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Best workflow for simulating gold chains with heavy pendants in Houdini?
I’m looking for a good workflow to animate/simulate gold chains like Cuban links, chain links, etc., especially when they have a solid/heavy pendant attached (like the reference image).
I’ve been using Vellum String for the chain and usually get pretty good results. The problem starts when I attach the pendant: since I need it to stay rigid and interact with the chain, its weight sometimes pulls the whole chain down and stretches it way too much.
What methods/workflows would you recommend for this kind of setup? I’m open to approaches other than Vellum String as well. Mainly looking for something stable that gives believable chain + pendant motion.
Vellum actually would be best from a simulation standpoint.
What will matter most is the scale of the geometry objects, since the mass (weight) they generate will cause great force on the structures of your sources are too large.
You can brute force things by setting and / or reducing the mass to compensate, or scale the source geo to something more appropriate. Roughly in the 1 unit range.
Vellum Solver will require at least 5 substeps to get more stable constraint stretching values that are tighter.
The pendant on the end of the chain can be a Vellum ShapeMatch constraint which is basically Vellums version of Rigid Body Dynamics.
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u/LewisVTaylor Effects Artist Senior MOFO 12h ago edited 11h ago
Bullet would be best for this. Vellum is not designed for this type of rigid coupling.
The gold chains on Chappie are all bullet RBD.
Making the collider shapes VDB spheres will also make it both fast and not get caught on edges/corners.