Using IK to align a character's feet to the ground

In this section, you will learn how IK can be used to modify an animation so it looks more correct. Specifically, you will learn how to use IK to stop a character's feet from going through the ground when walking over uneven surfaces.

Now that you can solve IK chains using CCD or FABRIK, let's explore how these solvers can be used. There are two common uses for IK, that is, to position hands or to position feet. In this section, you will explore what it takes to clamp a character's foot to the ground as the character is walking.

To solve foot clamping, you could check the last global position of the foot against the current global position. If the foot motion hits anything on the way, pin the foot to the ground. Even the most trivial solutions have edge cases: what happens if the up motion is too far away? At what point in the animation cycle can we interpolate between pinned and non-pinned positions?

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