Joint

Connects two bodies: hinge (revolute), distance, slider (prismatic), weld, wheel or motor; motors, springs and limits. Pick Body A (default: parent) and Body B.

Type: JointNode · Category: Physics & Collision · Also found as: joint, physicsjoint

Properties

Property	Type	Default	Description
`joint.type`	enum: `Distance`, `Filter`, `Motor`, `Mouse`, `Prismatic`, `Revolute`, `Weld`, `Wheel`	`Revolute`	Kind of joint; only that kind’s settings are shown.
`joint.distance.localAnchorA`	vec2	`(0, 0)`	Anchor on body A, relative to its origin (px). Range -500 to 500.
`joint.distance.localAnchorB`	vec2	`(0, 0)`	Anchor on body B, relative to its origin (px). Range -500 to 500.
`joint.distance.length`	number	`100`	Rest distance between the anchors (px). Range 1 to 1000.
`joint.distance.enableSpring`	boolean	`false`	Make the joint springy instead of rigid.
`joint.distance.hertz`	number	`4`	Spring stiffness as an oscillation frequency (Hz); 0 = no spring. Range 0 to 60.
`joint.distance.dampingRatio`	number	`0.5`	Spring damping: 0 bounces forever, 1 settles without overshoot. Range 0 to 10.
`joint.distance.enableLimit`	boolean	`false`	Clamp the joint’s travel to the lower / upper limits.
`joint.distance.minLength`	number	`20`	Shortest the joint may get (px; with the limit on). Range 0 to 1000.
`joint.distance.maxLength`	number	`200`	Longest the joint may get (px; with the limit on). Range 1 to 1000.
`joint.distance.enableMotor`	boolean	`false`	Drive the joint at Motor Speed, up to the maximum force / torque.
`joint.distance.maxMotorForce`	number	`100000`	Strongest push the motor applies (pixel-scale bodies are heavy: mass ~ area in px²). Range 0 to 1e+08.
`joint.distance.motorSpeed`	number	`0`	Speed the motor lengthens (+) or shortens (-) the joint (px/s). Range -500 to 500.
`joint.distance.collideConnected`	boolean	`false`	Let the two connected bodies collide with each other.
`joint.motor.linearOffset`	vec2	`(0, 0)`	Where body B is driven to, relative to body A (px). Range -500 to 500.
`joint.motor.angularOffset`	number	`0`	Angle body B is driven to, relative to body A (degrees). Range 0 to 360.
`joint.motor.maxForce`	number	`100000`	Strongest pull towards the offset (pixel-scale bodies are heavy). Range 0 to 1e+08.
`joint.motor.maxTorque`	number	`5000000`	Strongest twist towards the angle (pixel-scale bodies are heavy). Range 0 to 1e+08.
`joint.motor.correctionFactor`	number	`0.3`	How quickly position errors are corrected (0-1). Range 0 to 1.
`joint.motor.collideConnected`	boolean	`false`	Let the two connected bodies collide with each other.
`joint.mouse.target`	vec2	`(0, 0)`	World point the body is pulled to (px). Range 0 to 1280.
`joint.mouse.hertz`	number	`4`	Stiffness of the pull (Hz). Range 0.1 to 60.
`joint.mouse.dampingRatio`	number	`1`	Damping of the pull: 1 = no overshoot. Range 0 to 10.
`joint.mouse.maxForce`	number	`1000`	Strongest pull applied. Range 0 to 50000.
`joint.mouse.collideConnected`	boolean	`false`	Let the two connected bodies collide with each other.
`joint.prismatic.localAnchorA`	vec2	`(0, 0)`	Anchor on body A, relative to its origin (px). Range -500 to 500.
`joint.prismatic.localAnchorB`	vec2	`(0, 0)`	Anchor on body B, relative to its origin (px). Range -500 to 500.
`joint.prismatic.localAxisA`	vec2	`(1, 0)`	Direction body B slides along, in body A’s space. Range -1 to 1.
`joint.prismatic.referenceAngle`	number	`0`	Body B’s angle relative to body A that counts as zero (degrees). Range 0 to 360.
`joint.prismatic.targetTranslation`	number	`0`	Position the spring pulls to along the axis (px). Range -500 to 500.
`joint.prismatic.enableSpring`	boolean	`false`	Make the joint springy instead of rigid.
`joint.prismatic.hertz`	number	`4`	Spring stiffness as an oscillation frequency (Hz); 0 = no spring. Range 0 to 60.
`joint.prismatic.dampingRatio`	number	`0.5`	Spring damping: 0 bounces forever, 1 settles without overshoot. Range 0 to 10.
`joint.prismatic.enableLimit`	boolean	`false`	Clamp the joint’s travel to the lower / upper limits.
`joint.prismatic.lowerTranslation`	number	`-100`	Furthest back along the axis (px; with the limit on). Range -500 to 500.
`joint.prismatic.upperTranslation`	number	`100`	Furthest forward along the axis (px; with the limit on). Range -500 to 500.
`joint.prismatic.enableMotor`	boolean	`false`	Drive the joint at Motor Speed, up to the maximum force / torque.
`joint.prismatic.maxMotorForce`	number	`100000`	Strongest push the motor applies (pixel-scale bodies are heavy). Range 0 to 1e+08.
`joint.prismatic.motorSpeed`	number	`0`	Sliding speed the motor drives (px/s). Range -500 to 500.
`joint.prismatic.collideConnected`	boolean	`false`	Let the two connected bodies collide with each other.
`joint.revolute.localAnchorA`	vec2	`(0, 0)`	Anchor on body A, relative to its origin (px). Range -500 to 500.
`joint.revolute.localAnchorB`	vec2	`(0, 0)`	Anchor on body B, relative to its origin (px). Range -500 to 500.
`joint.revolute.referenceAngle`	number	`0`	Body B’s angle relative to body A that counts as zero (degrees). Range 0 to 360.
`joint.revolute.targetAngle`	number	`0`	Angle the spring pulls to (degrees). Range -360 to 360.
`joint.revolute.enableSpring`	boolean	`false`	Make the joint springy instead of rigid.
`joint.revolute.hertz`	number	`4`	Spring stiffness as an oscillation frequency (Hz); 0 = no spring. Range 0 to 60.
`joint.revolute.dampingRatio`	number	`0.5`	Spring damping: 0 bounces forever, 1 settles without overshoot. Range 0 to 10.
`joint.revolute.enableLimit`	boolean	`false`	Clamp the joint’s travel to the lower / upper limits.
`joint.revolute.lowerAngle`	number	`-45`	Smallest angle (degrees; with the limit on). Range -360 to 360.
`joint.revolute.upperAngle`	number	`45`	Largest angle (degrees; with the limit on). Range -360 to 360.
`joint.revolute.enableMotor`	boolean	`false`	Drive the joint at Motor Speed, up to the maximum force / torque.
`joint.revolute.maxMotorTorque`	number	`5000000`	Strongest twist the motor applies (pixel-scale bodies are heavy). Range 0 to 1e+08.
`joint.revolute.motorSpeed`	number	`0`	Spin speed the motor drives (radians/s). Range -50 to 50.
`joint.revolute.collideConnected`	boolean	`false`	Let the two connected bodies collide with each other.
`joint.weld.localAnchorA`	vec2	`(0, 0)`	Anchor on body A, relative to its origin (px). Range -500 to 500.
`joint.weld.localAnchorB`	vec2	`(0, 0)`	Anchor on body B, relative to its origin (px). Range -500 to 500.
`joint.weld.referenceAngle`	number	`0`	Body B’s angle relative to body A that counts as zero (degrees). Range 0 to 360.
`joint.weld.linearHertz`	number	`0`	Positional softness (Hz); 0 = rigid. Range 0 to 60.
`joint.weld.angularHertz`	number	`0`	Angular softness (Hz); 0 = rigid. Range 0 to 60.
`joint.weld.linearDampingRatio`	number	`0`	Damping of the positional softness. Range 0 to 10.
`joint.weld.angularDampingRatio`	number	`0`	Damping of the angular softness. Range 0 to 10.
`joint.weld.collideConnected`	boolean	`false`	Let the two connected bodies collide with each other.
`joint.wheel.localAnchorA`	vec2	`(0, 0)`	Anchor on body A, relative to its origin (px). Range -500 to 500.
`joint.wheel.localAnchorB`	vec2	`(0, 0)`	Anchor on body B, relative to its origin (px). Range -500 to 500.
`joint.wheel.localAxisA`	vec2	`(0, 1)`	Suspension direction, in body A’s space. Range -1 to 1.
`joint.wheel.enableSpring`	boolean	`true`	Springy suspension along the axis.
`joint.wheel.hertz`	number	`1`	Spring stiffness as an oscillation frequency (Hz); 0 = no spring. Range 0 to 60.
`joint.wheel.dampingRatio`	number	`0.7`	Spring damping: 0 bounces forever, 1 settles without overshoot. Range 0 to 10.
`joint.wheel.enableLimit`	boolean	`false`	Clamp the joint’s travel to the lower / upper limits.
`joint.wheel.lowerTranslation`	number	`-50`	Suspension’s lowest travel (px; with the limit on). Range -500 to 500.
`joint.wheel.upperTranslation`	number	`50`	Suspension’s highest travel (px; with the limit on). Range -500 to 500.
`joint.wheel.enableMotor`	boolean	`false`	Drive the joint at Motor Speed, up to the maximum force / torque.
`joint.wheel.maxMotorTorque`	number	`5000000`	Strongest twist the wheel motor applies (pixel-scale bodies are heavy). Range 0 to 1e+08.
`joint.wheel.motorSpeed`	number	`0`	Wheel spin speed the motor drives (radians/s). Range -50 to 50.
`joint.wheel.collideConnected`	boolean	`false`	Let the two connected bodies collide with each other.
`debugColor`	color	`#facc15ff`	Colour of the line drawn between the anchors.

Plus the common properties every node has.

Lua methods

Call them on the node (self.node in its script, or self.node:get_node("path")). Every node also has the Node methods.

JointNode:get_property(path)

Reads an Inspector property by its path (vectors and colours as tables); “script.” reads a field of the node’s script.

local value = self.node:get_property("debugColor")

path JointNodeProperty|string

Returns any

JointNode:set_property(path, value, y)

Sets an Inspector property by its path: vectors as {x, y} or x, y; colours as {r, g, b[, a]} 0..1 or “#rrggbb[aa]”; enums by name; “script.” a field of the node’s script.

self.node:set_property("debugColor", "#ff8800")

path JointNodeProperty|string
value any
y? number

In a scene file

{
  "type": "JointNode",
  "name": "Joint",
  "position": [
    0,
    0
  ],
  "properties": {
    "debugColor": "#facc15ff"
  }
}