Character Animation: The Fun Part - Blender Foundations: The Essential Guide to Learning Blender 2.6 - page 324

And now everything's cool until we get to the end, where he
actually has to throw the cube. Can you figure out how to
release to cube from his hand? We've not done this exactly, but
we've accomplished something much like it already. First, find
the frame on which you want the cube to come free. Select the
cube itself and press the I key to bring up the keyframing menu.
Notice the three keying options at the bottom that all begin
with Visual ? Ordinarily, objects that are under constraints don't
actually “know” where they are. They display correctly, but if
you were to add a location keyframe to them, it would key
from the unconstrained position. Choosing one of the Visual
keying options tells the object to actually take a look around
and figure out where it really is. So on this frame, set a Visual-
LocRot key, which will record the actual location and rotation
of the cube in its constrained state.

Step back one frame and use the RMB > Insert Keyframe
method to insert keys on the Influence property of each of the
cube's constraints. Step forward again, set both Influence values
to 0.0, and make sure to key them.

What you've done is record the constrained transformation of
an object, but turn the constraints off. On that frame, it will
appear exactly as though it is still constrained, although it no
longer is. And from that point, you're free to animate it any
way you like. You can see from the finished product that I
chose to have the cube tumble through the air, then bounce to
a stop on the tabletop.

Figure 11.40 Add both Copy Location and
Copy Rotation constraints to the cube, targeting
the new bone in the armature.

Checking Your Arcs
As a final step in refining your animation, you should check your arcs. Being creatures whose limbs gener-
ally rotate around pivots of one kind or another, our natural motion tends to create arcs. For our animation
to look believable, it should too. Figure 11.41 shows the complete paths taken by both of the character's
hand bones throughout the animation.

A path for any bone can be calculated and displayed by selecting the bone and choosing Motion Paths
> Calculate from the Pose menu on the header. They can be removed by choosing Clear from the same
submenu. The purpose of displaying these paths is to make sure that your character's limbs aren't moving
in a jerky, robotlike fashion. It appears for the example file that things aren't too bad. The straight lines
you see represent the very fast motion of both the wave and the throw. If there were more frames between
those key points, the curve would look smoother.