Graphics Programs Reference
In-Depth Information
Creating an IK Walk Cycle
Because the block man's feet will stick to the ground, creating a walk cycle with IK ani-
mation is far easier than using FK. Making the animation look good is still a tough job
that requires a lot of practice.
Load the scene file
block_man_IK_v01.mb
from the Block_Man project on the CD, or use
your own IK-rigged block man with handles at the ankles and feet. The white leg and arm
are again on the far side of the character. You'll set keys every five frames again for the
gross animation. To keep this short, we'll just discuss setting poses with the feet. You can
always return to the scene to add animation to the upper body with FK, as you did earlier
in this chapter. Follow these steps:
1. On frame 1, set translate keys on the pelvis joint and all four IK handles for their
start position.
2. Go to frame 5, and move the pelvis forward about 1 unit. The legs and feet lift off the
ground a bit and strain to keep their position. Lower the pelvis to get the feet f lat on
the ground again. Set a key for the pelvis.
Because Auto Keyframe is turned on, all
keys are set for this animation. (With the
FK animation, you set keys for everything
at every pose.)
3. Grab the near IK handles for the ankle and
foot, and move them forward and up to
match the pose shown in Figure 9.46.
4. Go to frame 10. Move the front foot for-
ward, and plant it on the ground. Move
the pelvis another three-fourths of a unit.
Set translation keys for the rear ankle and
foot handles where they are. Be sure to place
the pelvis so that the rear foot is almost
f flat on the ground. Match the pose shown
in Figure 9.47.
5. Go to frame 15. Move the pelvis another
2 units to center the body over the front
foot. Lift the rear ankle and foot IK handles up to bend the knee, and bring the knee
up a bit. Match the pose shown in Figure 9.48.
6. Go to frame 20. Move the pelvis forward 1 unit, and swing the white leg forward as
in the pose shown in Figure 9.49.
7. Move the pelvis three-fourths of a unit forward, and plant the front leg down. Set
keys for the rear leg and foot where they stand. Match the pose shown in Figure 9.50.
Figure 9.46
Step 3's pose
