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RopeGN: Geometry Nodes group for simulating ropes (lemmy.ml)
submitted 1 week ago by to c/blender@lemmy.world
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Blender doesn't provide a built-in simulation capabilities for 1D objects such as ropes. One could fake that with a narrow-mesh cloth simulation, but the result is not good enough. RopeGN implements the XPBD algorithm (also used in Blender's cloth simulation) with some tweaks and sauces specific to 1D manifolds which makes it more effective, accurate and much faster.

Here's the master repository from which you can download this node group, and where I'll be adding more stuff in the future: https://github.com/haykh/GeometryNodes

Post the cool stuff you've done with this in the comments : )

PS. Also, I'm not really distributing this through any other channels, since most markets request for payment info even for free assets. So if you like this and can -- please spread the word!

PPS. There are some example simulations which I couldn't attach to this post in the README of the subdirectory: https://github.com/haykh/GeometryNodes/tree/master/RopeGN

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[–] [S] 7 points 1 week ago (1 child)

The node basically simulates (just like cloth simulation) a 1D manifold (a thin cloth if you will) and spits out the simulated mesh (at each frame). What you do with it is up to you. Like in the cover image of this post, i chained a couple more geo nodes to make it into a proper rope.

So for something like a chain, you could add another geo node after the RopeGN (like in the attached image).

Spiderweb is an interesting case, but it won't work with this modifier, because it inherently has internal loops. I think a cloth simulation would be much more feasible for that. And this is deliberate: the whole point of only doing for 1D objects (single loop is ok) is it allows to simplify and speed up the XPBD by quite a lot (for the nerds: the Jacobian is sparse if you only have nearest neighbor connectivity).

For the barbed wire -- I'm actually not sure. You can probably tweak the parameters to get something that resembles it, but I think a barbed wire also has lateral elasticity which normal ropes do not, so it won't properly model their dynamics.

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  • [–] 2 points 1 week ago* (last edited 1 week ago)

    This is remarkably detailed, thank you so much for your hard work. Admittedly, this is a little bit advanced for me, I'm only just starting to learn Blender. But I'll be glad to have this tool when I do learn how to use it.

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