Is this 3D?

[trusktr]

If not, do you know of a comparable 3D physics library?

[zhaoyong7]

three.js

[1j01]

This isn't 3D, and Three.js isn't a physics library, although there are several Three.js physics engine integrations. I don't know of any 3D physics engines that are "point-based" in the same way.

[forresto]

https://particulatejs.org/ is somewhat similar and solves 3D systems, but doesn't have stiffness in the constraints.

[1j01]

This example (source) seems to have stiff constraints. I don't know that it's adjustable though.

[forresto]

https://github.com/mattdesl/verlet-system is another lib that works in 3d.