2009

IK Limb Solver

The IK Limb solver is specifically meant for animating the limbs of human

characters; for example, the hip to the ankle, or the shoulder to the wrist.

Each IK Limb solver affects only two bones in a chain, but multiple solvers

can be applied to different parts of the same chain. It is an analytical solver

that is very fast and accurate in viewports.

To use the IK Limb solver, a bones system must have at least three bones in

the chain. The goal is placed at the pivot point of the bone that is two bones

away from the first selected bone.

The IK Limb solver works not only with bone hierarchies, but with any linked

hierarchy that has at least three elements, and is set up to model a human

limb. The additional requirements are:

■ The first joint is "spherical." That is, it has three degrees of freedom.

■ The second joint is "revolute," a robotics term that means it is based on a

pin and has one degree of freedom.

The IK Limb solver uses the same controls as the HI Solver, so it allows for

mixing periods of forward and inverse kinematics in the same animation

period. It does not use the HD Solver methods of damping, precedence, and

setting joint limits, instead it has a preferred angle parameter, swivel plane

and IK/FK Enabling.

The IK Limb solver can be exported directly to a game engine.