Offset constraints keep an offset between the driver and driven controls. In this example, we constrain a guitar (driven) to Electra’s cog (driver). We start with a scene that contains animation only on Electra:

1. In the animate state, bring up the parameters HUD (press G over the viewport).

2. In the Constraint tab, set Constraint to Offset.

3. Select the guitar’s control.

   Note

   The two parameters below the Constraint parameter show the order in which to select the controls. For offset constraints, select the driven control, then the driver. If you select more than two controls before pressing H, the last selected control is the driver, and all the other controls are driven controls.

4. Hold ⇧ Shift and select Electra’s cog control.

5. Hover over the viewport and press H. A constraint is added and the driven control turns gray. A dotted line appears with an arrow pointing from the driver to the driven control, and you will not be able to move the guitar control because it is now constrained to Electra’s cog.

   

6. We want to constrain Electra’s left hand to the neck of the guitar. To do this, first create a locator on the neck of the guitar:

   • Enter the locator tool.

   • Press H over the viewport to create the locator.

   • Position the locator at the neck of the guitar.

     Note

     If you are working with animation layers, the locator needs to be added to the current layer before you can move it. Select the locator, go to the animation layers pane, click the layer, and select Add Selected Controls to Layer.

   • Exit the locator tool.

   

7. Constrain the locator to the guitar so that as the guitar moves, the locator stays at the neck of the guitar. Select the locator, hold ⇧ Shift, select the guitar control, and press H over the viewport.

   

8. Constrain Electra’s hand to the locator - select Electra’s hand, hold ⇧ Shift, select the locator, and press H over the viewport.

9. Rotate Electra by setting keys on her cog control.

   Note

   If you are working with animation layers, the cog control needs to be added to the current layer before you can set keys on it.

10. The strumming hand doesn’t follow the guitar after rotating Electra, so constrain Electra’s hand to the guitar control with a parent constraint. This way, as the guitar (driver parent) moves, Electra’s strumming hand (driven child) moves with it:

    • Select Electra’s right hand control.

    • Hold ⇧ Shift and select the guitar control.

    • In the parameters HUD, Constraint tab, set Offset to Parent.

    • Press H over the viewport.

We now have the following constraints added to the scene:

• The guitar is constrained to Electra’s cog.

• The locator on the neck of the guitar is constrained to the guitar.

• Electra’s left hand is constrained to the locator.

• Electra’s strumming hand is constrained to the guitar.

  

Animate the offset between the driver and driven controls ¶

When you create an offset constraint, a control named <control>__Offset is created. This control represents the driven control’s offset from the driver, and it can be animated. The offset control is positioned at the driven control, but is a separate control from the driven control. The offset control is represented as a green sphere:

In this example, we want Electra’s hand to move along the neck of the guitar, so we set keys on the locator offset control (Electra’s hand is constrained to the locator, so moving the locator also moves Electra’s hand).

The locator is constrained to the guitar, so the locator offset control represents the offset between the guitar and the locator. In our example, the locator offset control is named Locator_0__Offset, and it appears in the selection sets under All Controls ▸ constraints ▸ Locator.

1. Select the locator constraint in the selection sets, All Controls ▸ constraints ▸ Locator. Making this selection “focuses” on the constraint so that keys can be set on the constraint’s offset control.

2. Set keys to move the locator offset control up and down the neck of the guitar.

   The animation on the offset control lives on the constraint and not on the locator’s control. Any animation that was originally on the locator is overridden by the constraint. If you turn off the constraint, you are left with the original animation on the locator.

   Note

   If you are working with animation layers, the offset control needs to be added to the current layer before you can set keys on it. In the animation layers pane, click the layer and select Add Selected Controls to Layer.

3. To blend between the offset control animation and the original animation:

   • Select the locator constraint in the selection sets, All Controls ▸ constraints ▸ Locator.

   • In the parameters HUD, Constraint tab, adjust the Blend value.

   Note

   If Blend is set to 0, you can move the driven control.

A lookat constraint allows an object to follow the path of another object. In this example, we add a lookat constraint to keep Electra looking at Flip.

1. Aim Electra’s head toward Flip.

2. Bring up the parameters HUD (press G over the viewport).

3. In the Constraint tab, set Constraint to LookAt.

4. Select Electra’s head control.

   Note

   The two parameters below the Constraint parameter show the order to select the controls. For lookat constraints, select the driven control (Electra’s head), then the target (Flip).

5. Hold ⇧ Shift and select Flip’s control.

6. Hover over the viewport and press H. A constraint is added and the driven control turns gray. A dotted line appears with an arrow pointing from the target to the driven control.

7. A control named <driven_control>__Target is created, and this is the control that the driven object looks at. You can move the control away from the target object, which provides more flexibility on where Electra is looking:

   The <driven_control>__Target control appears in the selection sets under All Controls ▸ constraints. The control is parented to the target object and can be animated.

You can set a control to be driven by multiple drivers using a multidriver constraint. In this example, we constrain Flip to both of Electra’s hands:

1. Bring up the parameters HUD (press G over the viewport).

2. In the Constraint tab, set Constraint to MultiDriver.

3. Select Flip’s control.

   Note

   The two parameters below the Constraint parameter show the order to select the controls. For multidriver constraints, select the driven control (Flip), then the driver controls (Electra’s hands).

4. Hold ⇧ Shift and select Electra’s two hand controls.

5. Hover over the viewport and press H. Constraints are added between Flip and Electra’s hands.

A pin constraint allows you to keep a control at a certain position. A pinned control will not move, even if you move its parent control.

1. Bring up the parameters HUD (press G over the viewport).

2. In the Constraint tab, set Constraint to Pin.

3. Select the control(s) to pin.

4. Hover over the viewport and press H.

A transient constraint is a special type of constraint that is only active within a frame range. Transient constraints differ from regular constraints in the following ways:

• When a transient constraint is created, keyframes are automatically written out for the driven object within the constraint frame range. A bookmark is also created on the playbar timeline to identify the frame range during which the constraint is active.

• The driven object can be moved around freely.

• Transient constraints only apply in the animation layer in which they are created. Regular constraints apply regardless of the layer you're on.

In this example, we transfer the ball from one hand to another. The original animation is shown below:

1. Constrain the ball to the hand:

   • Select the driven control (ball), hold SHIFT, then select the driver (hand).

   • On the timeline, select the range of frames to make the constraint active (hold SHIFT and drag along the timeline).

   • Hover over the viewport and press H.

   A constraint is created between the ball and the hand, and keyframes for the ball are added to every frame in the selected frame range.

   Note

   The constraint behavior is only active within the transient constraint frame range.

   An arrow visualizer shows the constraint relationship between the ball and hand:

   

2. Fix the position of the ball on the hand.

   Once the transient constraint is created, the driven object (ball) can be moved around and the changes are automatically applied to the entire frame range that the transient constraint is active. Make sure you are currently within the frame range that the transient constraint is active, or the changes will not be applied to the entire frame range.

   Note

   If the changes are not applied to the entire transient constraint frame range, make sure that Auto Update Follow Ranges is turned on in the settings HUD, Constraint tab.

3. Constrain the ball to the other hand:

4. Fix the ball on the second hand:

5. Fix the pop on the animation as the ball transitions from one hand to the other:

   • Select the ball (driven object).

   • Click in the timeline so that the current frame is within the frame range of the first transient constraint.

   • In the settings HUD, Constraint tab, click the button. This updates the offset on the ball to match the frame after the current constraint range so that there is a smooth transition between the current range and next range.

6. Fix the hand (driver) in the first constraint range without moving the ball. Select the hand, hold ⇧ Shift + H, and adjust the hand: