已将SpriteKit节点angularDamping设为0仍存在角阻尼问题

你的单摆会逐渐减速停止，核心是只处理了角阻尼参数，漏掉了两个关键设置：

• 摆球的**线性阻尼（linearDamping）**默认不为0，会持续消耗摆动的动能
• 物理体默认会进入睡眠状态，系统判定为"静止"后会停止模拟运动

只需要做三处修改就能解决问题：

1. 给摆球的物理体设置linearDamping = 0，消除线性运动的阻尼消耗
2. 禁用场景物理世界的allowsSleeping，避免摆球因静止判定进入睡眠
3. 明确设置关节的shouldEnableLimits = false（默认值为false，显式设置更保险）

修改后的完整代码：

// In viewDidLoad

scene = SKScene(size: view.bounds.size)
scene.backgroundColor = .white
// 禁用物理世界睡眠机制
scene.physicsWorld.allowsSleeping = false

let anchor = SKShapeNode(circleOfRadius: 10)
anchor.physicsBody = .init(circleOfRadius: 10)
anchor.position = .init(x: scene.size.width / 2, y: scene.size.height / 2)
anchor.physicsBody!.isDynamic = false
anchor.physicsBody!.angularDamping = 0
scene.addChild(anchor)

let length: CGFloat = 100

let ball = SKShapeNode(circleOfRadius: 5)
ball.physicsBody = .init(circleOfRadius: 5)
ball.physicsBody!.angularDamping = 0
// 添加线性阻尼设置，消除动能消耗
ball.physicsBody!.linearDamping = 0
ball.position = .init(x: length, y: 0)
anchor.addChild(ball)

let jointPath = CGMutablePath()
jointPath.move(to: .zero)
jointPath.addLine(to: .init(x: length, y: 0))

let joint = SKShapeNode(path: jointPath)
joint.strokeColor = .black
joint.lineWidth = 5
joint.position = anchor.convert(.zero, to: ball)
ball.addChild(joint)

let pin = SKPhysicsJointPin.joint(
    withBodyA: anchor.physicsBody!,
    bodyB: ball.physicsBody!,
    anchor: scene.convert(.zero, from: anchor)
)
pin.frictionTorque = 0
// 明确禁用关节角度限制
pin.shouldEnableLimits = false
scene.physicsWorld.add(pin)

let skView = SKView(frame: view.bounds)
skView.presentScene(scene)
view.addSubview(skView)

修改完成后，单摆就能持续保持摆动状态，不会再逐渐减速停止。

内容的提问来源于stack exchange，提问作者Dyldo42