I have a curve. I need to somehow rig it so that I can smoothly "unbend" it at its "elbows"; I need it rigged so that I can bend it bag and forth at will.

I haven't been able to figure out a way to bend it open so that the "elbow" becomes completely vertically straight curve when "unbent"; it seems that no matter what I try it always has a nasty weird V-ish shape at the elbow even when unbent. Of course, part of the difficulty is the fact that the curve has quite a few points. Unfortunately due to the nature of the project, I have to have the curve be as smooth as it is around the elbows (it's used for array duplication of zipper teeth).

Also, due to the nature of the project, the curve's initial position is important--so I can't start with it unbent and rig it to become bent, for example.

I've included an image showing the the starting shape and the desired end shape.

Rigging it so that it can smoothly bend at the "elbows" seems like it should be so simple, but I can't seem to accomplish it. Any ideas?

enter image description here


2 Answers 2


The problem is that you have too many control points on the curve, which makes it hard to control.

Would be best if you could fit a bezier or bspline curve to the shape of your curve with less control points.

You can control curve(s) with vertex hooks modifiers pointing to bones. Add an armature and make a bone in every curve's control vertex location. Select bone in posemode, shift-select curve, enter edit mode, select control vertex at bone's location (or multiple points if there are many in line), Ctrl+H+Make Hook to Pose Bone.

Then pose the bones so they are straight. You can parent them into a chain and position them by rotating the parents, so the curve points move naturally in an arch.

The more control points the more tedious it is. This process can be however scripted easily.

  • $\begingroup$ Thanks! Yes, this is what I ended up doing. The curve was generated from the mesh (because its specific position was important) but I was able to reduce the points around the elbows and do a single hook for the top points, a single hook for the bottom points, and one-hook-per-point for the elbow points. $\endgroup$
    – Pete
    Nov 1, 2015 at 3:48

I'd suggest converting your curve to a mesh, then rigging it with bones. It seems like how you are moving the curve can easily just be accomplished by bones that control a mesh.


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