2010

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to a value of 1. If you move the mechanical arm, the cargo box will move
somewhere between its first and second position. This occurs because
each constraint has equal influence on the cargo box at this point.
Before you can animate the objects in the scene, you also need to reset the
default weight values for each constraint, so that one parent constraint has
full influence on CargoBox when the other does not.
To set the weighting for the parent constraints
1 In the Hypergraph, select only CargoBox.
2 In the Channel Box, set the following:
Platform W1: 0
3 Select only SwivelBase.
4 In the Channel Box, set the Rotate Y value to 0.
The mechanical arm and cargo box are rotated back.
5 In the Hypergraph, select only CargoBox.
6 In the main menu, select Constrain > Set Rest Position.
Setting a rest position for CargoBox sets a position for the cargo box when
no constraints are acting upon it. If the rest position is not set, CargoBox
will be repositioned to the second constraint position.
7 In the Channel Box, set the following:
ArmControl W0: 0
At this point, both parent constraints are set to have no influence on the
cargo box because their weight attributes are set to zero. When you
animate the components in the scene, the weight attributes for the parent
constraints will be set and keyframed depending on which constraining
object (Arm or Platform) is required to have full influence.
In the next steps, you plan the action for animation of the IK system.
Planning an animation for an IK system
Now that the mechanical arm and cargo box are fully set up for animation
its a simple matter to pose the arm and set keyframes. Prior to setting any
keyframes you should take a few moments to plan the action for the scene.
308 | Chapter 6 Animation