How to Keep the Toe Bone Parallel to the Ground Using IK Constraints?

cihpargx

Hello,
In my project, just like with the SpineBoy character, when I move the character, the toes automatically stay parallel to the ground. I reviewed the constraints system, but I think I couldn’t achieve this behavior.

Hierarchy:

Hip
------Leg1
-------------Leg2
--------------------Foot1
----------------------------Foot2

I applied an IK constraint to Leg1 and Leg2. A “Target1” point was created for this IK constraint.

Then I applied another IK constraint to the Foot1 bone. A “Target2” point was created.

I positioned “Target1” under “Target2”.

So far, everything works fine.

However, I couldn’t set up a constraint for the “Foot2” bone. What should I do to keep this bone consistently parallel to the ground?

Spinebot

To keep the Foot2 bone parallel to the ground, you need to disable Inherit Rotation on that bone. This is the same technique used in the Spineboy setup.

How to do this:

Select the Foot2 bone in the tree
In the bone properties, uncheck the Inherit Rotation option

This will ensure that the Foot2 bone doesn't rotate when its parent bone (Foot1) rotates, keeping it parallel to the ground at all times.

Example from Spineboy

Why this works:

When you disable Inherit Rotation on Foot2, it ignores the rotation of its parent bone. This means even when Foot1 rotates due to the IK constraint, Foot2 maintains its original rotation relative to the world, keeping it flat on the ground.

This is exactly how Spineboy's feet work - the front-foot-tip bone has Inherit Rotation disabled to prevent the foot from going through the ground when rotating its parent bone.

Your complete setup should be:

Leg1 + Leg2: Controlled by first IK constraint targeting Target1
Foot1: Controlled by second IK constraint targeting Target2
Foot2: Inherit Rotation disabled (no constraint needed)

This approach gives you full control - you can rotate Foot1 for the ball of the foot while Foot2 stays parallel to the ground automatically.