2009

Four plug-in IK solvers ship with 3ds Max:
■ HI (History-Independent) Solver on page 3392
The HI Solver is the preferred method for character animation, and for any
IK animation in long sequences. With HI Solvers, you can set up multiple
chains in a hierarchy. For example, a character's leg might have one chain
from hip to ankle, and another from heel to toe.
Because this solver's algorithm is history-independent, it is fast to use
regardless of how many frames of animation are involved. Its speed is the
same on frame 2000 as it is on frame 10. It is stable and jitter-free in
viewports. This solver creates a goal and an end effector (although the
display of end effector is off by default). It uses a
swivel angle on page 3397
to adjust the solver plane to position the elbow or the knee. You can display
the swivel angle manipulator as a handle in the viewport, and adjust it.
HI IK also uses a preferred angle to define a direction for rotation, so the
elbow or knees bend correctly.
■
HD (History-Dependent) Solver on page 3422
The HD Solver is a solver well-suited to use for animating machines,
especially ones with sliding parts that require IK animation. It lets you set
up joint limits and precedence. It has performance problems on long
sequences, so ideally use it on short animation sequences. It is good for
animating machines, especially ones with sliding parts.
Because this solver's algorithm is history dependent, it works best for short
animation sequences. The later in the sequence it is solving, the longer it
takes to calculate a solution. It allows you to bind the end effector to a
follow object, and it uses a system of precedence and damping to define
the joint parameters. It allows for sliding joint limits combined with IK
animation, unlike the HI IK solver, which only allows for sliding joint
limits when using FK movement.
■ IK Limb Solver on page 3444
The IK Limb solver operates on only two bones in a chain. It is an analytical
solver that is fast in viewports, and can animate the arms and legs of a
character.
The IK Limb solver can be used for export to game engines.
Because this solver's algorithm is history-independent, it is fast to use
regardless of how many frames of animation are involved. Its speed is the
same on frame 2000 as it is on frame 10. It is stable and jitter-free in
viewports. This solver creates a goal and an end effector (although the
display of end effector is off by default). It uses a
swivel angle on page 3397
to adjust the solver plane to position the elbow or the knee. You can target
the swivel angle to an another object to animate it. IK Limb Solver also
3384 | Chapter 15 Animation