 2 and attached to 1(in screenshot).

I want the belt flexible but stiff(like a harness).  Should I be using rope or cloth?  I own both and am thinking cloth might be better solution.

Thanks for any help.

-David Swigger

Ropes do not model torsion, which means your belt would be free to rotate around its longitudinal axis. You could use rods instead, which do model torsion. But either ropes or rods would approximate the belt as a cylinder, which for collision detection is not really accurate.

I'd use cloth for this. Make sure to use enough substeps to reach the desired stiffness, then increase bending compliance (or deactivate bend constraints entirely) so that it is flexible enough.

[dswigger]

Ropes do not model torsion, which means your belt would be free to rotate around its longitudinal axis. You could use rods instead, which do model torsion. But either ropes or rods would approximate the belt as a cylinder, which for collision detection is not really accurate.

I'd use cloth for this. Make sure to use enough substeps to reach the desired stiffness, then increase bending compliance (or deactivate bend constraints entirely) so that it is flexible enough.

Thanks!  I played around with ropes and observed exactly as you stated.  Next steps are playing with cloth to figure out how to do what I want.  When you say substeps - can you elaborate?

[josemendez]

Thanks!  I played around with ropes and observed exactly as you stated.  Next steps are playing with cloth to figure out how to do what I want.  When you say substeps - can you elaborate?

Substeps are the main "quality vs performance" setting in Obi. You can find this in ObiFixedUpdater component. More substeps chop Unity's timestep into smaller... well, sub-steps. This increases simulation quality, allowing the solver to reach higher effective stiffnesses. Less substeps cause the simulation to be updated less often, yielding worse quality (overall unwanted stretchiness).

The manual has an in-depth explanation of how both substeps and iterations affect the simulation:
http://obi.virtualmethodstudio.com/manua...gence.html