Sprite Kit camera smooth movement with delay

Question

So, I can make camera move with player, but it doesn't act the way I need it. I have set word boundaries:

func keepPlayerInBounds() {
    if player.position.x < frame.minX + player.size.width/2 {
        player.position.x = frame.minX + player.size.width/2
    }

    if player.position.x > frame.maxX + player.size.width/2 {
        player.position.x = frame.maxX + player.size.width/2
    }
}

So I need camera max and min X to be to as max and mix X player position in the worldNode. And move it smooth with delay as player moves right or left. I was trying to set:

override func didFinishUpdate()
    cam.position.x = player.position.x
}

Or:

override func didFinishUpdate() {
    let move = SKAction.moveTo(x: player.position.x, duration: 0.5)
    cam.run(move)
}

But it brings more headache than needed.

The question is: how to set left and right max position to the camera, and move it with delay without bugs. I spend almost three weeks to find the answer, but still got nothing. Thanks!

What do you understand by "smooth movement"? What bugs or headaches do you encounter? — Marc, May 13 '17 at 14:45

score 2 · Accepted Answer · answered Jun 02 '17 at 20:32

An easier way to keep your play in bounds is to set a physics body to the player, and a physics body for the bounds.

var player: SKSpriteNode! //player variable
var map: SKSpriteNode! //this simple node called map is a variable that represents the bounds area, for the example i made it the size of the scene (inside GameScene.sks)

override func didMove(to view: SKView) {
    player = childNode(withName: "player") as! SKSpriteNode // initializing the player from the scene file.
    player.physicsBody = SKPhysicsBody(rectangleOf: player.size) // initializing player physics body(in this example the player is a simple rectangle).

    map = childNode(withName: "map") as! SKSpriteNode // initializing the map from the scene file.
    map.physicsBody = SKPhysicsBody(edgeLoopFrom: map.frame) // instead of assigning a physics body to the scene it self, we created the map variable and assign the physics body to it, the edgeLoopFrom physics body  is a static volume-less body, so the player will not be able to pass through.

    setupCamera() // for the second part of your question we create this method and call it right here in viewDidLoad().
}

instead of updating the camera position constantly in the update() method, you simply need to add the camera constraints. (I added the camera in the scene file as well)

func setupCamera() {
    guard let camera = camera, let view = view else { return } // make sure we have a camera and a view or else return

    let zeroDistance = SKRange(constantValue: 0)
    let playerConstraint = SKConstraint.distance(zeroDistance,
                                                 to: player) // as the name suggest this is a simple constraint for the player node.
    //next part of the method will assign a second constraint to the camera which will prevent the camera from showing the dark area of the scene in case the player will go to the edge. you don't have to add this part but it is recommended.
    let xInset = min(view.bounds.width/2 * camera.xScale,
                     map.frame.width/2)
    let yInset = min(view.bounds.height/2 * camera.yScale,
                     map.frame.height/2)

    let constraintRect = map.frame.insetBy(dx: xInset,
                                                  dy: yInset)

    let xRange = SKRange(lowerLimit: constraintRect.minX,
                         upperLimit: constraintRect.maxX)
    let yRange = SKRange(lowerLimit: constraintRect.minY,
                         upperLimit: constraintRect.maxY)

    let edgeConstraint = SKConstraint.positionX(xRange, y: yRange)
    edgeConstraint.referenceNode = map

    camera.constraints = [playerConstraint, edgeConstraint] //finally we add the constraints we created to the camera, notice that the edge constraint goes last because it has a higher priority.
}

Sprite Kit camera smooth movement with delay

1 Answers1