Blender has many ways of adding soft-body simulation, but I’ve always found it takes a while to get it right. I often want to add just a simple ‘lag’ action to pieces of the model, such as antennae, backpacks, hair strands etc. I made this add-on some time ago in an ugly sort of way and I’ve found it handy. I gave it a re-vamp, ported to 2.8 and thought I might share it in case it’s useful for someone else…
Instructions and download link: https://github.com/nerk987/RigFlex
(There’s a 2.79 version in the releases tab as well)
Simple instructions for using:
- Select the deform bones in your rig that require the soft body treatment
- From the RigFlex tab in the sidebar, hit the Initialize button which will
- Duplicate the bones into a new bone layer
- Add a ‘copy transform’ to the new bones so that they follow the original bones for now
- Modify objects with an armature modifier, or parented to the original bones to use the new bones
- Animate the model as required, then use the RigFlex ‘Bake’ button which will
- remove the ‘Copy Transforms’ constraints
- add keyframes to the new bones to simulate a very simple soft body action over the specified range
- To change the animation, use the ‘Free Bake’ button, and ‘Bake’ again after the change.
More detailed instructions:
Note: I’ve used a very simple simulation model on purpose. It’s just a ‘first order’ lag with a single ‘stiffness’ parameter from 0 - 1. A mass/spring/damping model isn’t that hard to code, but it’s hard to get the right result without a lot of fiddling. I just wanted a no fuss result. The other soft body methods are still available if required.
Also, not long ago I noticed an older add-on which has a similar aim. Jiggle Armature. If you haven’t seen it, you may want to check it out as well. Thread here: https://blenderartists.org/t/jiggle-armature-2