Constrains in Animation
1. What are the constraints
Constraints can help us constrain the position, orientation, or scale of an object to other objects. Further, with constraints we can impose specific limits on objects and automate animation processes.
2. Different sorts of constraints
Point: If you want to control the displacement of object B with object A, you can use Point constraint. After the Point Constraint, you will see that A will move to the middle of B. (If you don’t want the objects to coincide, choose Maintain Offset in the Point Constraint Options). (If you don’t want the objects to overlap, select Maintain Offset in Point Constraint Options) When you move A, you’ll see that B follows A. When you select B, you’ll see the properties on the right side. When you select B object, you can see that all the Translate XYZ in the right property bar are blue constrained. In the constrained state, there is no Keyframe creation for the B object.
Aim: This is a constraint on the direction of the target object. After the Aim constraint (choose Maintain Offset), you will see that when you move A, the B direction will follow A. The B direction will only have an effect on the Translate, not the Rotate. (Personally, I feel like a person’s eyeballs move with the visual focus.)
Orient: control the rotation of the object. After the Orient constraint (Maintain Offset), the direction of B will only have an effect when Rotate is selected, not when Translate is selected.
Parent: Translate + Rotate constraint. After Parent, you can use A to control B’s Translate and Rotate.
Scale: control the zoom in and zoom out of the object. First, choose A, then choose B. After Scale constraint (choose to Maintain Offset), you can use A’s Scale to control B’s Scale.
To remove the constraint, delete the constraint node from the outline property bar. Or you can select “constraint” in “Delete by Type” under “Edit”.
3. What do we use constraints for and how can they help us animate
When we animate character that we often have some items that need to be added to character, such as swords, crowns, etc. When the character moves, we need to make sure items move with the character. If we don’t use Constraints, we may need to animate the item movement at each keyframe. This method will add lots of work. So constraints help us save the hassle in creation process.
4. Parenting VS parent constraint
Parenting is easy for just making something move with something else, but you can still animate the object that is a child freely.
Parent constraining will move one object with another like normal parenting, but it will lock the child’s translations, so that child through the constraint will move in world space or whatever space it is in relative to its parent’s movements.
Parent constraint can return values to control other objects that would otherwise be difficult to find without the parent constraint.