Hello all, I’m building a muscle rig that will be able to be moved between models so you won’t have to create a new muscle rig for each character. Similar to this. https://zivadynamics.com/resources/anatomy-transfer
The goal is to animate in Blender and move to Houdini where I will have an Muscle rig HDA(using their new vellum muscle system) that deals with the simulations side of the muscles, skin, and fat. Which because it’s procedural, after building the asset you/I won’t have to make that many tweaks! Eventually, I plan on releasing the rig for free(with donations) or charge only 5-10 dollars for it.(I can charge more, but I want it cheap because my past self would want something mess with.)
On top of that will be skin deform bones so you can animation both the bones and character mesh at the same time, with a mesh deform cage on top to better match the muscles
I was able to build the rig with everything, the bones to deform the mesh, the bones to correction move the skeleton, but the main issue I’m having is after setting up all the constraints, IK’s scapula rotation, bones movement, etc. Setting up deform bones with stretch(ik and stretch to) completely overrides any other constraint and parents on the bones.
For example, if I have IK on the forearm and if I add an stretch constraint to the humerus, it invalidates the IK, even if it’s off. Adding stretch is the final thing I need to do for this rig and I nearly threw my computer out the window last night trying to get it to work.
Another issue I’m having is the clavicle-humerus rotation, I can get the scapula to follow the correct rotation using a transformation constraint which follows the rotation of the humerus, but I think because the humerus needs to be connected to the clavicle(or at least I think it does with my limited knowledge, especially when it comes to stretch) I can’t create the same relationship.
My hierarchy is skeleton deform bones(adding stretch is causing issues) → mesh deform bones(bones have relationships with the skeleton deform bones) → Animation bones(ik’s, twist, etc)–> mesh deform cage(for matching muscle to mesh).
I’ve been banging this out for the last few days and this is the last step before I can move onto dealing with the muscles. Any help would be greatly appreciated!!
Here’s an basic file of just the shoulder and arm, in my main file the radius and ulna rotate correct, this is just to help with the constraints - https://drive.google.com/drive/folders/1q0CGYUOFA7CjQcuhM5s-dKc5BFgVwKmv?usp=sharing
One workaround I was think it making to rigs, have the stretch bones on one rig and everything else on the other. And when done stretching, apply the stretchy bone rig and then activate the other rig and it’s constraints, but the issue with that is it’s really destructive and if the file corrupts or you lose data then you will lose the stretchy bone portion.