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Q Paul

Ropes pulling softbody through a hole

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I am trying to pull an organic tube (gray) around by its end through some colliders(purple) and up through a hole in an object using two ropes that are attached to it (blue). The rope needs to be pulled through the hole not initially by the end but with a loop or torus (yellow) about midway. My initial thought is to setup spline dynamics and constrain the soft body on its end.  Then Hair collider or dynamics collider on the object with the hole.   Collider body on the torus.

Once the rope is through, I want to pull the soft body up into the hole by pulling on the end of the ropes instead of by the torus that pulled it through the hole.


WIll the soft body respect the same collision as the spline dynamics or only collision from the simulation dynamics? 

Right now my rope is not properly colliding with the Hole in object and I cannot drag the soft body along with the rope as I have not figured out how to constrain the hair to a selected point or polygon on the soft body. Still searching ... 

Lastly I would like the rope to slip through the torus as it is pulled rather than the way I am doing it now which is to constrain it to the torus and pull.

Below is a screenshot that lays out the general idea.


I realize there is a lot of questions and information here. Feel free to address any or all parts, I would break it into select tasks, but want to make sure all the other elements would still play nicely.

Thanks in advance.

Happy to upload the sample file if someone wants to have a look.





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This looks tricky!  I think I get what you're after, but I'm not sure full-on simulation of all of this is the best route.  You might be better off trying a combination of the spline dynamics on the ropes with a Spline Wrap deformer on your tube.  I messed with your scene a bit and noticed it's almost impossible to get the ropes to slide along the torus rather than just stretching out the shorter end.  I set the friction to 0 and upped your spline segments, but that didn't seem to do much.

One quick tip- You'll want to use a lower-poly mesh for your tube- you've got a TON of segments around the radius that are slowing you down (if you DO want to simulate it.

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I messed with it some more and made a little progress.  I think the rope going through the hole is working now.  The Spline Wrap works ok, but probably not as realistic/dynamic as you want.  You could set up some more deformers to make it squish a bit when it goes into the tube.

Spline Through Hole v1.c4d

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Attached is a scene file that uses spline dynamics and hair colliders. 

You'll need to play with the collision radius on the Spline Dynamics tag though to get the collisions right. 


Hope this helps.

String Rig 01.c4d


Also see these tutorials by eyedesign, it features some dynamics and softbodies, but it might give you some ideas. 




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Nice work, @southpaw!  I opened your file and got it to be a little smoother, but can't completely get rid of the jumpiness as it slides along the cube collider.

@Q Paul are you there somewhere?

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I've been thinking about this, and I think it might be worth trying to make it with soft bodes and connectors.


Like making a chain of low poly cubes, each with a softbody tag attached,  stuck together with connectors. Then use a mesh deformer on another higher poly object like a rope to mimic the motion of the low poly chain.


Also, I think you can use a linear cloner, add a soft body tag to that, and in the soft body settings, set the drop down to "Made of Clones" or something similar. This adds springs between each clone. But connectors may be the way forward, as you can then pull either end of the chain to control it.  

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I am a real fan of hair and tend to use it for organic stuff every chance I get because it is so versatile.


Here's a technique you could use for pulling the sutures through the hole.




Move the platonic in X to position the sphere on the Hair and use the User Data to move the sphere around. Even if you don't use it, it is fun to play with!

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Here is a better example. Change the Y Add Force from 100 to 200 and watch what happens.


Hair Proximity 3.c4d.zip

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@Teknow, clever stuff, I played with the hair xpresso nodes a while ago, but haven;t tried the Hair proximity or add force port brofre. The hair nodes do give you some useful ways to connect/contrain objects.


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Here's a rough set-up using the dynnamics tags and connector idea I mentioned in an earlier.


Dynamic String-Connectors.c4d

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