Edit constraints

After you create a constraint, Maya creates a constraint named for the type of constraint. For example, rigidNailConstraint1 is the default name given to a Nail constraint. To adjust a constraint’s attributes in the Attribute Editor, you must first select the constraint in the Outliner or the constraint icon in the workspace.

NoteThe Rigid Constraint Attributes section of the Attribute Editor displays read-only Force and Solver Id attributes. The Force shows the X, Y, and Z components of the current force pulling towards one or both objects connected to the constraint. The Solver Id is the constraint index number the solver uses to calculate dynamics for this constraint. You can query the value of these attributes in expressions and MEL commands.

Adjust the initial position and orientation

You can adjust the initial position of all rigid body constraints. You can adjust the initial orientation of only Hinge and Barrier constraints.

To adjust a constraint’s position

Do one of the following:
- Use the Move tool to drag the constraint icon.
- In the Rigid Constraint Attributes section of the Attribute Editor, enter X, Y, and Z values for Initial Position.
  TipIf you move a constraint in a frame other than the starting frame, rewind to make the constraint animate properly.

To adjust a Hinge or Barrier constraint’s initial orientation:

Do one of the following
- Use the Rotate tool to rotate the initial orientation icon.
- In the Rigid Constraint Attributes section of the Attribute Editor, enter X, Y, and Z values for Initial Orientation.

Change or turning off the constraint type

You can change the constraint type or turn a constraint off or on after you create it. Before you change the constraint type, be aware of these issues:

You cannot change a single-body constraint to a dual-body constraint.
If you change the constraint type, the constraint name doesn’t change.
A Nail or Barrier constraint cannot constrain a passive rigid body.
You cannot constrain two passive rigid bodies to each other.

To change the constraint type

In the Rigid Constraint Attributes section of the Attribute Editor, select the constraint type from the Constraint Type menu.

To turn a constraint off (or on)

In the Constraint Control section of the Attribute Editor, set these attributes:

Constrain

Turns a constraint on or off.

Relative To

For a constraint between a pair of rigid bodies, this lets you choose where Maya recreates a constraint after you turn it on again. Your choices follow:

Body 1

Recreates the constraint at the original distance and orientation from the first of the two rigid bodies you selected when you created the constraint.

Body 2

Recreates the constraint at the original distance and orientation from the second of the two rigid bodies you selected when you created the constraint.

Mid Point

Recreates the constraint at the midpoint between the two rigid bodies.

User Defined

Lets you specify the position in the User Defined Position X, Y, and Z boxes. These attributes are dim unless you turn on User Defined.

Example

Suppose you create a pin constraint between two objects. The pin is positioned as follows. The small square represents the pin’s location.

Before making the pin constraint, the sphere was selected first and the cylinder second. In the context of the Relative To attribute, the sphere is therefore Body 1 and the cylinder is Body 2.

You then animate the movement of the cylinder in a direction perpendicular to the constraint line icon. The constraint forces the sphere to swing around the cylinder. If you key Constrain off for several frames, the sphere is no longer constrained to the cylinder. It moves in its own direction using the force previously applied to it by the constraint.

When you key Constrain on again in a later frame, the sphere will once again be tied to the cylinder. You can set the location and orientation of the pin by setting the Relative To attribute. This influences how the objects interact with each other’s movement.