Scale joint in other angle than joint axis?

[malouise]

I want my character's body to be able to squash and basically be able to become flat on the ground. Problem is that when the hands are rotated, they scale relative to the joint axis instead of the body/world, so they don't become flat like the rest of the body. So my question is, is it possible to make the joint scale in another angle? Or any other way to do this squash effect?

I attached an image trying to illustrate what I mean.

[Kahylan]

Hi!

If you want to create this effect Joint based, how you achieve an effect like this depends on multiple things:

- How your controls are set up

- If there are already connections on the scale attributes of your

- What way your axis are facing

- How much your model needs to do when squashed

- etc...

Each variable slightly changes how you need to approach this problem and also what issues it potentially causes later on. If you really want to go joint based, having all your joints in the same World orientation first is probably the best way to go.

But, there is a quite easy solution to achieve this effect without having to scale the joints. Which is to just attach a Lattice to your mesh in the deformation order after your skincluster.

The Lattice only needs 8 Points since you want to squash the entire model equally. It should be quite a bit bigger than your rig, so the mesh doesn't accidentaly exit the cage. And both the deformer as well as the deformer base should follow the main control you use to move the character (Root Control, Transform Control) so the Model stays within the Lattice and doesn't deform when you don't want it to.

This has the upside that you don't need to scale your joints, so you wont have any accidental squashig or stretching on limbs and you don't run into problems with joints that are already scale constrained to something. And it is really easy to set up. The downside is, that your mesh when squashed moves away from the rig, so you have to do mental gymnastics to animate the squashed mesh with the unsquashed rig. So if this option is feisable for your project depends on how often you need to do it.

I hope it helps!

[malouise]

Hi, thanks for the reply!
This character rig will be used in a game engine, so I can't use the Lattice deformer unfortunately, it has to be joint based. How do you set up world orientation on the joints?

[Cagetron · Accepted solution]

I think you're just running up against the limits of joint based deformation and games. Joints have a local orientation that can be aligned any way you want, but once you start animating cannot change. For ease of animation it's best that they be oriented down the chain so when you twist a joint it doesn't happen at a weird angle. Postive X aligned down the chain is pretty standard as the "twist" axis. 

Backing up, is this for some kind of impact effect where the character is slamming into the ground?  You might be focused too much on the details of the deformation. Think about how you can incorporate joint scale along with your POSE and TIMING to create the impression of a forceful impact.  Try to mostly scale the spine and head if you can, don't worry about the limbs so much. Hope this helps.

[malouise]

Thank you for the explanation, now I understand a bit better!