Basic Footroll Tutorial
By, Tyler Thornock

Alright, this tutorial is a footroll tutorial, similar to the reverse footlock you have probably seen with joints, just using group nodes instead.  Various people have asked me for help setting up a footroll properly so I made this quick tutorial to help them.

- Start by creating a normal biped leg.  Name it appropriately, hip, knee, ankle, ball, toe.
- Create an ikhandle from the hip to the ankle called Leg_ikhandle, then another ikhandle (prefereable using the iksc Solver not ikrp) from the ankle to ball called Ball_ikhandle and one last iksc handle from the ball to the toe called Toe_ikhandle..
- After that create some kind of control for the leg and snap it to the ankle joint, freeze transforms, and delete history.
- Now select each ikhandle, group them, and set the pivot point of the group to the location of the end of the ikhandle (the thing you would click to select the ikhandle).

You setup should look like this in the outliner so far.

- Now time for the magic of parenting :) Parent all the group nodes under the control.  Now parent the Leg_IK group to the Ball_Roll group and the Ball_Roll group to the Toe_Roll group.
- If you rotate the Toe_Roll or the Ball_Roll group nodes it will rotate the leg appropriately.
- All that is left now is to create attributes on the control that will drive the rotate of the group nodes.
- Add an attribute called toeRoll and another called ballRoll.
- Open up the connection editor and connect the custom attributes to the appropriate group node, most likely the rotate in X.

Wahoo, you now have a basic footroll.  If you want to be able to pivot on the sides of the foot or heel simply group the Toe_Roll, set the pivot point to the correct location, create a custom attribute on the control and connect the rotates appropriately.  If you need help creating the pole vector so it does move when you apply the constraint see the ik/fk switch tutorial.

Sample File from tutorial.