Feature Request: Bone Scaling & Deformation Support

Feature Requests Engine Features
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Feature Request: Bone Scaling & Advanced Bone Deformation Support

I’d love to see Roblox support bone scaling (and, if possible, more advanced bone deformation such as Blender’s Bendy Bones) for skinned meshes.

At the moment, bones only support translation and rotation. Since they’re currently derived from Attachments, scaling information is discarded, meaning animations relying on bone scale or bend deformation cannot be imported or recreated in Studio. This limitation has also been discussed in previous DevForum threads: the long-running Bone Size Property feature request (Bone Size Property) and the Bendy Bone Rig Not Working (Roblox/Blender) support thread (Bendy Bone Rig Not Working (Roblox/Blender)).

Why this matters

This affects a lot more than just stylized animation.

Many modern rigs rely on bone scaling or procedural deformation for things like:

  • Muscle flexing (biceps, forearms, calves, etc.)
  • Squash & stretch animation
  • Bendy limbs, tails, tentacles, and spines
  • Facial rigs
  • Hair and cloth maintaining volume while bending
  • Creature transformations where body parts grow or shrink

Without bone scaling, creators have to build complicated workarounds using many extra bones to approximate volume changes. These rigs are harder to animate, harder to maintain, more expensive to evaluate, and still don’t achieve the same quality as native scaling.

Likewise, Blender’s Bendy Bones are effectively unusable after import because Roblox only imports the underlying bones and not the deformation behavior, forcing artists to replace them with long chains of rigid bones.

EditableMesh

Now that EditableMesh exists, I was wondering whether supporting bone scaling and deformation is more technically feasible than it was when skinned meshes were first introduced.

Even if full Bendy Bone support isn’t practical, features such as:

  • Bone scale animation
  • Uniform or non-uniform bone scaling
  • A Bone.Size or similar property
  • Support for importing bone scale from FBX/glTF animations

would already unlock many workflows that are currently impossible.

Existing interest

There has already been significant community interest in this area:

  • The Bone Size Property feature request has accumulated substantial support from developers who want bone scaling for animation, character customization, and procedural effects.
  • Multiple Blender users have reported that Bendy Bone rigs cannot be transferred to Roblox and are forced to rebuild them using traditional bone chains.
  • Here is also an application on my part of bendy bones and scaling bones that are not replicated to roblox :
  • Example of how bendy bones and scaling works in blender :
  • Example of an actual animation within blender :
  • Example of how the animation plays in roblox studio (we can see that the stretching is behaving differently because bendy bones in roblox is exported as 1 singular bone)

Closing thoughts

Roblox has made huge improvements to the avatar and animation pipeline over the past few years, especially with skinned meshes and EditableMesh. Bone scaling and more advanced deformation feel like one of the remaining missing pieces that would bring Roblox much closer to the animation workflows available in Blender, Maya, Unity, and Unreal.

Even support for basic bone scaling would be a massive improvement for character artists and animators, while laying the groundwork for more advanced deformation features in the future.

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