Scaling Armature Distorts IK Constraints

[DavidBrennan]

This isn't really a full Bug or anything, but it is a pretty major inconvenience when you're working with the Rigs in Blender.

Basically, when the .MHX is imported to Blender, you can only scale the whole Armature via Object Mode because, if you try scaling the Root Bone in Pose Mode, that results in the Mesh getting all skewed and distorted.

So, you instead just scale it in Object Mode. In the past, that was no problem. However, I just used Alpha 1.7 for the first time, but now when the Armature is scaled in Object Mode, the IK Constraints are all skewed. (And you still can't scale the Root Bone in Pose Mode, either.)

So, I guess this is a request for the .MHX Rig to allow for proper scaling. Does anybody have any suggestions about how to work around this, currently?

Here's a .Blend and a screencap:

http://www.pasteall.org/pic/48227

[ThomasL]

Did you try to change the Scale parameter on import? It is there for a reason.

[DavidBrennan]

ThomasL,

As I noted in my post, the problem only arises when trying to Scale the model within the program. Yes, when it is imported at its defined size (including the Scale value in the Import MHX dialogue), then the Rig works great (it is even better than Rigify, in my opinion). But there are going to be many, many, many situations where a user will need to change the Scale of his model later on (whether it's for animation or because he realized he miscalculated it earlier or many other possible reasons). In these situations, the Rig does not work properly.

Essentially, as the .MHX rig is now, it basically cannot be scaled after it has been imported. This seems to be a big imperfection to me.

[ThomasL]

Well, I don't think there is any way to scale the rig once it is imported into Blender. Not only the bones need to be scaled, but also some constraints (e.g. the StretchTo constraint has a rest length), and perhaps other stuff as well. If you want to scale the model in Blender, you need to track down all such cases as well.

[DavidBrennan]

So the problem persists: If a user needs to grow a character (say, for an animation) or if he miscalculated the size of one character upon import relative to others....then he's screwed. Whereas with Rigify or any other Rig system, he can simply scale the Root Bone or the whole Armature Object itself, here, the size is completely locked, and his options are severely limited.

So this is a flaw in the MHX Rig, in my opinion.

[ThomasL]

Note that Rigify does not do deformations - it is a control rig only. It is mainly deform bones that simulate muscles that have StretchTo constraints, which is beyond the scope of Rigify.