ios - Sprite 不受物理影响

Question

我想要一个 SKSpriteNode 继续在屏幕上移动并永远随着边缘弹跳。所以我设置了边缘的物理特性:

    let borderBody = SKPhysicsBody(edgeLoopFromRect: self.frame)
    borderBody.friction = 0
    self.physicsBody = borderBody
    physicsWorld.gravity = CGVectorMake(0, 0)

然后是 Sprite 的物理特性:

    ball.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame))
    ball.size = CGSizeMake(30, 30)
    ball.physicsBody = SKPhysicsBody(circleOfRadius: ball.size.width/2)
    ball.physicsBody?.allowsRotation = false
    ball.physicsBody?.restitution = 1.0
    ball.physicsBody?.linearDamping = 0.0
    ball.physicsBody?.friction = 0.0
    ball.physicsBody?.applyImpulse(CGVectorMake(10, -10))

    self.addChild(ball)

问题是 Sprite 无论如何都不会受到物理的影响，而是停留在屏幕的中央。我做错了什么？

Answer 1

您需要先将球添加到您的场景中，然后再将冲量应用到它。

import SpriteKit

class GameScene: SKScene {
    override func didMoveToView(view: SKView) {

        let borderBody = SKPhysicsBody(edgeLoopFromRect: self.frame)
        borderBody.friction = 0
        self.physicsBody = borderBody
        physicsWorld.gravity = CGVectorMake(0, 0)

        let ball = SKSpriteNode(color: SKColor.redColor(), size: CGSizeMake(30, 30))
        ball.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame))
        ball.physicsBody = SKPhysicsBody(circleOfRadius: ball.size.width/2)
        ball.physicsBody?.allowsRotation = false
        ball.physicsBody?.restitution = 1.0
        ball.physicsBody?.linearDamping = 0.0
        ball.physicsBody?.friction = 0.0

        self.addChild(ball)
        ball.physicsBody?.applyImpulse(CGVectorMake(10, -10))
    }
}