joint2d

2d · physics · 18 properties · 2D

Holds this node's body to another one in 2D: a hinge, a slider, a rope, a spring, or a generic joint you lock axis by axis. Both ends need a body2d.

In a scene, joint2d is the node key that applies it. A script reaches the same properties through node.joint2d.get() and node.joint2d.set(table).

Properties

property	type	default	description
anchor	vec2	[0,0]	Where the joint attaches on this node, in its own space
axis	vec2	[1,0]	The direction a prismatic joint slides along
body	node	—	The node at the joint's other end; this node is the first end
break_force	float	0	The pull that snaps the joint and calls on_joint_break; 0 never breaks At least 0.
contacts	bool	false	Let the two joined bodies collide with each other
damping	float	1	How quickly the motion settles, for a spring joint or a motor At least 0.
enabled	bool	true	Hold the two bodies together at all
kind	enum	fixed	How the two bodies may move relative to each other One of fixed, revolute, prismatic, rope, spring, pin_slot, generic. Scene shorthand: kind's value can be given as the component's whole value.
length	float	0	The rope's greatest length, or the spring's rest length At least 0.
limits	vec2	[0,0]	How far the joint may travel, as a low and a high; equal values mean no limit
locked_axes	flags	[]	Which of the three freedoms a generic joint takes away One of x, y, ang_x.
motor	enum	off	Drive the joint towards a speed, towards a position, or not at all One of off, velocity, position.
motor_max_force	float	0	The most force the motor may use; 0 means as much as it takes At least 0.
motor_model	enum	acceleration	Whether the motor's strength is felt as an acceleration, ignoring mass, or as a force One of acceleration, force.
motor_target	float	0	The speed or the position the motor drives towards
other_anchor	vec2	[0,0]	Where it attaches on the other node, in that node's space
solver	enum	impulse	impulse holds any arrangement, loops included; reduced never drifts and can be solved for inverse kinematics, but cannot close a loop One of impulse, reduced.
stiffness	float	0	Spring stiffness, for a spring joint or a position motor At least 0.

Script functions

Methods of node.joint2d, the handle a node carrying this component exposes. Each is also a free function on its module, taking the node as its first argument. Every handle also has get(), set(table), has() and remove().

From physics2d:

method	what it does
add_joint(any)	Tie this node's body to another with a 2D joint, from a joint2d table.
joint_impulse() -> float	How hard the joint is pulling right now.
remove_joint()	Undo the node's joint, leaving both bodies free.
set_joint_limits(float, float)	Set how far the joint may travel.
set_motor_position(float, float, float)	Drive the joint towards an angle or a distance, with a spring's stiffness and damping.
set_motor_velocity(float, float)	Drive the joint towards a speed: how a wheel is powered.