# Modeling a chain

Hi everyone,
I’m trying to model the behavior of a chain, I want to use the final definition to simulate how a complex necklace stands on the body after creation. I have 3 problems:
first, the chain gets torn after a while.
second, the jewelry-stand moves, cant make it stay solid.
the third problem is that it runs really slow.

I attach the definition with very simplified meshes as input, I will be thankful if you help me through

KANGAROO PHYSICS-4.gh (40.8 KB)

Thank you

Hi.
You might want to avoid solid collision at all.
Here https://vimeo.com/221471947 Daniel probably used [Collider] to just make collision between simple curves, instead of solids.

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KANGAROO PHYSICS-4_V2.gh (46.7 KB)

Note that the actual geometries (meshes) are moved by using [Orient] after the simulation.
During the simulation or “inside kangaroo” (goals etc) you should want to use simplest possible geometries, like points and lines.

Here i made a rectangle exactly in the “soul” center of the chain element thickness.
Then from that rectangle i made its points (corners conceptually, but also more for some bonus quality) collide with an offset-ed mesh of your neck-stand, so the computation is simple, just point to a mesh!

Similar, with the [Collider] i made the rectangles collide each-other, but again those are simple lines geometries. (Big thanks for the collider component anyway!)

Lastly, at the kangaroo output, you pick just the oriented frames and relocate an actual mesh.

The result is not completely correct because the collisions behave like the geometries are circle/pipes/spheres (just distance-based) … but the whole process is much faster than a true solid body collision.

If you would use another software (like blender?) this amount of solid mesh collisions wouldn’t be a problem at all… but it’s difficult to leave the rhino environment (i’m just lazy to try it…)

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I have a new problem, when I load your definition it asks for 2.5.2 version of some components. I’ve downloaded the beta 2.5 from food4rhino and replaced with the existing kangaroo, but after that the missing components became even more. I tried to download them using the download button on the dialogue box but nothing have changed. how can I find kangaroo 2.5.2 ?

I don’t have food 4 rhino…
I think you just need to update rhino/grasshopper… (?)

I did update it, it didn’t work

seems like the last stable version is 2.42

Please post a screenshot about the errors/warning you get at the opening of the file.
I think I didn’t use any plugin… but you make me doubt about it now…

The latest version of Kangaroo is included as part of Rhino 6. If you have a recent service release of R6, you don’t need to install any Kangaroo from Food4Rhino

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It looks like you need to update your Rhino service release (Help>Check for updates)

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I just updated rhino and ran your algorithm. its unbelievably clean and perfect. unfortunately its not what we need tough. this is not about testing just any chain, actually every necklace we make is different and consists of different pieces. I upload an example

we need something which works for different necklaces. as you have already said, maybe we need to use some other software like blender. but we only have rhino and we use rhino to design, its not an option for us to learn another software or even afford it right now.

Thank you again for your great effort and beautiful work

Maybe you can create surface under the necklace and project it on the mesh than use Sborph

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that wont simulate the behaviour

For this kind of works i prefer use Professional Softwares
This is an old work from Rhino to Realflow to 3dsmax

Your model is very detailed, i don’t think you can get what you want with Grasshopper

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Here’s another way, it has it limitations and unfortunately it’s not in Rhino/GH. but in Zbrush
If your need is to make the necklaces look as they would worn on the body? I think you can get nice results with plenty of tweaking control for flow gravity and arrangement.
This is probably true with other methods, that to draw a chain in which each link is different, is much more challenging, in the following approach you draw a chain that is comprised of a start link [can be the lock] the regular links and an end link.
you can then do what ever you want with this, including changing the the type of chain in 1 click,
in order to have various type of links [like in your example] you can afterwards swap any of the individual drawn links with different ones.

HTH
Akash

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unbelievable! thank you very much

That’s exactly what I want! Thank you very much

This with transformation tools

mannequin.gh (764.7 KB)

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Although this is not exactly what I was looking for, I really enjoyed your clean and light-loading code. it helped, thank you very much.