Working with Cameras in SpriteKit Game

🎤 General Discussion Sprite Kit
1

I’m currently working on a game that has a vertical tileMap and a character toward the bottom of the screen that can only be moved on the x-axis. I started making this game after working through the tutorial for DropCharge in the 2DiOS Games book. Currently to make it look like the game is scrolling I gave my character a velocity of dx:500 to have him travel up the tileMap.

When I run the simulator the camera starts towards the bottom left of everything and then looks like it is catching up to my scene contents. I believe this has to do with the code i implemented for my camera following my player.

override func didSimulatePhysics() {
    cameraNode.position = CGPoint(x: player.parent!.position.x, y: player.parent!.position.y)
    self.centerOnNode(node: cameraNode)
}

func centerOnNode(node: SKNode) {
    let cameraPositionInScene: CGPoint = node.scene!.convert(node.position, from: worldNode)
    node.parent!.run(SKAction.move(to: CGPoint(x:node.parent!.position.x - cameraPositionInScene.x, y:node.parent!.position.y - cameraPositionInScene.y), duration: 2.0))
    
}

How can I have a camera follow a node all the way until the edge of the scene and stop once it reaches the end? I can’t figure out how to give the camera boundaries to stop at on the x axis.

Also, I want my player to be on the same y coordinate the entire game and just have him move horizontally(about 70% down on the screen). How do I implement my velocity to move him up the map, and still keep him on a constant y-axis value?

Here is all of my code:

class GameScene: SKScene, SKPhysicsContactDelegate {
var worldNode = SKNode()
var bgNode = SKNode()
var fgNode = SKNode()
var cameraNode: SKNode!
var background: SKNode!
var player: Character1Node!
var platform: SKTileMapNode!
var previousTranslateX: CGFloat = 0.0




override func didMove(to view: SKView) {
    setupNodes()
    self.anchorPoint = CGPoint(x: 0.5, y: 0.5)
    cameraNode.position = CGPoint(x: size.width/2, y: size.height/2)
    
    //Panning for dragging player
    let pan = UIPanGestureRecognizer(target: self, action: #selector(GameScene.dragPlayer(sender:)))
    self.view?.addGestureRecognizer(pan)
    
    print(worldNode.frame.size)
    print(cameraNode.frame.size)
    print(scene?.frame.size)
    print(view.frame.size)
}

func dragPlayer(sender: UIPanGestureRecognizer) {
    
    //retrieve pan movement along the x-axis of the view since the gesture began
    let currentTranslateX = sender.translation(in: view!).x
    
    //calculate translation since last measurement
    let translateX = currentTranslateX - previousTranslateX
    
    //move shape
    let adjustment:CGFloat = 2.0
    player.parent!.position = CGPoint(x: player.parent!.position.x + (translateX*adjustment), y:player.parent!.position.y)

    
    //reset previous measuremnt
    if sender.state == .ended{
        previousTranslateX = 0
    } else {
        previousTranslateX = currentTranslateX
    }
}



func setupNodes(){
    
    //Connecting variables to scene
    worldNode = childNode(withName: "World")!
    bgNode = worldNode.childNode(withName: "Background")!
    background = bgNode.childNode(withName: "Overlay")!.copy() as! SKNode
    fgNode = worldNode.childNode(withName: "Foreground")!
    cameraNode = worldNode.childNode(withName: "Camera")
    
    //Platform physics
    platform = fgNode.childNode(withName: "Level1Map") as! SKTileMapNode
    let bodySize = CGSize(width: 150, height: 190)
    platform.physicsBody = SKPhysicsBody(rectangleOf: bodySize)
    platform.physicsBody!.isDynamic = true
    platform.physicsBody!.affectedByGravity = false
    platform.physicsBody!.linearDamping = 0
    platform.physicsBody!.categoryBitMask = PhysicsCategory.Platform
    platform.physicsBody!.collisionBitMask = PhysicsCategory.None
    platform.physicsBody!.velocity = CGVector(dx: 0, dy: 0)
    
    enumerateChildNodes(withName: "//*", using: {node, _ in
        if let customNode = node as? CustomNodeEvents {
            customNode.didMoveToScene()
        }
    })
    
    player = platform.childNode(withName: "//character1") as! Character1Node
    
    
}

override func update(_ currentTime: TimeInterval) {
    let position = player.parent!.position
    
    //Platform Tiles
    let column = platform.tileColumnIndex(fromPosition: position)
    let row = platform.tileRowIndex(fromPosition: position)
    let objectTile = platform.tileDefinition(atColumn: column, row: row)
    //print(objectTile)
    
    if let _ = objectTile?.userData?.value(forKey: "tile2"){
        print("jumping tile")
    }
    
    if let _ = objectTile?.userData?.value(forKey: "tile1"){
        print("platform tile")
    }
    
    print(player.parent!.position)


}

override func didSimulatePhysics() {
    cameraNode.position = CGPoint(x: player.parent!.position.x, y: player.parent!.position.y)
    self.centerOnNode(node: cameraNode)
}

func centerOnNode(node: SKNode) {
    let cameraPositionInScene: CGPoint = node.scene!.convert(node.position, from: worldNode)
    node.parent!.run(SKAction.move(to: CGPoint(x:node.parent!.position.x - cameraPositionInScene.x, y:node.parent!.position.y - cameraPositionInScene.y), duration: 2.0))
    
}
2

I can’t test any code to put up a functional reply but check against the edges of the camera with something like this

public func checkCamera(camera: SKCamera) {
if camera.position - camera.size.width < 0 {
return true
} else if camera.position + camera.size.width > scene.size.width {
return true
} else { return false }
}

then if it returns true don’t move the camera

3

To achieve a camera that follows the player horizontally until the edge of the scene and keeps the player GMSocrates at a constant y-coordinate, calculate camera boundaries, constrain camera movement, adjust player velocity, and set player’s y-position. Remember to replace placeholder values with your desired values.