Joints

joints

https://docs.coronalabs.com/guide/physics/physicsJoints/index.html

pivot

bodyA

• bounce = 1

• density = 1

• friction = 1

• gravityScale = 1

• isSensor = true

• radius = 0 –0 means use object width/2 if cirlce is selected

• shape =“rectangle”, – “circle”, – rectangle, path

• type = “static” – kinematic, static, dynamic

  

bodyB

• bounce = 1

• density = 1

• friction = 1

• gravityScale = 1

• isSensor = false

• radius = 0, –0 means use object width/2 if cirlce is selected

• shape =“rectangle”, – “circle”, – rectangle, path

• type = “dynamic”, – kinematic, static, dynamic

  

joint A B

- bodyA = "rect_0"
- bodyB = "rect_1"
- type = "pivot", --pistoin, distance, pulle, + defaultSet
- anchor_x = rect_0.x + rect_0.width/2
- anchor_y = rect_0.y + rect_0.height/2
- isMotorEnabled= true
- maxMotorTorque = 1000
- motorForce = 1
- motorSpeed = 10
- isLimitEnabled = false
- rotationX = rect_0.x
- rotationY = rect_0.y

Handoff: Physics Joint Anchors vs Scale (App/physics)

Confirmed Findings

• Solar2D/main.lua currently has env.props.scale = 1.
• If this is changed to 2, then kwikGlobal.scale-based anchor formulas in joint files double their width/height offsets.
• Ellipse/circle objects should use anchorX, anchorY = 0.5, 0.5 for center-based joint anchors.
• Rectangle objects with anchorX, anchorY = 0, 0 are fine as long as joint anchors add width/2 and height/2 (or scaled equivalents).

How Scale=2 Affects Joint Anchor Coordinates

For joints that compute center from top-left anchors using:

obj.x + obj.width * kwikGlobal.scale * 0.5
obj.y + obj.height * kwikGlobal.scale * 0.5

changing env.props.scale from 1 to 2 doubles the local offset term:

• scale=1: obj.x + obj.width * 0.5
• scale=2: obj.x + obj.width * 1.0

So anchor points move farther from the top-left anchor when scale is increased.

For joints using direct center-positioned objects (anchor=0.5,0.5) and anchor_x = ellipse.x, scale does not appear explicitly in the formula.

Joint Anchor Report (All Joint Files in App/physics/components/*/joints)

Anchor Settings of Referenced Objects (Wheel + Gear)

Recommendation

• Keep ellipses/circles at anchorX, anchorY = 0.5, 0.5 (recommended).
• Avoid anchor=0,0 for circles when using center-based wheel/pivot anchors.
• Rectangles with anchor=0,0 are valid and already handled correctly by explicit center offsets in joint formulas.