Graphics Reference
In-Depth Information
The great thing about using the hotkeys to generate constraints is that the targeting information
is entered for you in the constraints panel, eliminating typos and having to look up object
names. This is especially useful when your target is a bone because you would otherwise have
to type in both the name of the armature and the bone.
Blender also lets you use a different IK mode to generate poses on limbs and structures that are not part of
an actual IK chain. In this mode, the character's bones will move according to IK principles during direct
manipulation and posing. That is where the effect ends, though. Under normal IK conditions, you move and
keyframe only the IK controller bone while the rest of the chain follows it. Interpolations between keyframes
are done on the controller bone, and the IK chain is recalculated for each frame. When using the special
pose-only IK tools, normal keyframes are required on all bones in the chain to record the pose, and interpo-
lation between poses is done based on normal FK rotations—not according to IK rules.
So using the pose-only IK tools, you
get the intuitive posing capabilities
of IK but retain the ability to rotate
and adjust bones within the bone
chain for the fi ne-tuning provided
with FK. Figure 9.14 shows two
bones chains. The one on the left is
rigged with standard IK; the one on
the right, pose-only IK. Rotating the
middle bone in the chain has little
to no useful effect on the IK chain,
while it produces the standard rota-
tion behavior on the other chain.
90°
90°
In Blender, this pose-only type of
constraint is called Targetless IK . An
IK constraint is applied to a bone,
but a target is not assigned. If you
add the IK constraint from the
Constraints panel in the Edit but-
tons , making it targetless is as simple as not entering a target. The constraint name fi eld becomes red, and
the bone itself becomes orange (normal IK constrained bones are yellow). If you are using the Ctrl-I hotkey
to create the IK chain, select only the bone (remember, you're going for “targetless” IK, so you don't need to
select a target bone) and choose Without Target from the pop-up menu. Figure 9.15 shows both the pop-
up menu and the constraints panel for targetless IK.
Figure 9.14 The difference in rotating bones in the middle of different kinds of
bone chains
 
Search WWH ::




Custom Search