I am trying to create a mario style rotating platform that stays horizontal.
What I have done so far is create a simple class for this for testing purposes.
class PlatformRound: SKNode {
let platform: Platform
// MARK: - Init
init(barSize: CGSize, color: SKColor, pos: CGPoint) {
/// Base
let base = SKShapeNode(circleOfRadius: 6)
//base.name = Platform.Name.normal
base.fillColor = SKColor.darkGrayColor()
base.strokeColor = base.fillColor
base.position = pos
let rotatingAction = SKAction.rotateByAngle(CGFloat(-M_PI), duration: 8)
base.runAction(SKAction.repeatActionForever(rotatingAction))
/// Bar
let bar = Platform(size: barSize, color: color, pos: CGPointMake(0, 0 - (barSize.height / 2)), ofType: .Normal)
bar.zPosition = -200
/// Platform that supposed to stay horizontal
let platformSize = CGSizeMake(40, GameplayConfig.World.platformHeight)
let platformPos = CGPointMake(0, 0 - (bar.size.height / 2))
platform = Platform(size: platformSize, color: color, pos: platformPos, ofType: .Normal)
super.init()
addChild(base)
base.addChild(bar)
bar.addChild(platform)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
I am creating a roundBase that I can rotate. I than create a bar that goes down from the base, that is added to the base node. Finally I create the platform that is supposed to stay horizontal at all times.
I am using another Platform subclass to create the bar and platform, but they are not relevant to this question.
How can I make the platform stay horizontal. I tried the following which didnt work.
1) In update in my gameScene I constantly update the platform position or zRotation
platformRound.platform.zRotation = ...
2) Create a zRotation property that gets set once the platform is added and than use that property to constantly update the zRotation.
3) Tried playing around with physicsJoints
Im sure there is a easy way that I am missing. I would appreciate any help.
This should work:
class GameScene: SKScene{
override func didMoveToView(view: SKView) {
backgroundColor = .blackColor()
let centerSprite = SKSpriteNode(color: .whiteColor(), size: CGSize(width: 10, height: 10))
centerSprite.zPosition = 3
let platform = SKSpriteNode(color: .orangeColor(), size: CGSize(width: 70, height: 20))
platform.zPosition = 2
platform.name = "platform"
let container = SKNode()
container.position = CGPoint(x: frame.midX, y: frame.midY)
container.addChild(centerSprite) //Just for debugging
container.addChild(platform)
let radius = 120
let chain = SKSpriteNode(color: .grayColor(), size: CGSize(width: 3, height: radius))
chain.position = CGPoint(x: 0, y: radius/2)
container.addChild(chain)
platform.position = CGPoint(x: 0, y: radius)
let rotatingAction = SKAction.rotateByAngle(CGFloat(-M_PI), duration: 8)
container.runAction(SKAction.repeatActionForever(rotatingAction), withKey: "rotating")
addChild(container)
}
override func didEvaluateActions() {
self.enumerateChildNodesWithName("//platform") { node,stop in
if let parent = node.parent{
node.zRotation = -parent.zRotation
}
}
}
}
What I did, is that I have added platform node into container node and applied rotation to that container. Later on, in didEvaluateActions I've adjusted the rotation of platform (to have a negative value of its parent's zRotation). And that's it.
Here is the result of what I am seeing:
The adjusting is needed, because otherwise the platform will end-up rotating along with its parent (notice how white, center sprite is being rotated along with container node).
Related
I tried to create some kind of timeline (with the Vector Illustrator mentality), using UIBezier and UI Label (kind of like in the calendar app) and then use UIPanGestureRecognizer to scroll it up and down. But whenever I scroll it in the simulator, it multiplies itself instead of moving like the images below (I use setNeedsDisplay as the scrollValue changes to redraw the whole mechanism). This is probably a small mistake a I did or maybe my code doesn't work.
I know I could use a UIScrollView or UITableView instead, but I tried making this as a small challenge as a custom made table because using pre-made objects feels limiting for someone like me who is used to CAD drawing or Vector Illustrator.
This image explains what happens in the Simulator:
The code I used is below:
import UIKit
class ViewController: UIViewController {
var tlobject = TimelineView()
let gesto = UIPanGestureRecognizer()
override func viewDidLoad() {
super.viewDidLoad()
// ===== Add TimelineView Object to view
let TLObjectFrame = CGRect(x: 0, y: 40, width: 100, height: 100)
tlobject = TimelineView(frame: TLObjectFrame)
view.addSubview(tlobject)
// ===== ADD TOUCH GESTURE =====
gesto.addTarget(self, action: #selector(touchinput))
view.addGestureRecognizer(gesto)
}
var touchStartLocation: Int = 0
var scrollDistance: Int = 0
var lastScrollDistance: Int = 0
//The following func calculates the distance scrolled/travelled by Touch gesture on the YAxis and sends the result value (scrollDistance) to the Timeline mechanism where it defines the Yposition of every UIBezier. Thanks to Mitchell Hudson on Youtube for helping me figure out how to do it on his Tutorial "06 11 touches value"
#objc func touchinput (sender: UIPanGestureRecognizer) {
if sender.state == UIGestureRecognizer.State.began {
touchStartLocation = Int(sender.location(in: view).y)
lastScrollDistance = scrollDistance
}
if sender.state == UIGestureRecognizer.State.changed {
let touchEndLocation = Int(sender.location(in: view).y)
let currentScrollDistance = touchEndLocation - touchStartLocation
print("deltaY", currentScrollDistance)
var newScrollDistance = lastScrollDistance + currentScrollDistance
scrollDistance = newScrollDistance
tlobject.totalScrollDistance = scrollDistance //send scrollValue to TimelineView
}
if sender.state == UIGestureRecognizer.State.ended {
print("lastScrollDistance", lastScrollDistance)
print("scroll Distance", scrollDistance)
}
}
}
//Created a new View with the TimeLine mechanism
class TimelineView: UIView {
var totalScrollDistance: Int = 0 {
didSet{
setNeedsDisplay() //this gets called everytime UIgesture position changes
}
}
override init(frame: CGRect) {
super.init(frame: frame)
self.backgroundColor = UIColor.clear
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
override func draw(_ rect: CGRect) {
timelinemechanism()
}
func timelinemechanism() {
let lineElements: Array = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
let spacing: Int = 30
let scrollDistance: Int = totalScrollDistance
let totalElements: Int = lineElements.count
for n in 1...totalElements {
//Get UILabel/UILine Yposition on screen = Array index number * the spacing + scroll distance by touch pan gesture
let yPosition = lineElements[n - 1] * spacing + scrollDistance
let linepath = UIBezierPath()
linepath.move(to: CGPoint(x: 60, y: yPosition))
linepath.addLine(to: CGPoint(x: 300, y: yPosition))
let lineshape = CAShapeLayer()
lineshape.path = linepath.cgPath
lineshape.strokeColor = UIColor.blue.cgColor
//lineshape.fillColor = UIColor.white.cgColor
//lineshape.lineWidth = 1
self.layer.addSublayer(lineshape)
let hourlabel = UILabel()
hourlabel.frame = CGRect(x: 5, y: yPosition - 20, width: 45, height: 40)
hourlabel.text = "\(n):00"
//hourlabel.font = UIFont(name: "Avenir-Claro", size: 12)
hourlabel.textColor = UIColor.blue
hourlabel.textAlignment = NSTextAlignment.right
self.addSubview(hourlabel)
}
}
}
Inside draw you only have to draw something. You add new subviews/sublayers and do not remove old ones.
Creating a new view every time you change a frame is very resource-intensive. And you don't need that, because you have the same views, you only need to change the position.
Instead, you can create your views at start and use layoutSubviews to update your views positions:
class TimelineView: UIView {
var totalScrollDistance: Int = 0 {
didSet{
setNeedsLayout() //this gets called everytime UIgesture position changes
}
}
private var lastLayoutTotalScrollDistance: Int = 0
override init(frame: CGRect) {
super.init(frame: frame)
self.backgroundColor = UIColor.clear
createTimelinemechanism()
}
required init?(coder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
var lineShapes = [CAShapeLayer]()
var hourLabels = [UILabel]()
override func layoutSubviews() {
super.layoutSubviews()
let offset = totalScrollDistance - lastLayoutTotalScrollDistance
lastLayoutTotalScrollDistance = totalScrollDistance
lineShapes.forEach { lineShape in
lineShape.frame.origin.y += CGFloat(offset)
}
hourLabels.forEach { hourLabel in
hourLabel.frame.origin.y += CGFloat(offset)
}
}
func createTimelinemechanism() {
let lineElements: Array = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
let spacing: Int = 30
let totalElements: Int = lineElements.count
for n in 1...totalElements {
//Get UILabel/UILine Yposition on screen = Array index number * the spacing + scroll distance by touch pan gesture
let yPosition = lineElements[n - 1] * spacing
let linepath = UIBezierPath()
linepath.move(to: CGPoint(x: 60, y: yPosition))
linepath.addLine(to: CGPoint(x: 300, y: yPosition))
let lineshape = CAShapeLayer()
lineshape.path = linepath.cgPath
lineshape.strokeColor = UIColor.blue.cgColor
//lineshape.fillColor = UIColor.white.cgColor
//lineshape.lineWidth = 1
// disable default layer position animation
lineshape.actions = [
"position": NSNull(),
]
self.layer.addSublayer(lineshape)
lineShapes.append(lineshape)
let hourlabel = UILabel()
hourlabel.frame = CGRect(x: 5, y: yPosition - 20, width: 45, height: 40)
hourlabel.text = "\(n):00"
//hourlabel.font = UIFont(name: "Avenir-Claro", size: 12)
hourlabel.textColor = UIColor.blue
hourlabel.textAlignment = NSTextAlignment.right
self.addSubview(hourlabel)
hourLabels.append(hourlabel)
}
}
}
More generally, you can just list all the subviews/sublayers and not keep them in separate containers.
I spent a bit more time with your question since my first thought was wrong. Let me start by saying that your approach here is not the right way to go about this. But it looks to me like you're playing with different aspects of the framework just to learn your way around and I can respect that. I spent many years working on as vector drawing program (Macromedia FreeHand) and even wrote a book about drawing with Quartz 2D back in 2006 so I understand the desire to draw it yourself.
I've reworked your example using "raw" drawing at the CGContext level. I was playing with your code in a Playground so I restructured the view creation a bit too (just so it shows up in the Playground nicely). You should be able to copy and paste this into an iOS playground and see the results.
//: A UIKit based Playground for presenting user interface
import UIKit
import PlaygroundSupport
class ViewController: UIViewController {
let gesto = UIPanGestureRecognizer()
let timelineView = TimelineView()
override func viewDidLoad() {
super.viewDidLoad()
view.translatesAutoresizingMaskIntoConstraints = true
self.view.backgroundColor = UIColor.red
self.view.bounds = CGRect(x:0, y:0, width: 320, height: 700)
// ===== Add TimelineView Object to view
view.addSubview(timelineView)
timelineView.frame = CGRect(x: 20, y: 20, width: 280, height: 660)
timelineView.backgroundColor = UIColor.white
debugPrint(timelineView.bounds)
// ===== ADD TOUCH GESTURE =====
gesto.addTarget(self, action: #selector(touchinput))
timelineView.addGestureRecognizer(gesto)
}
var touchStartLocation: Int = 0
var scrollDistance: Int = 0
var lastScrollDistance: Int = 0
//The following func calculates the distance scrolled/travelled by Touch gesture on the YAxis and sends the result value (scrollDistance) to the Timeline mechanism where it defines the Yposition of every UIBezier. Thanks to Mitchell Hudson on Youtube for helping me figure out how to do it on his Tutorial "06 11 touches value"
#objc func touchinput (sender: UIPanGestureRecognizer) {
if sender.state == UIGestureRecognizer.State.began {
touchStartLocation = Int(sender.location(in: view).y)
lastScrollDistance = scrollDistance
}
if sender.state == UIGestureRecognizer.State.changed {
let touchEndLocation = Int(sender.location(in: view).y)
let currentScrollDistance = touchEndLocation - touchStartLocation
print("deltaY", currentScrollDistance)
scrollDistance = lastScrollDistance + currentScrollDistance
timelineView.totalScrollDistance = scrollDistance //send scrollValue to TimelineView
}
if sender.state == UIGestureRecognizer.State.ended {
print("lastScrollDistance", lastScrollDistance)
print("scroll Distance", scrollDistance)
}
}
}
//Created a new View with the TimeLine mechanism
class TimelineView: UIView {
var totalScrollDistance: Int = 0 {
didSet {
setNeedsDisplay() //this gets called everytime UIgesture position changes
}
}
override func draw(_ rect: CGRect) {
if let cgContext = UIGraphicsGetCurrentContext() {
drawTimeline(cgContext: cgContext)
}
}
func drawTimeline(cgContext: CGContext) {
let numElements = 10
let spacing = 30
let scrollDistance = totalScrollDistance
for n in 0..<numElements {
let yPosition = n * spacing + scrollDistance
cgContext.saveGState()
cgContext.setLineWidth(1.0)
cgContext.setStrokeColor(UIColor.blue.cgColor)
cgContext.move(to: CGPoint(x: 60, y: yPosition))
cgContext.addLine(to: CGPoint(x: 300, y: yPosition))
cgContext.strokePath()
let label : NSString = "\(n):00" as NSString
label.draw(at: CGPoint(x: 5, y: yPosition - 20),
withAttributes: [.foregroundColor : UIColor.blue])
cgContext.restoreGState()
}
}
}
// Present the view controller in the Live View window
PlaygroundPage.current.liveView = ViewController()
The drawRect of the custom view grabs the current CGContext and passes it to the routine that does the drawing. Using something like UIBezierPath will work, of course (you saw that it did) but it has overhead (creating an actual object, copying the object into the context graphics state on each drawing, etc) that you don't necessarily need.
I'm not sure what you were doing with CAShapeLayer. You'd typically use that if you had a shape that you want to animate around the screen. I suppose you felt that, in scrolling, you might want to do that. But again this is something where you'd want to create the shape layer outside of the drawing path, keep ahold of it, manipulate it outside of the drawing path, then let the system handle worry about putting it on the screen appriopriately.
Your instincts on text are pretty good. You really don't want to handle Text drawing yourself in a system as complex as iOS. There's Unicode issues, glyph substitution, positional forms, ligatures, bi-di text... a whole host of challenges for drawing text on iOS that it's best to leave to things like UILabel. But you want to keep building your view hierarchy separate from drawing in your view hierarchy. drawRect can be called any time even a pixel of your view needs to be redrawn and adding a new subview each time is not the best way to go. In my reworked example, I'm drawing the text using NSString - It's still not the "right" way to do it but it's fairly low level while still giving the framework a chance to do some of the text handling.
In the end you would want to work with the frameworks instead of against them. You'd want to use something like UIScrollView because it will handle a thousand details (bouncing at the boundaries, ease-in/ease-out animation, touch point tracking, fast and slow scrolling, etc) but for a learning experience your code is just fine and I hope you enjoy working with iOS more!
Working on a game right now, I've faced a problem regarding management of SkSpriteNodes. I have a SpriteNode whose texture size is lower than physicsBody size assigned to it. It is possible to move, thanks to something similar to an SKAction, only the texture of a node and not its physicsBody?
To explain the problem in other terms, I will give you a graphic example:
As you can see, what I want to achieve is not to modify physicsBody proprieties(in order to not affect collision or having problems with continuos reassigning of PhysicsBody entities), but changing its texture length and adjusting its position. How can I achieve this programmatically?
A bit of code for context, which is just illustrative of the problem:
let node = SKSpriteNode(color: .red, size: CGSize(width: 8, height: 60)
node.physicsBody = SKPhysicsBody(rectangleOf: CGSize(width: 8, height: 60)
self.addChild(node)
//what I've tried is something like that
//It causes glitches in visualisation... and I need to move the object since resizing is towards the center.
let resize = SKAction.scaleY(to: 0.5, duration: 5)
let move = SKAction.move(to: node.position - CGPoint(x:0, y:node.size.height*0.5), duration: 5)
let group = SKAction.group([resize, move])
node.run(group)
//And this is even worse if I add, in this specific example, another point fixed to the previous node
let node2 = SKSpriteNode(color: .blue, size: CGSize(width: 8, length: 8)
node2.physicsBody = SKPhysicsBody(rectangleOf: CGSize(width: 8, height: 8))
node2.position = CGPoint(x: 0, y: -node.height)
self.addChild(node2)
self.physicsWorld.add(SKPhysicsJointFixed.joint(withBodyA: node.physicsBody! , bodyB: node2.physicsBody!, anchor: CGPoint(x: 0, y: -node.size.height)))
I get your problem.
let resize = SKAction.scaleY(to: 0.5, duration: 5)
This line will cause the physicsBody to scale the x and y axis uniformly. While your texture will just scale the y axis.
Its not so straight forward changing physicsBody shapes to match actions
One way to do it though would be to call a method from
override func didEvaluateActions()
Something like this:
var group1: SKAction? = nil
var group2: SKAction? = nil
var touchCnt = 0
var test = SKSpriteNode(texture: SKTexture(imageNamed: "circle"), color: .blue, size: CGSize(width: 100, height: 100))
func setActions() {
let newPosition = CGPoint(x: -200, y: 300)
let resize1 = SKAction.scaleY(to: 0.5, duration: 5)
let move1 = SKAction.move(to: newPosition, duration: 5)
group1 = SKAction.group([resize1, move1])
let resize2 = SKAction.scaleY(to: 1, duration: 5)
let move2 = SKAction.move(to: position, duration: 5)
group2 = SKAction.group([resize2, move2])
}
func newPhysics(node: SKSpriteNode) {
node.physicsBody = SKPhysicsBody(texture: node.texture!, size: node.size)
node.physicsBody?.affectedByGravity = false
node.physicsBody?.allowsRotation = false
node.physicsBody?.usesPreciseCollisionDetection = false
}
override func sceneDidLoad() {
physicsWorld.contactDelegate = self
test.position = CGPoint(x: 0, y: 300)
setActions()
newPhysics(node: test)
addChild(test)
}
override func didEvaluateActions() {
newPhysics(node: test)
}
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
if touchCnt == 0 {
if !test.hasActions() {
test.run(group1!)
touchCnt += 1
}
} else {
if !test.hasActions() {
test.run(group2!)
touchCnt -= 1
}
}
}
if you put the above code in your gameScene, taking care to replace any duplicated methods and replacing the test node texture. then when you tap the screen the sprite should animate as you want while keeping the physics body is resized at the same time. There are a few performance issues with this though. As it changes the physics body on each game loop iteration.
I'm new in Sprite Kit and I have a strange problem with my GameScene. Can't figure out, what causes the problem. I present my scene from controller in viewWillAppearMethod in this way:
let atlas = SKTextureAtlas(named: "Sprites")
atlas.preload { [unowned self] in
DispatchQueue.main.async {
self.gameScene = GameScene(level: self.level, size: self.gameSKView!.bounds.size)
self.gameScene.scaleMode = .resizeFill
self.gameSKView?.presentScene(self.gameScene)
self.gameSKView?.ignoresSiblingOrder = true
self.gameSKView?.showsNodeCount = true
}
}
My sprite atlas content looks like: link
Than i create my spaceship:
final class SpaceshipSpriteNode: SKSpriteNode {
required init(size: CGSize) {
let texture = SKTexture(image: #imageLiteral(resourceName: "Spaceship"))
super.init(texture: texture, color: .white, size: size)
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
}
func configureSpaceship() {
let middleRow = Int(Double(unwrappedMatrix.rowsCount) / 2)
let middleColumn = Int(Double(unwrappedMatrix.columnsCount) / 2)
let xOffset = CGFloat(level.startPoint.column - middleColumn)
let yOffset = CGFloat(level.startPoint.row - middleRow)
spaceship = SpaceshipSpriteNode(size: spaceshipSize)
spaceship.position = CGPoint(x: frame.midX + (spaceshipSize.width * xOffset), y: frame.midY + (spaceshipSize.height * yOffset))
spaceshipObject.addChild(spaceship)
addChild(spaceshipObject)
}
configureSpaceship method is called in didMove(to view: SKView)
The problem is that sometimes(1 per 3/4/5/6 cases) my spaceship is missing from the scene. Visibility, position, size are always the same, a count of the nodes on scene is the same too. Some images here link
According to comments, I have changed zPosition for my objects:
tile.zPosition = 0
spaceship.zPosition = 1.0
backgroundSpriteNode.zPosition = -1
And everything start working correct, thanks guys.
Any ideas as to why my Sprites aren't appearing in the correct order here? The snowflake shows up at index 0 instead of 1.
Even if I switch the order around, the snowflake still appears behind everything else.
import Foundation
import SpriteKit
class page1: SKScene {
let background = SKSpriteNode(imageNamed: "01_BG")
let snowflake = SKSpriteNode(imageNamed: "home_snowflake02")
let room = SKSpriteNode(imageNamed: "01_room")
let kid = SKSpriteNode(imageNamed: "01_kidStanding")
override init(size: CGSize){
super.init(size: size)
}
override func didMoveToView(view: SKView) {
//Set up background
background.position = CGPoint(x: 200, y: 380)
background.xScale = 1.0
background.yScale = 1.0
insertChild(background, atIndex: 0)
//Set up Snowflakes
snowflake.position = CGPoint(x: 250, y: 1100)
snowflake.xScale = 1.0
snowflake.yScale = 1.0
insertChild(snowflake, atIndex: 1)
//Set up room
room.position = CGPoint(x: 512, y: 384)
room.xScale = 1.0
room.yScale = 1.0
insertChild(room, atIndex: 2)
//Set up kid
kid.position = CGPoint(x: 320, y: 290)
kid.xScale = 1.0
kid.yScale = 1.0
insertChild(kid, atIndex: 3)
}
required init?(coder aDecoder: NSCoder) {
fatalError("init(coder:) has not been implemented")
}
}
If your scenes view has it's ignoresSiblingOrder property set to true, performance can be improved but the order of sibling sprites is unreliable.
You can set a sprites zPosition directly to deal with this.
eg:
background.zPosition = 0
snowflake.zPosition = 1
or
snowflake.zPosition = background.zPosition + 1
to keep it relative to a sibling.
Ok. this code is driving me crazy. It just don't work. The only message I received is "Attemped to add a SKNode which already has a parent". Yes I know that there has been some discussions here, but none of them give the solution I need.
This is the code. I really appreciate any help.
import SpriteKit
class MyScene: SKScene {
let intervalShapeCreation:NSTimeInterval = 2.0 // Interval for creating the next Shape
let gravitationalAcceleration:CGFloat = -0.5 // The gravitational Y acceleration
let shapeSequenceAction = SKAction.sequence([
SKAction.scaleTo(1.0, duration: 0.5),
SKAction.waitForDuration(2.0),
SKAction.scaleTo(0, duration: 0.5),
SKAction.removeFromParent()
])
override init(size: CGSize) {
super.init(size: size)
}
required init(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
}
override func didMoveToView(view: SKView) {
super.didMoveToView(view)
addBackground()
initializeScene()
}
// MARK: Level Building
func initializeScene() {
self.physicsWorld.gravity = CGVectorMake(0.0, gravitationalAcceleration)
runAction(SKAction.repeatActionForever(
SKAction.sequence([SKAction.runBlock(self.createShape),
SKAction.waitForDuration(intervalShapeCreation)])))
}
func addBackground() {
let backgroundAtlas = SKTextureAtlas(named: "background")
let background = SKSpriteNode(texture: backgroundAtlas.textureNamed("background"))
background.position = CGPoint(x: size.width/2, y: size.height/2)
background.anchorPoint = CGPointMake(0.5, 0.5)
background.zPosition = -1
background.name = "background"
self.addChild(background)
}
func createShape() {
let newShape = sSharedAllPossibleShapes[0]
print("\n shape creada: \(newShape.name)")
newShape.position = CGPointMake(size.width / 2, CGFloat( Int.random(fromZeroToMax: 500)))
self.addChild(newShape)
newShape.runAction(shapeSequenceAction)
}
}
createShape doesn't actually create a SKShapeNode. It gets the first shape from the sSharedAllPossibleShapes array, then adds it as child to self. The second time you call this method that shape already has a parent and can't be added again.
You have to create a new instance of SKShapeNode. The way I see it your array here really needs to contain the CGPath objects that define the shape, not the nodes themselves because you can't reuse nodes the way you intended to.