# Planar IKs?

Is there a way to constrain IK handles to a planar motion? In humans, joints only ever move in a plane and any rotations happen about the root joint. Maya uses rotate plane solvers to simulate this. Can I do similar in Blender?

I’m also wondering if you can lock movements in general. For example if I only want to allow a bone to rotate in z but not x or y.

A final question, is there a way to transform in 2 axes at once but not the 3rd? Like you can do s to scale a model in all directions and s then the axis name to scale in one axis but is there a way to scale in both x and y simultaneously but not z without doing it separately in x then in y?

isn’t this exactly what the locked axis constraint does?

where do i can find the lock axis constraint? is it in the add>constraint?

yeah

it is locked track

there is no constraint to only allow rotation on one axis, but this will track on only one axis

[there is a difference, but you ought to be able to achive the same things with this]

isn’t this exactly what the locked axis constraint does?[/quote]

I think you’re right. I checked the documentation and it seems that the locked axis is supposed to constrain to a planar motion but I don’t know what objects to use for the constraint.

To be more specific, I have an IK handle attached to the wrist and I want it to move in the plane defined by the x,y axes of the upper arm bone. So, I have the upper arm bone, the lower arm bone and the IK bone. What do I enter for OB and BO in the constraint?

I tried Armature for OB and the upper arm bone for BO but when I move the IK, the arm isn’t constrained to a plane. The IK can move just as freely as if there was no constraint.