Constraints (also known as joints) for rigid bodies connect two rigid bodies.
The physics constraints are meant to be attached to an Empty object. The constraint then has fields which can be pointed at the two physics-enabled object which will be bound by the constraint. The Empty object provides a location and axis for the constraint distinct from the two constrained objects. The location of the entity hosting the physics constraint marks a location and set of axes on each of the two constrained objects. These two anchor points are calculated at the beginning of the animation and their position and orientation remain fixed in the local coordinate system of the object for the duration of the animation. The objects can move far from the constraint object, but the constraint anchor moves with the object. If this feature seems limiting, consider using multiple objects with a non-physics Child of constraint and animate the relative location of the child.
The quickest way to constrain two objects is to select both and click the Connect button in :menuselect:`Object --> Rigid Body`. This creates a new Empty object (named "Constraint") with a physics constraint already attached and pointing at the two selected objects.
Rigid Body Constraint panel.
- Specifies whether the constraint is active during the simulation.
- Disable Collisions
- Allows constrained objects to pass through one another.
- Object 1
- First object to be constrained.
- Object 2
- Second object to be constrained.
Allows constraint to break during simulation. Disabled for the Motor constraint. This can be used to simulate destruction.
- Impulse strength that needs to be reached before constraint breaks.
- Override Iterations
Allows to make constraints stronger (more iterations) or weaker (less iterations) than specified in the rigid body world.
- Number of constraint solver iterations made per simulation step for this constraint.
- By using limits you can constrain objects even more by specifying a translation/rotation range on/around respectively one axis (see below for each one individually). To lock one axis, set both limits to 0.