cast a ray of a given length in a given direction and return the result. null if no hits.
raycast from a physics body in a certain direction, excluding the source body
the total number of bodies in this physics world
the number of dynamic bodies in this physics world
the number of static bodies in this physics world
gravity in the physics world
the maximum number of collisions to support in this world
position correction iterations used by physics engine
velocity correction iterations used by physics engine
represents a manager for physics bodies