Calculated distance between SKNodes does not change although they are moving - ios

Question

I am trying to find the distance between two nodes, specifically rocks. Now this is simple math; but I am running into a problem. I want to check to see if the topRock is within a distance, that distance is to be determined, of btmRock. The code I have is ->
extension CGPoint {
func distanceFromCGPoint(point:CGPoint)->CGFloat{
return sqrt(pow(self.x - point.x,2) + pow(self.y - point.y,2))
}
}
Now in my update function I have ->
var updateTopTime : Double = 0
var updateBottomTime : Double = 0
var genInterval : Double = 2
var genOffset : Double = 3.5
override func update(_ currentTime: TimeInterval) {
moveBackgroundImg()
//optional prevents generation if game is not playing
//guard gameState == .playing else { return }
if updateTopTime == 0 {
updateTopTime = currentTime
}
if updateBottomTime == 0 {
updateBottomTime = currentTime
}
if currentTime - updateBottomTime > genOffset {
createBtmRock()
genOffset = genInterval
updateBottomTime = currentTime
}
else if currentTime - updateTopTime > genInterval {
createTopRock()
updateTopTime = currentTime
}
var distance = btmRock.position.distanceFromCGPoint(point: topRock.position)
print(distance)
if distance <= 10 {
btmRock.position.x += 10
}
if holdingTouch{
progressBar.progress -= 0.001
voloc += 15
plane.physicsBody?.velocity = CGVector(dx: 0, dy: voloc)
//plane.physicsBody?.applyImpulse(CGVector(dx: 0, dy: ))
}
}
The problem is that distance returns 244.201193259997. My topRock and btmRock are randomly generated as well as they move. Even when the nodes are moving the result stays the same. This is how I move my nodes ->
func moveBackgroundImg(){
self.enumerateChildNodes(withName: "BackgroundImg", using: ({
(node, error) in
node.position.x -= self.backgroundMovingSpeed
if node.position.x < -((self.scene?.size.width)!){
node.position.x += (self.scene?.size.width)! * 3
}
}))
self.enumerateChildNodes(withName: "GroundImg", using: ({
(node, error) in
node.position.x -= self.backgroundMovingSpeed
if node.position.x < -((self.scene?.size.width)!){
node.position.x += (self.scene?.size.width)! * 3
}
}))
self.enumerateChildNodes(withName: "TopRock", using: ({
(node, error) in
node.position.x -= self.backgroundMovingSpeed
if node.position.x < -((self.scene?.size.width)!){
node.removeFromParent()
}
}))
self.enumerateChildNodes(withName: "BtmRock", using: ({
(node, error) in
node.position.x -= self.backgroundMovingSpeed
if node.position.x < -((self.scene?.size.width)!){
node.removeFromParent()
}
}))
}
I am confused on how my nodes are created randomly so they have different x and y points; but I am still getting 244.201193259997. If it helps this is how my nodes are created ->
func setupRocks() {
//create the base bottom rock
var btmRockChoice = [SKTexture(image: #imageLiteral(resourceName: "rock")), SKTexture(image: #imageLiteral(resourceName: "rockGrass")), SKTexture(image: #imageLiteral(resourceName: "rockSnow")), SKTexture(image: #imageLiteral(resourceName: "rockIce"))]
btmRock = SKSpriteNode(texture: btmRockChoice[mapChoice], size: CGSize(width: (self.scene?.size.width)! / 10, height: (self.scene?.size.height)! / 2.2))
btmRock.zPosition = -9
btmRock.position = CGPoint(x: self.frame.width, y: frame.minY + btmRock.frame.height / 2)
btmRock.name = "BtmRock"
btmRock.physicsBody = SKPhysicsBody(texture: btmRockChoice[mapChoice], size: CGSize(width: (self.scene?.size.width)! / 10, height: (self.scene?.size.height)! / 2.2))
btmRock.physicsBody?.categoryBitMask = physicsCatagory.topRock
btmRock.physicsBody?.collisionBitMask = physicsCatagory.plane
btmRock.physicsBody?.contactTestBitMask = physicsCatagory.plane
btmRock.physicsBody?.affectedByGravity = false
btmRock.physicsBody?.isDynamic = false
//create the base top rock
var topRockChoice = [SKTexture(image: #imageLiteral(resourceName: "rockDown")), SKTexture(image: #imageLiteral(resourceName: "rockGrassDown")), SKTexture(image: #imageLiteral(resourceName: "rockSnowDown")), SKTexture(image: #imageLiteral(resourceName: "rockIceDown"))]
topRock = SKSpriteNode(texture: topRockChoice[mapChoice], size: CGSize(width: (self.scene?.size.width)! / 10, height: (self.scene?.size.height)! / 2.2))
topRock.zPosition = -9
topRock.name = "TopRock"
topRock.position = CGPoint(x: self.frame.width + topRock.size.width * 2, y: frame.maxY - topRock.frame.height / 2)
topRock.physicsBody = SKPhysicsBody(texture: topRockChoice[mapChoice], size: CGSize(width: (self.scene?.size.width)! / 10, height: (self.scene?.size.height)! / 2.2))
topRock.physicsBody?.categoryBitMask = physicsCatagory.topRock
topRock.physicsBody?.collisionBitMask = physicsCatagory.plane
topRock.physicsBody?.contactTestBitMask = physicsCatagory.plane
topRock.physicsBody?.affectedByGravity = false
topRock.physicsBody?.isDynamic = false
}
func createTopRock() {
//You can make this number a class variable to increase the rate as the game progresses
let randomNum = arc4random_uniform(2)
//there is a 1 in 3 chance that this rock will get created
if randomNum == 0 {
let rock = topRock.copy() as! SKSpriteNode
self.addChild(rock)
}
}
func createBtmRock() {
//You can make this number a class variable to increase the rate as the game progresses
let randomNum = arc4random_uniform(2)
//there is a 1 in 2 chance that this rock will get created
if randomNum == 0 {
let rock = btmRock.copy() as! SKSpriteNode
self.addChild(rock)
}
}
override func didMove(to view: SKView) {
spawnDelayForeverTop = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(self.createTopRock), userInfo: nil, repeats: false)
spawnDelayForeverBtm = Timer.scheduledTimer(timeInterval: 2, target: self, selector: #selector(self.createBtmRock), userInfo: nil, repeats: false)
}
UPDATE: I believe it has something to do with anchor points but I am unsure.

Answer 1

You topRock and bottomRock nodes are not actually the ones you see in your scene and are not added as children. What you're adding to the scene are copies of these two "template" objects. The position of topRock and bottomRock are never changed because they are not part of the scene's children (and I don't see any place in your code where you change the position of these two instances)