Constraints

Constraints restrict rigidbodies to certain movement patterns. For example, a realistic knee joint can only move along one axis and can't bend forwards.

Constraints can either link two rigidbodies together, or link a single rigidbody to a point in the world. They allow for interaction and dependency among rigidbodies.

There are six types of constraints:

• gears
• sliders
• cones (twist and turn)
• point to point (fixed distance between two colliders)
• six degrees of freedomFor a demonstration of the different constraints, load the PhysicsSample sample project.

Note

To create a constraint, use the Simulation static method :

This links RigidBodyA to the world at its current location.The boolean specifies which coordinate system the limit is applied to (either RigidBodyA or the world).

Note

• In the case of ConstraintTypes.Point2Point, the frame represents a pivot in A. Only the translation vector is considered. is ignored.
• In the case of ConstraintTypes.ConeTwist, is ignored.
• ConstraintTypes.Gear needs two rigidbodies to be created. This function will throw an exception.

This method links to RigidBodyB.

Note

• In the case of ConstraintTypes.Point2Point, the frame represents a pivot in A or B. Only the translation vector is considered. is ignored.
• In the case of ConstraintTypes.Hinge the frame represents pivot in A/B and Axis in A/B. This is because the hinge allows only a limited angle of rotation between the rigidbody and the world in this case.
• In the case of , useReferenceFrameA is ignored.
• In the case of , useReferenceFrameA is ignored. The frame just represents the axis either in A or B; only the translation vector (which should contain the axis) is used.

After you create a constraint, add it to the simulation from a script by calling:

or:

The parameter stops linked bodies colliding with each other.