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Help  Setting the minimum weight needed to make a rope stretch

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Help  Setting the minimum weight needed to make a rope stretch
Cheo13 Offline
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#1
20-07-2020, 04:06 PM
Hello, I'm currently trying to reproduce the hanged men physics from The Witcher 3 with Obi Rope, and my main issue right now is the stretching of my ropes caused by the weight of rigidbodies attached to them. Is there some sort of strength parameter preventing the rope from being stretched by a dynamic attachment until its mass reaches a threshold ? For example, in the Chains sample scene, is it possible to let the chains start stretching only if the ball's rigidbody mass reaches 100 ?
If there is such a parameter, I assure you I will finish recreating The Witcher's rope physics and share the result ! Any way, I hope you can help me and I wish a good day !
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josemendez Offline
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#2
27-07-2020, 08:17 AM (This post was last modified: 27-07-2020, 08:18 AM by josemendez.)
(20-07-2020, 04:06 PM)Cheo13 Wrote: Hello, I'm currently trying to reproduce the hanged men physics from The Witcher 3 with Obi Rope, and my main issue right now is the stretching of my ropes caused by the weight of rigidbodies attached to them. Is there some sort of strength parameter preventing the rope from being stretched by a dynamic attachment until its mass reaches a threshold ? For example, in the Chains sample scene, is it possible to let the chains start stretching only if the ball's rigidbody mass reaches 100 ?
If there is such a parameter, I assure you I will finish recreating The Witcher's rope physics and share the result ! Any way, I hope you can help me and I wish a good day !

Hi,

This isn't possible to do in the general case, as rope stretching not only depends on the weight attached to it, but also on the simulation quality.

You could crank up the amount of substeps high enough that the maximum weight you can attach does not cause any stretching, and then manually set the rope's stretching compliance once the weight is over a threshold. However this requires you to know in advance the maximum weight that can be used.

Check this manual page for an in-depth explanation of how the engine works, and how stretching/substeps/iterations are related. Note that this information is valid not only for Obi, but for all position-based physics engines:
http://obi.virtualmethodstudio.com/tutor...gence.html
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