Constraints (Alpha)

A constraint is an entity that binds several objects in the scene, allowing one of them to control the positions of the other. Such a feature can be especially useful when you are creating animations that involve additional objects such as tools or weapons.

There is a total of three types of constraints:

Constrain additional is used for binding several Additional Point Controllers to each other.
Constrain points attaches selected Point Controllers to a transform object (i.e. an object that has position, rotation and scale parameters): a joint, a mesh, a locator, or a group.
Constrain transform binds one transform object to another.

Here, we’ll be taking a look at each one of these constraints, how they are applied and purposes they are used for.

Constrain Points

If you’d like to attach one or more Point Controllers to a transform object, use this option.

1. Select Point Controller(s)
2. Select a transform object.
3. Select Rig additional → Constrain points from the Commands menu:

Now, the constraint should be created. However, it won’t have any effect by default. To use the newly created constraint, you’ll have to enable it.

If you select a constrained point, you’ll see a new behavior in the Outliner:

This Constraint behavior, as its name suggests, controls the newly created constraint. There is a total of three options:

Constraint active
When this option is enabled, the constraint is applied to the constrained object; otherwise, it is ignored.
This option can be animated i.e. enabled or disabled individually for each frame. This way, it is possible to manually set parts of the animation where the constraint should or shouldn’t work.
By default, it is enabled for the entire Timeline.

Constraint is enabled
If this is enabled, the constraint is applied to the constrained object.
This parameter should be activated for the constraint to work (whether or not it is actually taken into account is determined by the Constraint active parameter described above).

Constraint enabled on frame
When this parameter is enabled, the constraint will be active during posing (normally, constraints are only active when the animation is played).

To activate the constraint:

1. Turn on the Constraint is enabled option first.

2. On the Timeline, select an interval to which you’d like to apply the constraint.

3. Enable the Constraint active parameter.

Constrain Transform

For the cases when you need to associate objects that are not Point Controllers, you should use this option:

1. Select both objects

2. Select Rig additional → Constrain transform from the Commands menu:

3. The Transform window will appear:

4. In this window, set the ‘main’ object. it will control the other object.

Now, each one of the objects should have a Constraint behavior attached to it. This one is a little different from the behavior used with Point Controllers:

Constraint active
Same as in the behavior for Point Controllers (see above).

Constraint enabled on frame
Same as in the behavior for Point Controllers (see above).

Constraint rotation
This option defines how the rotation of the constrained object is affected when the object it is constrained to is rotated.

There are three possible values.

Compensate means the position of the constrained object is affected by the rotation of the object it is constrained to, but its global rotation is not affected:

Full means rotation is copied completely:

Off means rotation is not taken into account:

Constrain position
If this is enabled, the constrained object’s position is affected when the object it is constrained to is moving.

Just like in the previous case, these constraints can be switched on and off individually for each frame and interval

Constrain Additional

Finally, there is a way to link one part of the rig to another.
This option is useful for constraining long body parts: spines, tails and such.

1. Select several Additional Controllers.
You’ll need at least 3 consecutive Additional Points (the Rigid Bodies associated with these points should form a chain).

2. Select Rig additionals → Constrain additional from the Commands menu:

3. After this, the constraint should be created. Enable it the usual way, and everything should work as intended.

Example

The video below shows how constraints can be used to improve animation: