Position Constraints

You can constrain one or more objects to the position (location) of another object. The Position constraint constrains an object's center to the constraining object's center, moving the constrained object to that location.

This can be any kind of object that has a center, including all standard geometric objects as well as nulls, lights, cameras, and lattices. For a character, you could use position constraints to constrain an effector to its root, such as a leg's effector to a foot's root.

Because this constraint puts the objects directly "on top" of each other, you usually need to offset the constrained object, either in the constraint's property editor (see below) or with constraint compensation (see Setting Offsets with Compensation).

To constrain an object's position

Select the object to be constrained.
Choose Constrain Position and pick the object to act as the constraining force.

The constrained object's center is repositioned to the center of the constraining object.

In the Position constraint property editor, you can set an offset between the centers of the constrained and constraining objects by entering values for the X, Y, Z sliders for either of them.

See Creating Offsets between Constrained and Constraining Objects for more information about offsets.

A	Enter the XYZ axis offset of the constraining object's center in the Constraining Object axis controls.
B	The position constraint is calculated according to the constraining object's center, which is offset on the X axis by 1. (An offset has already been applied to the position of the constrained object's center.)
C	If Affected by Orientation is selected for the Constrained Object, the airplane is influenced by the orientation (rotation) of the magnet.

You can also select Affected by Orientation for either the constrained or constraining object. If you do so, the object rotation is included as part of the constraint for that object.

For example, if you select Affected by Orientation for the constrained object, its position is affected by the orientation of the constraining object.

The Affected by Scaling option operates in a similar manner for scaling.
When you transform the constraining object, the constrained object's center remains aligned to it.

Pinning an Object in Position

Instead of having to create an object and then set up a position constraint between it and the object you want to constrain, you can easily pin an object in place with just one command.

To pin an object

Select the object you want to pin.
Choose Constrain Pin Object into Position.

This creates a "pinning" object in the form of a small implicit sphere (called TEMP_PIN) in the location of the selected object. The selected object is then position-constrained to the pin object.

To undo the pinning

Select the constrained object and choose Constrain Pin Object into Position again to deactivate it.

This deletes the TEMP_PIN object and removes the position constraint.

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