Adjust bone orientation

So the problem that exists in Blender and bone orientation is the forward axis of the bones, currently when any bones are created or imported the bone points in the direction of the Y axis.

This is an issue when using skeletons from other software, or trying to collaborate on a project with different artists, an issue that still exists no matter what export/import settings are used with FBX.

A recent example I have is using a skeleton from 3DS Max, I was to rig up some items of clothing for a character, the only way to do this in blender without issues was to let the rig import as shown below, workable but not very user friendly, especially when I'm to add more animations.

I imagine fixing this would require digging deeper in to the blender code as there doesn't seem to be much in solutions out there already, so these suggestions are more of a 'how things could work' without knowing specifically how it already works under the hood.

The first is a simple fix, it would involve just orienting the visual of the bones, it could live under viewport display as it is purely visual. This would fix the above issue of usability, but not really the problem of having actual X forward bones.

This would mean that creating any extra bones are still Y forward and would be created sideways visually (if you are not set to view Y forward) but it's a quick work around for importing existing rigs and adding animations.

The second fix would require a lot more work but would put options under the armature menu whilst in edit mode.

'Bone Roll' popout could become a 'Bone Orientation' popout, where you are able to convert the forward axis of bones instead of just changing the visuals.

This could provide extra options such as:

• Convert existing curves = if a model has rotation on the upwards X but you now want to have X be fowards instead, you would choose the secondary axis that is to take the curves from the old X axis.
• Apply visual only = the visual roatation of the bone is changed to point along the selected axis instead of the axis rotating to point along the bone, this would be used in cases like above when importing other rigs with different forward axis.

This problem probably needs a lot more research on my end to fully understand the limits, but it's definitely a needed change at some point as it's one of the biggest things holding Blender back from being part of the animation pipeline in games when collaborating with other artists.