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Help  Extreme elasticity on cloth
#1
Hi, i just purchased ObiCloth 4 and i am still learning how to use it. After viewing the sample scenes, I have created a new obi cloth with a custom mesh with a simple setup (curtain like), using a sample cloth (CollisionCloth in ClothRigidBodyInteraction sample scene) as a reference. I have generated the new obi topology from a tie shaped mesh and linked it in the obi cloth component. But while the sample cloth behave really well, my tie cloth present an extreme elasticity (the length of the tie almost double), even with the same parameters in the constrain components as the sample cloth. I tried to tune the distance constraint without success. Also, when enabling the tether constraints the mesh shrink itself no matter how the tether scale is setup. The obi solver is the same for both cloths. Am i doing something wrong? I tried to tune all the constraints parameter for days without any success. In the screenshot attached there is the tie without and with the tethers enabled (tether scale at 1, stiffness at 1).
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#2
(09-09-2019, 10:49 AM)manusense Wrote: Hi, i just purchased ObiCloth 4 and i am still learning how to use it. After viewing the sample scenes, I have created a new obi cloth with a custom mesh with a simple setup (curtain like), using a sample cloth (CollisionCloth in ClothRigidBodyInteraction sample scene) as a reference. I have generated the new obi topology from a tie shaped mesh and linked it in the obi cloth component. But while the sample cloth behave really well, my tie cloth present an extreme elasticity (the length of the tie almost double), even with the same parameters in the constrain components as the sample cloth. I tried to tune the distance constraint without success. Also, when enabling the tether constraints the mesh shrink itself no matter how the tether scale is setup. The obi solver is the same for both cloths. Am i doing something wrong? I tried to tune all the constraints parameter for days without any success. In the screenshot attached there is the tie without and with the tethers enabled (tether scale at 1, stiffness at 1).

Hi,

Your mesh is extremely dense, so it contains lots of constraints. This harms both performance and convergence speed (roughly speaking, convergence == maximum reachable stiffness.)

You could improve convergence by increasing the amount of solver iterations and/or substeps. This will increase the quality of the solve at the expense of performance. Read:
http://obi.virtualmethodstudio.com/tutor...gence.html

Quote:
Quote:Each distance constraint tries to keep two particles at a fixed distance form each other. These are responsible for the elasticity of cloth and ropes. High iteration counts will allow them to reach higher stiffnesses, so your ropes/cloth will be less stretchy.


Ideally, simply use a lower poly mesh. You can also simulate a low-poly mesh and then bind a higher poly one to it using proxies.
Also, keep an eye on your mesh scale. Your pics make me suspect your mesh has scaling issues. Using non-identity scale means you have to compensate for it when creating the topology. Easiest way to get things working properly is simply to ensure your scale is 1,1,1 before you export your meshes to Unity.
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#3
(09-09-2019, 11:38 AM)Ideally, simply use a lower poly mesh. You can also simulate a low-poly mesh and then bind a higher poly one to it using proxies. Wrote: Also, keep an eye on your mesh scale. Your pics make me suspect your mesh has scaling issues. Using non-identity scale means you have to compensate for it when creating the topology. Easiest way to get things working properly is simply to ensure your scale is 1,1,1 before you export your meshes to Unity.

Thanks for the quick reply. I tried to resize my mesh with the same density as the sample one, and indeed now everything works just fine! Also the scale of the old mesh was not 1,1,1 as you suspect. Thank you very much for the help!
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