Any ideas of solution for this?
preferably using bones and drivers. I could do it through geometry nodes, but would prefer it to be compatible with older versions
preferably using bones and drivers. I could do it through geometry nodes, but would prefer it to be compatible with older versions
There are a couple of different approaches you can take.
It might be worth moving the knee joint a little further into the leg, so it’s not quite so close to the surface.
To help with the deformation, you could add some extra bones to give more control. Their positions can be adjusted by drivers based on the main leg rotation.
You’ll get the most control with a blend shape to sculpt the mesh into a nice form in the bent leg position. This can also be driven by a driver as the leg rotates.
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As magpie offered, the bone looks not placed quite right, a bit too far forward. The weights also look a bit sharp. And corrective shapekeys are a perfectly reasonable solution.
In terms of pure armature solutions, there are a few. If using a thigh twist bone (a good idea anyways), you can push the thigh twist bone out a bit, possibly via constraints like limit distance/outside. You can use a fan bone at the knee to improve things. You can use a three-bone knee, or bendy bones to do the same thing as a three-bone knee (or spline IK to do the same thing too, that’d be pretty weird but I’m getting a lot of use out of spline IK lately.)
In terms of other modifiers, you can use a mesh deformer instead of directly armature deforming, which allows you to use low poly, volume preserving knee topologies. @Hadriscus has talked elsewhere about using a cast modifier, from empties parented to the leg bones, to squish the legs apart.
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not sure that was me, doesn’t ring a bell
But I would start by watching some reference on knee placement and movement : https://www.youtube.com/watch?v=wyiJw034ssA
And remember your control rig (the controllers) doesn’t need to match your deform rig 1:1. This means you can set up more intricate joints, using several bones if necessary, yet control them via your two “simple” leg bones
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That’s all very good advice, thanks. I did what I could with mesh editing and fan bones. Maybe I’ll research three bone knee later; it seems to be more anatomically accurate. I usually avoid using shape keys since sometimes I need to alter proportions by applying Armature modifier.
