Damped Track Constraint
The Damped Track constraint constrains one local axis of the owner to always point towards Target. This constraint uses a pure Swing rotation, i.e. the shortest possible single axis rotation. In other 3D software you can find it with the name "Look at" constraint.
Although usually associated with bones, Damped Track can align objects to point to (and follow) other objects or bones. It is important to note that the constraint aligns the origin's axes to point to the target's origin point. This is illustrated in the following figure. In each case the objects are set as Damped Track to +X.
- Track Axis
Once the owner object has had a Damped Track constraint applied to it, you must then choose which axis of the object you want to point at the Target object. The negative axis direction cause the object to point away from the Target object along the selected axis direction.
-X, -Y, -Z, X, Y, Z
Controls the percentage of affect the constraint has on the object. See common constraint properties for more information.