2009

uses a preferred angle to define a direction for rotation, so the elbow or
knees bend correctly. It also allows you to switch between IK and FK by
keyframing IK Enabling, and it has a special IK for FK pose function so you
can use IK to set FK keys.
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Spline IK Solver on page 3445
The Spline IK solver uses a spline to determine the curvature of a series of
bones or other linked objects.
Vertices on a Spline IK spline are called nodes. Like vertices, the nodes can
be moved and animated to change the curvature of the spline.
The number of spline nodes can be fewer than the number of bones. This
provides the ease of posing or animating a long multiple-bone structure
with just a few nodes, as opposed to animating each bone individually.
Spline IK provides a more flexible animation system than other IK solvers.
Nodes can be moved anywhere in 3D space, so the linked structure can be
intricately shaped.
A helper object is automatically placed at each node when Spline IK is
assigned. Each node is linked to its corresponding helper, so a node can
be moved by moving the helper. Unlike the HI Solver, the Spline IK system
does not use a goal. The positions of nodes in 3D space is the only factor
that determines the shape of the linked structure. Rotating or scaling nodes
has no effect on the spline or structure.
NOTE 3ds Max also provides two other methods of inverse kinematic manipulation
of hierarchies, which don't depend on a solver:
Interactive IK on page 3459 and
Applied IK on page 3462.
IK with Bones
While you can apply an IK solver to any hierarchy of objects, a system of
Bones on page 901 combined with an IK solver is a good way to animate a
character.
A bones system is a jointed, hierarchical linkage of bone objects. Bones are
used as an armature on to which objects are linked. If you use the
skin modifier
on page 1672, you can "skin" an object to the bones, so the animation of the
bones deforms the mesh that models a character. If you have a jointed
character, you can use linkage or constraints so the bones animate the mesh.
Inverse Kinematics (IK) | 3385