Constraint

Any entity that constrains one or more physically simulated entities (such as func_physbox or prop_physics) to each other.

Below is a (so far incomplete and somewhat unconfirmed) list of all contraints:

Basic constraints

• phys_constraint constrains distance and rotation.
• phys_lengthconstraint constrains distance only.
• phys_keepupright constrains rotation only.

Specified constraints

• phys_ballsocket constrains distance to the origin specified.
• phys_hinge constrains distance and rotation to the axis specified.
• phys_slideconstraint constrains movement to the axis specified.

Complex constraints

• phys_pulleyconstraint
• phys_ragdollconstraint
• phys_spring constrains length and rotation like a spring.

• phys_constraintsystem is used to manage a group of interacting constraints and keep them stable.