So I'm creating a game in Swift with Spritekit and have ran into an issue with getting my game to work. I'm still a beginner with programming so I've likely missed out on a solution to this myself.
Anyway, so the game concept is a simple arcade vertical scroller that involves a player trying to dodge platforms as it descends downward. The mechanics (so far) are a stationary player on the y axis that can move left and right along the x axis while the platforms scroll upward along with the background moving with the platforms to give a visual effect of descent. I've gotten a build working to be fully playable, but there's an issue with spawning the platforms perfectly spaced out. Here's a sketch:
The picture on the left what I'm trying to achieve, while the one on the right is my current and flawed method. The main issue with the one on the right, is that it uses a collision to trigger spawning which means the spawn trigger node (red line) has to be 1 pixel tall to allow for perfect spacing. If the spawn trigger node is more than 1 pixel tall, then the collision may not trigger on that the first pixel of contact and trigger the node a few pixels deep which throws off the entire spacing. Also if the spawn trigger is only 1 pixel tall, it often won't trigger unless the everything is scrolling at slow speeds.
I've tried to think of other methods to approach this but I'm at a loss. I cannot use a simple timer to spawn nodes at intervals because the speed at which the game scrolls is variable and is constantly changing by player controls. The only two other options I can think of (which I don't know how to do either) is either spawn node sets at fixed y-positions and set that on a loop, or change it so the player is actually descending downward while everything is generating around it (seems tougher and maybe unnecessary). I'm considering just rewriting my createPlatforms() method if I need to, but here's the code for that and the background anyway:
var platformGroup = Set<SKSpriteNode>()
var platformSpeed: CGFloat = 0.6 { didSet { for platforms in platformGroup { platforms.speed = platformSpeed } } }
var platformTexture: SKTexture!
var platformPhysics: SKPhysicsBody!
var platformCount = 0
var backgroundPieces: [SKSpriteNode] = [SKSpriteNode(), SKSpriteNode()]
var backgroundSpeed: CGFloat = 1.0 { didSet { for background in backgroundPieces { background.speed = backgroundSpeed } } }
var backgroundTexture: SKTexture! { didSet { for background in backgroundPieces { background.texture = backgroundTexture } } }
func createPlatforms() {
let min = CGFloat(frame.width / 12)
let max = CGFloat(frame.width / 3)
var xPosition = CGFloat.random(in: -min ... max)
if platformCount >= 20 && platformCount < 30 {
stage = 0
setTextures()
xPosition = frame.size.width * 0.125
} else if platformCount == 30 {
stage = 2
setTextures()
} else if platformCount >= 50 && platformCount < 60 {
stage = 0
setTextures()
xPosition = 184
} else if platformCount == 60 {
stage = 3
setTextures()
}
platformPhysics = SKPhysicsBody(rectangleOf: CGSize(width: platformTexture.size().width, height: platformTexture.size().height))
let platformLeft = SKSpriteNode(texture: platformTexture)
platformLeft.physicsBody = platformPhysics.copy() as? SKPhysicsBody
platformLeft.physicsBody?.isDynamic = false
platformLeft.physicsBody?.affectedByGravity = false
platformLeft.physicsBody?.collisionBitMask = 0
platformLeft.scale(to: CGSize(width: platformLeft.size.width * 3, height: platformLeft.size.height * 3))
platformLeft.zPosition = 20
platformLeft.name = "platform"
platformLeft.speed = platformSpeed
let platformRight = SKSpriteNode(texture: platformTexture)
platformRight.physicsBody = platformPhysics.copy() as? SKPhysicsBody
platformRight.physicsBody?.isDynamic = true
platformRight.physicsBody?.collisionBitMask = 0
platformRight.scale(to: CGSize(width: platformRight.size.width * 3, height: platformRight.size.height * 3))
platformRight.zPosition = 20
platformRight.name = "platform"
platformRight.speed = platformSpeed
let scoreNode = SKSpriteNode(color: UIColor.clear, size: CGSize(width: frame.width, height: 32))
scoreNode.physicsBody = SKPhysicsBody(rectangleOf: scoreNode.size)
scoreNode.physicsBody?.isDynamic = false
scoreNode.zPosition = 100
scoreNode.name = "scoreDetect"
scoreNode.speed = platformSpeed
let platformTrigger = SKSpriteNode(color: UIColor.orange, size: CGSize(width: frame.width, height: 4))
platformTrigger.physicsBody = SKPhysicsBody(rectangleOf: platformTrigger.size)
platformTrigger.physicsBody?.isDynamic = true
platformTrigger.physicsBody?.affectedByGravity = false
platformTrigger.physicsBody?.categoryBitMask = Collisions.detect
platformTrigger.physicsBody?.contactTestBitMask = Collisions.spawn
platformTrigger.physicsBody?.collisionBitMask = 0
platformTrigger.physicsBody?.usesPreciseCollisionDetection = true
platformTrigger.zPosition = 100
platformTrigger.name = "platformTrigger"
platformTrigger.speed = platformSpeed
let newNodes: Set<SKSpriteNode> = [platformLeft, platformRight, scoreNode, platformTrigger]
for node in newNodes {
platformGroup.insert(node)
}
let yPosition = spawnNode.position.y - transitionPlatform.size().height
let gapSize: CGFloat = -frame.size.width / 6
print(gapSize)
platformLeft.position = CGPoint(x: xPosition + platformLeft.size.width - gapSize, y: -yPosition)
platformRight.position = CGPoint(x: xPosition + gapSize, y: -yPosition)
scoreNode.position = CGPoint(x: frame.midX, y: platformLeft.position.y - platformLeft.size.height / 2)
platformTrigger.position = CGPoint(x: frame.midX, y: platformLeft.position.y)
print(platformLeft.position.y)
print(platformLeft.frame.midY)
let endPosition = frame.maxY + frame.midY
let moveAction = SKAction.moveBy(x: 0, y: endPosition, duration: 7)
for node in newNodes {
let moveSequence = SKAction.sequence([
moveAction,
SKAction.removeFromParent(),
SKAction.run {
self.platformGroup.remove(node)
}
])
addChild(node)
nodeArray.append(node)
node.run(moveSequence)
}
platformCount += 1
}
func startPlatforms() {
let create = SKAction.run { [unowned self] in
self.createPlatforms()
}
run(create)
}
func createBackground() {
for i in 0 ... 1 {
let background = backgroundPieces[i]
background.texture = backgroundTexture
background.anchorPoint = CGPoint(x: 0, y: 0)
background.zPosition = -5
background.size = CGSize(width: frame.size.width, height: frame.size.width * 2.5)
background.position = CGPoint(x: 0, y: background.size.height + (-background.size.height) + (-background.size.height * CGFloat(i)))
self.addChild(background)
nodeArray.append(background)
let scrollUp = SKAction.moveBy(x: 0, y: background.size.height, duration: 5)
let scrollReset = SKAction.moveBy(x: 0, y: -background.size.height, duration: 0)
let scrollLoop = SKAction.sequence([scrollUp, scrollReset])
let scrollForever = SKAction.repeatForever(scrollLoop)
background.run(scrollForever)
}
}
Does anybody have any suggestions on how I approach this or change it so it would work perfectly everytime?