Controlling rotation direction in IK

[ofer]

Hi,

I have a little problem with a small IK chain. I hope I can explain it well.

I built a simple 2-bone chain, and added IK to this chain. The problem is that when moving the end affector, the angle between these two bones causes the IK solver to bend the chain inward (making that angle smaller), but I actually want it to bend the other way around. This is not very natural, but I'm rigging a robot. I tried to rotate the bones before applying the IK, and also tried to use IK with constraints but it didn't help. It seems the solver only bends in the direction of the original angle.

Is there any way around it?

Thanks.

[edward]

The IK solver always solves from the Rest Angles parameter on the bones (second tab). If you want it to bend the other way, then you can put expressions into the rest angle parameters so that the IK rest bends the other way. To visualize the rest angle parameters, choose from the top menu, Edit > Objects > IK Rest.

[ofer]

Thanks. Thats an interesting tool.

But even when using this tool, the chain just switch direction, and the original shape is changed.

I posted a HIP to illustrate what I'm trying to achieve.

You can see the chain animated. If you look at it from the front view, I want bones to bend inward (to the right) as the origin

moves up and the goal to the right. But at the same time I want it bent outward (to the left) as the origin moves down.

And if it is possible to achieve that effect without moving the goal, even better.

ik.hipnc