Precedence

Use the three joint precedence controls to alter how 3DS MAX calculates the IK Solution.

3D Studio MAX uses a default joint precedence of 0. This is suitable for many IK solutions. It assumes that joints closest to where a force is applied (the end effector) will move more than joints farther from the force.

Child>Parent values are calculated by assuming the root of the entire hierarchy has a precedence value of 0 and each child has a value equal to 10 times its depth from the root. In a 4 object hierarchy starting with the root, the values would be 0, 10, 20, 30.

Parent>Child values are calculated by assuming the root of the entire hierarchy has a precedence value of 0 and each child has a value equal to 10 times its depth from the root. In a 4 object hierarchy starting with the root, the values would be 0, -10, -20, -30.

• Default joint precedence occurs whenever all joints in the kinematic chain have the same precedence value. Assigning a value of 100 to all objects in the kinematic chain is exactly the same as assigning a value of 0.
• The precedence calculations only consider the relative IK values. This means that an IK chain of three objects with precedence values of 0, 30, and 200 would have the same solution if the precedence were changed to be 1, 2, and 3.

Reference

There are 3 controls to set precedence:

Precedence: Manually assigns precedence values to any object in the IK chain. High precedence values are calculated before low precedence values. Precedence values that are equal are calculated in Child>Parent order.

Child>Parent: Automatically sets joint precedence to decrease in value from child to parent. Causes joints closest to where a force is applied (the end effector) to move more than joints farther away from the force.

You almost always assign Child>Parent precedence to an entire kinematic chain.

Child>Parent behaves like the default precedence settings but is more flexible if you want to go back and manually change the settings.

Parent>Child: Automatically sets joint precedence to decrease in value from parent to child. Causes joints closest to where a force is applied (the end effector) to move less than joints farther away from the force.

You almost always assign Child>Parent precedence to an entire kinematic chain.

How To

To assign a precedence value to an object manually:

1. Select an object.
2. Open the Object Parameters rollout in the Hierarchy panel.
3. Enter a value in the Precedence field.

To assign Child>Parent precedence to all objects in a kinematic chain:

1. Select all objects in the kinematic chain.
2. Open the Object Parameters rollout in the Hierarchy panel,
3. Click Child>Parent.

To assign Parent>Child precedence to all objects in a kinematic chain:

1. Select all objects in the kinematic chain.
2. Open the Object Parameters rollout in the Hierarchy panel.
3. Click Parent->Child.

To reset the default joint precedence:

1. Select all objects in the kinematic chain.
2. Open the Object Parameters rollout in the Hierarchy panel.
3. Set the value in the Precedence field to 0.