Distance Joint 2D fundamentals

The main application of the Distance Joint 2D component is to keep distance between two points. These two points can be two Rigidbody 2D components or a Rigidbody 2D component and a fixed position in the world.

Note: To connect a Rigidbody 2D component to a fixed position in the world, set the Connected Rigidbody field to None.

This Joint 2D does not apply torque or rotation. It does apply a linear force to both connected items, using a very stiff simulated ‘spring’ to maintain the distance. You cannot configure the properties of this ‘spring’.

This Joint 2D has a selectable constraint:

• Constraint A: Maintains a fixed distance between two anchor points on two bodies (when Max Distance Only is unchecked).
• Constraint B: Maintains maximum distance only between two anchor points on two bodies (when Max Distance Only is checked).

You can use this Joint 2D to construct physical objects that need to behave as if they are connected with a rigid connection that can rotate.

• Using Constraint A (Max Distance Only unchecked), you can create a fixed length connection, such as two wheels on a bicycle.
• Using Constraint B (Max Distance Only checked), you can create a constrained but unfixed length connection, which allows flexible movement such as a yo-yo moving towards and away from a fixed point.

Additional resources

• Joints 2D
• Distance Joint 2D component reference