Why Moving Bones in Smart Bone Actions Can Hurt Character Rotation

[Aziz]

While experimenting with character rotation in Moho, I noticed that using bones inside Smart Bone Actions doesn't offer much benefit—especially when working with complex characters like birds, where we want to rotate the body from right to left.

For example, rotating the head using Smart Bones works fine, as the head is usually a simpler structure. But when it comes to rotating the body, which often includes multiple bones connected to vector points, problems start to appear. Moving bones inside a Smart Bone Action often leads to deformation and makes it harder to achieve smooth and creative vector control.

In my opinion, what really matters inside a Smart Bone Action is the ability to manipulate the vector points directly. Moving bones inside the action tends to get in the way and can ruin the result. It would be better if bones remained linked to the points on the regular timeline, but within the Smart Bone Actions, we shouldn't have to rely on bone movement.

What I (and perhaps others) would love to see is the ability to move bones freely inside a Smart Bone Action without them affecting the connected points—so we can shape the motion more creatively without breaking the form or structure.

Does anyone else feel the same? Or maybe someone has found a practical way to work around this limitation?.

[Hamedss]

I do not understand. you want disconnect points from bone within action?

[Aziz]

I do not understand. you want disconnect points from bone within action?

Yes, exactly. Because when there are multiple bones, especially during rotation, their movement often distorts the shape. In most of my characters, I barely move bones inside Smart Bone Actions — only in very limited cases.

It would be much better if we could choose whether a bone stays connected to points inside a Smart Bone Action. For example, each bone could have an option to enable or disable its influence during the action.

And by default, it would make more sense if bones were not connected during Smart Bone Actions — that way, we’d have more precise control over the vector shapes without unwanted deformation.

[Hamedss]

This is annoying if you forget set bone strength to zero before entering the action . I never use make smart dial bone in bone menu. Just creating a bone. Set strength to zero and creat action for it.

[Aziz]

This is annoying if you forget set bone strength to zero before entering the action . I never use make smart dial bone in bone menu. Just creating a bone. Set strength to zero and creat action for it.

I didn’t mean bone strength — I was referring to point binding (Bind Points).

For example, let’s say we have a bird character, and the body is controlled by two bones. When we try to rotate the body in a Smart Bone Action, we naturally have to move the bones — meaning the right-side bone needs to move to the left, and the left-side bone to the right — in order to match the mirrored rotation.

But the issue is that the vector points are bound to these bones, so when the bones move, they deform the shape in unwanted ways.

That’s why I think the best solution would be for point binding to be disabled inside Actions — or at least in Smart Bone Actions — while staying active on frame 0 or in the regular timeline.

Even better, if we had an option in the Actions panel to enable or disable bone-point binding during an action, that would give us much more flexibility and control.

[Hamedss]

Oh . I thought you talking about bone strength. But this is not common in any animation software but possible. Did you saw this in other animation software? For example in 3ds max the skin modifier effect can not disable during reaction manager.
But really nice idea. Disable binding and flip the bones.

[Aziz]

Oh . I thought you talking about bone strength. But this is not common in any animation software but possible. Did you saw this in other animation software? For example in 3ds max the skin modifier effect can not disable during reaction manager.
But really nice idea. Disable binding and flip the bones.

I haven't seen this feature in any software — it's just an idea that came to mind while working in Moho.

In 3D software like 3ds Max, you usually don’t need to disable point-to-bone binding because everything moves in 3D space, and the deformation is handled differently.

But in 2D animation software, especially when rotating characters, keeping the points bound to bones during Smart Bone Actions often causes distortions. That’s why I thought it would be useful if we could temporarily disable binding inside an action to have more control over the vector shape without being affected by bone movement.

Glad you liked the idea!

[jayfaker]

I understand where you are coming from. The way I am currently rigging feet, I am trying to do it more like they do in 3D software. So I can rotate the feet in "3D" space, but have the bones controlling the feet also follow the rotation (both by rotating and scaling the bone) so I can still bend the foot correctly. Basically a smooth alternative to vitruvian bones.

So what I've been doing is in the smart bone action, move the bones first, which warps the points in crazy ways, but then I move the points to the new pose. Gotta have reference of the different angles beforehand, though. Also, it does risk having all the points go crazy in between the poses, which could be a pain, but so far I've had pretty good luck with it.

But yeah, I think having the option to disconnect the bones from points on an actions timeline is a great idea and would make this work far better.

[jayfaker]

This is what it looks like when it works.