how do i make a node go from one side of the screen to the other? - swift

Question

I'm just starting in sprite kit and have hit a road block. I'm trying to recreate the old atari game asteroids. I'm currently trying to find out how to move the node "ship" from one side of the screen and come out the opposite side. An example of this would be pacman going from the right side of the screen and out the left side of the screen. Help is greatly appreciated.
Thanks in advance,
Jared
import SpriteKit
class GameScene: SKScene, SKPhysicsContactDelegate{
let base = SKSpriteNode(imageNamed: "Base")
let ball = SKSpriteNode(imageNamed: "Ball")
let ship = SKSpriteNode(imageNamed: "Ship")
let shoot = SKSpriteNode(imageNamed: "shootButton")
override func didMoveToView(view: SKView){
// var DynamicView=UIView(frame: CGRectMake(100, 200, 100, 100))
// DynamicView.backgroundColor=UIColor.greenColor()
// DynamicView.layer.cornerRadius=2
// DynamicView.layer.borderWidth=2
// self.view!.addSubview(DynamicView)
self.anchorPoint = CGPointMake(0.5, 0.5)
self.physicsWorld.contactDelegate = self
self.physicsWorld.gravity = CGVectorMake(0.0, 0.0)
self.addChild(base)
base.position = CGPointMake(-350, -200)
self.addChild(shoot)
shoot.position = CGPointMake(350, -200)
self.addChild(ball)
ball.position = base.position
self.addChild(ship)
ship.position = CGPointMake(20, 47)
ship.xScale = 0.7
ship.yScale = 0.7
ship.physicsBody?.dynamic = true
ship.physicsBody?.allowsRotation = true
ship.physicsBody?.affectedByGravity = true
ship.physicsBody = SKPhysicsBody(texture: SKTexture(imageNamed: "Ship"), size: ship.size)
self.physicsBody = SKPhysicsBody(edgeLoopFromRect: self.frame)
ball.alpha = 0.4
base.alpha = 0.4
}
// func touchesBegan(touches: Set<NSObject>, withEvent event: UIEvent) {
// /* Called when a touch begins */
//
// for touch in (touches as! Set<UITouch>) {
// let location = touch.locationInNode(self)
//
//
// }
// }
override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {
for touch in (touches ) {
let location = touch.locationInNode(self)
let v = CGVector(dx: location.x - base.position.x, dy: location.y - base.position.y)
let angle = atan2(v.dy, v.dx)
let deg = angle * CGFloat(180 / M_PI)
// print( deg + 180)
let length:CGFloat = base.frame.size.height / 2
let xDist:CGFloat = sin(angle - 1.57079633) * length
let yDist:CGFloat = cos(angle - 1.57079633) * length
ball.position = CGPointMake(base.position.x - xDist, base.position.y + yDist)
if CGRectContainsPoint(base.frame, location) {
ball.position = location
}
else{
ball.position = CGPointMake(base.position.x - xDist, base.position.y + yDist)
}
ship.zRotation = angle - 1.57079633
ship.physicsBody?.mass = 2
var shipRotation : CGFloat = ship.zRotation
var calcRotation : Float = Float(angle - 1.57079633) + Float(M_PI_2);
let intensity : CGFloat = 2000.0 // put your value
let xVelocity = intensity * CGFloat(cosf(calcRotation))
let yVelocity = intensity * CGFloat(sinf(calcRotation))
let vector : CGVector = CGVectorMake(xVelocity, yVelocity)
//Apply force to spaceship
ship.physicsBody?.applyForce(vector)
}
}
override func touchesEnded(touches: Set<UITouch>, withEvent event: UIEvent?) {
let move:SKAction = SKAction.moveTo(base.position, duration: 0.2)
move.timingMode = .EaseOut
ball.runAction(move)
}
}
// overridefunc update(currentTime: CFTimeInterval) {
// /* Called before each frame is rendered */
//
//}

Answer 1

In func update(currentTime) check if ship.position.x < 0 or ship.position.x > scene.width. If true, set ship.position.x to the opposite side.

Answer 2

It looks like you're using physics to move the ship (as opposed to updating its position by a certain amount in the update() method)
So what you could do is to override the didiSimulatePhysics() method (which is called after the SpriteKit game engine has done all the physics calculations and moved all the nodes) and if your ship is off screen (which you could do by seeing if it's position is outside the screne's x & y boundaries, or by using the intersectsRect method to see if. The ship's frame no longer overlaps the screen frame) and if it is, simply wrap it to the other side of the screen.