雪碧套件-旋转以面对地面

Question

我做了一个精灵，站在地面上，但是我想让精灵旋转以面对地面，这样看起来好像他在地面上爬行。

func setUpRunner() {
    let runnerSize = CGSizeMake(15, 40)
    Runner = SKShapeNode(rectOfSize: runnerSize)
    Runner.fillColor = SKColor.blackColor()
    Runner.name = self.rName

    Runner.physicsBody = SKPhysicsBody(rectangleOfSize: runnerSize)
    Runner.physicsBody.dynamic = true
    Runner.physicsBody.affectedByGravity = true
    Runner.physicsBody.allowsRotation = false
    Runner.physicsBody.restitution = 0.0
    Runner.physicsBody.categoryBitMask = rCategory
    Runner.physicsBody.contactTestBitMask = groundCategory

    Runner.position = CGPointMake(20, self.frame.height/3)
    self.addChild(Runner)
}

func crouch() {
    Runner.zRotation = 90 //or -90
}

但这会让他面对东北，西北。

Answer 1

看看SKNode的API。 它说

zRotation
The Euler rotation about the z axis (in radians).

这意味着360度是2*M_PI ，因此90度是M_PI/2