Caveman Leg Rig Tutorial

[Buzzy]

Ok, another member, FreeSpace, asked me how I rigged my Caveman character's legs (the animation can be found here).... so I decided to make a little tutorial. Its for 3ds Max. Here goes.

First, he has two bones in the leg (thigh and shin) and 3 in the foot (Heel, Ball, and Toe) all linked and parented from the hip down. Like this -


Next, add three HI IK chains. The first is the primary one to move the leg... Its a 2-bone chain, starting at the hip joint and ending at the ankle joint. The other 2 are only one bone long...one starting at the ankle, the other starting at the middle of the foot and ending at the toe. Here are the 3 IK Chains -


Now, create 6 points and align one on each of the IK goals. Make the 4th one a little bigger and align it to the middle goal. The 5th one should be placed out in front of the knee joint, it will control the direction the knee points. The 6th one should be place somewhere over the foot and will be what keeps the foot stable when the leg moves side to side. Make sure these last two points are lined up exaclty in front of the vertical axis of the leg. Here are the points all in place -


Ok, now the confusing part....linking. First, link both points at the middle to the toe point. Link the toe point to the ankle point. Link the IK goals at the ankle and at the middle of the foot both to the smaller point at the middle. Link the IK goal at the toe to the bigger point at the middle. Here's a pic...hope it's not too confusing -


Almost done... Now, select the ankle IK Goal and go to the Motion Tab. A little ways down you'll find "IK Solver Plane" and a button labelled "Pick Target". Click this button and then click on the knee direction point. Now, if the point wasn't exactly in front of the leg, the leg will snap over so its pointed directly at it, which may screw up the angles of the foot bones. So make sure its directly in front.


Now, do the same for both the middle IK chain and the toe IK chain, but use the foot stabilizer point for both of their solver planes. Now, the last thing, create an NGon around the foot, convert it to an Editable Spline, and shape it so it roughly outlines the foot.


This will be what you use to control the whole mess. Link the point at the ankle and the 2 solver plane points to the foot controller you just made. Hide everything but the foot controller, the knee solver plane point, and the two middle points. All done! Yay! Now here's how it works.... the foot controller will control the position and angle of the foot as a whole.... the knee point will control the angle of the knee. The smaller point in the middle can be rotated to lift the heel off the ground, but keep the toe planted. The bigger point can be rotated to lift just the toe off the ground without moving the heel.