Currently doing a SoloProject for class and decided to study SpriteKit on my own. I decided to make a top-down zombie shooter and I have a lot of questions but so far these are the two main ones I can't seem to fix or find solution for.
Problem 1
Zombies slow down the closer they get to the target, If I increase the speed they just speed in from off the screen and still slowdown as they get closer (I've read somewhere putting that function in the update is bad but I still did it...)
I want to make it where they spawn with the speed of 3 and when the player moves closer or further away it stays at 3. (Currently using an analog stick code I found that was on Youtube to move my character around)
func zombieAttack() {
let location = player.position
for node in enemies {
let followPlayer = SKAction.move(to: player.position, duration: 3)
node.run(followPlayer)
//Aim
let dx = (location.x) - node.position.x
let dy = (location.y) - node.position.y
let angle = atan2(dy, dx)
node.zRotation = angle
//Seek
let velocityX = cos(angle) * 1
let velocityY = sin(angle) * 1
node.position.x += velocityX
node.position.y += velocityY
}
}
override func update(_ currentTime: TimeInterval) {
zombieAttack()
}
Problem 2
Also when multiple zombies get close to the players (function above) they start to spazz so I allowed them to overlap on top of each other to stop the spazzing.
I want to make it where they are more solid? if that is the right way to describe it. Basically I want them to huddle up around the player**.
If I add enemy to the collision it will spazz trying to get into the same position.
private func spawnZombie() {
let xPos = randomPosition(spriteSize: gameSpace.size)
let zombie = SKSpriteNode(imageNamed: "skeleton-idle_0")
zombie.position = CGPoint(x: -1 * xPos.x, y: -1 * xPos.y)
zombie.name = "Zombie\(zombieCounter)"
zombie.zPosition = NodesZPosition.enemy.rawValue
let presetTexture = SKTexture(imageNamed: "skeleton-idle_0.png")
zombie.physicsBody = SKPhysicsBody(texture: presetTexture, size: presetTexture.size())
zombie.physicsBody?.isDynamic = true
zombie.physicsBody?.affectedByGravity = false
zombie.physicsBody?.categoryBitMask = BodyType.enemy.rawValue
zombie.physicsBody?.contactTestBitMask = BodyType.bullet.rawValue
zombie.physicsBody?.collisionBitMask = BodyType.player.rawValue
zombie.zRotation = 1.5
zombie.setScale(0.2)
enemies.append(zombie)
zombieCounter += 1
run(SKAction.playSoundFileNamed("ZombieSpawn", waitForCompletion: false))
keepEnemiesSeperated() // ADDED FROM UPDATED EDIT*
addChild(zombie)
}
Let me know if I need to post more code or explain it better, I'm a five months in on learning Swift and have only a week and a half of SpriteKit experience and first time posting on StackOverFlow. Thanks all in advance!
EDIT: I am using a code I found from having a node follow at a constant speed but I don't think I'm doing it right since it is not working. I added the following code:
private func keepEnemiesSeparated() {
// Assign constrain
for enemy in enemies {
enemy.constraints = []
let distanceBetween = CGFloat(60)
let constraint = SKConstraint.distance(SKRange(lowerLimit: distanceBetween), to: enemy)
enemy.constraints!.append(constraint)
}
}
Problem 1, your zombie is moving based on time, not at a set speed. According to your code, he will always reach the player in 3 seconds. This means if he is 1 foot away, he takes 3 seconds. If he is 100 miles away, he takes 3 seconds. You need to use a dynamic duration if you are planning to use the moveTo SKAction based on the speed of the zombie. So if your zombie moves 10 points per second, you want to calculate the distance from zombie to player, and then divide by 10. Basically, your duration formula should be distance / speed
Problem 2, if you want the zombies to form a line, you are going to have to determine who the leading zombie is, and have each zombie follow the next leading zombie as opposed to all zombies following the player. Otherwise your other option is to not allow zombies to overlap, but again, you will still end up with more of a mosh pit then a line.
Related
In the SceneKit WWDC 2014, they have an example of a vortex field with this effect:
The particle system looks much like a tornato, as it spins inward with a hollow center.
However, the documentation for vortex fields have no information on how to achieve this effect. Right now, I have this:
// create the particle system
let exp = SCNParticleSystem()
exp.loops = true
exp.particleMass = 5
exp.birthRate = 10000
exp.emissionDuration = 10
exp.emitterShape = SCNTorus(ringRadius: 5, pipeRadius: 1)
exp.particleLifeSpan = 15
exp.particleVelocity = 2
exp.particleColor = UIColor.white
exp.isAffectedByPhysicsFields = true
scene.addParticleSystem(exp, transform: SCNMatrix4MakeRotation(0, 0, 0, 0))
// create the field
let field = SCNPhysicsField.vortex()
field.strength = -5
field.direction = SCNVector3(x: 0, y: 1, z: 0)
let fieldNode = SCNNode()
fieldNode.physicsField = field
scene.rootNode.addChildNode(fieldNode)
This creates this effect:
Where I am looking down at the particles rotating clockwise with a really big radius outwards. It looks nothing like a tornato effect. How can I create this effect?
You say tornato, I say tornado, let’s call the whole thing off...
The SceneKit WWDC 2014 demo/slides is a sample code project, so you can see for yourself how they made any of the effects you see therein. In this case, it looks like the “vortex” demo isn’t actually using the vortexField API, but instead the custom field API that lets you supply your own math in an evaluator block. (See the link for the code in that block.)
You might be able to get similar behavior without a custom field by combining a vortex (causes rotation only) with radial gravity (attracts inward) with linear gravity (attracts downward), or some other combination (possibly something involving electric charge). But you’d probably have to experiment with tweaking the parameters quite a bit.
If anyone is still interested in this topic - here is a Swift 5 implementation of that legendary tornado effect.
Here is an example function that will create your tornado.
func addTornadoPhysicsField() {
// Tornado Particles Field Example
guard let tornadoSystem = SCNParticleSystem(named: "tornado.scnp", inDirectory: nil) else { return }
let emitterGeometry = SCNTorus(ringRadius: 1.0, pipeRadius: 0.2)
emitterGeometry.firstMaterial?.transparency = 0.0
let fieldAndParticleNode = SCNNode(geometry: emitterGeometry)
fieldAndParticleNode.position = SCNVector3(0.0, 0.0, -20.0)
tornadoSystem.emitterShape = emitterGeometry
fieldAndParticleNode.addParticleSystem(tornadoSystem)
yourScene.rootNode.addChildNode(fieldAndParticleNode)
// Tornado
let worldOrigin = SCNVector3Make(fieldAndParticleNode.worldTransform.m41,
fieldAndParticleNode.worldTransform.m42,
fieldAndParticleNode.worldTransform.m43)
let worldAxis = simd_float3(0.0, 1.0, 0.0) // i.Ex. the Y axis
// Custom Field (Tornado)
let customVortexField = SCNPhysicsField.customField(evaluationBlock: { position, velocity, mass, charge, time in
let l = simd_float3(worldOrigin.x - position.x, 1.0, worldOrigin.z - position.z)
let t = simd_cross(worldAxis, l)
let d2: Float = l.x * l.x + l.z * l.z
let vs: Float = 27 / sqrt(d2) // diameter, the bigger the value the wider it becomes (Apple Default = 20)
let fy: Float = 1.0 - Float((min(1.0, (position.y / 240.0)))) // rotations, a higher value means more turn arounds (more screwed, Apple Default = 15.0))
return SCNVector3Make(t.x * vs + l.x * 10 * fy, 0, t.z * vs + l.z * 10 * fy)
})
customVortexField.halfExtent = SCNVector3Make(100, 100, 100)
fieldAndParticleNode.physicsField = customVortexField // Attach the Field
}
Additional Configuration Options:
Finally all this can result in something like that:
Note: if you would like to move your static tornado almost like a real tornado, you will have to find a way to re-apply the physics field for each rendererd frame. If you don't, the world origin used in the evaluation block will not move and it will distort your tornado.
Note: You can also split the particle/field node into two different nodes that moves independently from each other. Constrain the field node to the position of the particle node and play around with the influence factor (still need to re-apply the field each frame)
For more information on Custom Fields check out here.
I want to create an eyeball that follows the user. In this sense, the eye should follow the position of the user but should only be able to move within certain bounds (The eye socket). The code I wrote below works, but its very choppy.
if(dist <= socketRadius - self.aEye.size.width/2.2){
lastPosition = self.aEye.position
self.aEye.physicsBody?.velocity = CGVector(dx:theVec.dx * eyeMoveSpeed, dy:theVec.dy * eyeMoveSpeed)
}
else{
let toCenterVector = normalizeVector( CGVector(dx:(self.socket.position.x - self.aEye.position.x), dy:(self.socket.position.y - self.aEye.position.y)*3 ))
self.aEye.physicsBody?.velocity = toCenterVector
print(toCenterVector)
print("Out")
}
(dist is the distance from the eyeball to the eyesocket center)
Is there a way to have a smooth flow of the eyeball around its socket to follow the user's position?
You can use SKConstraints to achieve this. Something like:
let rangeToCenterSprite = SKRange(lowerLimit: 80, upperLimit: 90)
var distanceConstraint: SKConstraint
distanceConstraint = SKConstraint.distance(rangeToCenterSprite, toNode: SpriteNodeInEyeCenter)
EyeBallSprite.constraints = [distanceConstraint]
Alright so I'm building a sprite kit game where I need to delay an enemy spawn func repeatedly.
I've managed to generate random Doubles using this function:
func randomDelay()->Double {
var randLower : UInt32 = 1
var randUpper : UInt32 = 50
var randDelayTime = arc4random_uniform(randUpper - randLower) + randLower
var randDelayTimer = Double(randDelayTime) / 10
//var randDelay = randDelayTimer * Double(NSEC_PER_SEC)
//var newTime = dispatch_time(DISPATCH_TIME_NOW, Int64(randDelay))
println(randDelayTimer)
return randDelayTimer
}
I know this works because I printed randDelayTimer out several times and it does in fact generate random Doubles.
Here is where I try to spawn my enemies after the random delay repeatedly:
runAction(SKAction.repeatActionForever(
SKAction.sequence([
SKAction.waitForDuration(NSTimeInterval(randomDelay())),
SKAction.runBlock({self.spawnEnemy1()})))
This works, but only the first time it is run. Whatever random Double is generated by randomDelay() the FIRST TIME the sequence is cycled through is applied to every enemy that is spawned after that. For example if when the game is run, randomDelay() = 3.5, a 3.5 sec delay is repeated forever.
I know that randomDelay() is only being run that first time also because nothing is printed to the console after the first time.
How can I fix this?
You should use the following static method on SKAction:
class func waitForDuration(_ sec: NSTimeInterval,
withRange durationRange: NSTimeInterval) -> SKAction
From the SKAction documentation:
Each time the action is executed, the action computes a new random value for the duration. The duration may vary in either direction by up to half of the value of the durationRange parameter.
In your case, with a minimum duration of 1 second and a maximum duration of 50 seconds, you'd use:
// A mean wait of 25.5 seconds. The wait can vary by 24.5 seconds above and below the mean.
let waitAction = SKAction.waitForDuration(25.5, withRange: 49)
It's a little inconvenient to manually calculate the mean and range from the maximum and minimum waiting time, so you could use an extension on SKAction to do the work for you:
extension SKAction {
static func waitForDuration(minimum min: NSTimeInterval, maximum max: NSTimeInterval) -> SKAction {
return SKAction.waitForDuration((max + min) / 2, withRange: abs(max - min))
}
}
Usage:
let waitAction = SKAction.waitForDuration(minimum: 1, maximum: 50)
So I have this Swift code using SpriteKit:
let ballX = ball.position.x
let ballY = ball.position.y
let ballR = ball.size.width / 2
let sceneW = self.size.width
let sceneH = self.size.height
if ballY >= sceneH - ballR - 3 {
framesOnTop += 1
} else {
framesOnTop = 0
}
if framesOnTop > 2 {
// Some code here
}
I have the ball node (SKSpriteNode) that can hit the ceiling and bounce back (scene has no gravity) but sometimes it can hit the ceiling at a very steep angle and get stuck in an infinite loop, left right left right left right. In the if statement that says framesOnTop > 2 I am successfully detecting when it gets stuck, and I want to make it bounce back down at the right angle with physicsBody.applyImpulse. But to do this I need the velocity from before it gets stuck (~5 frames before). Is this possible or is there a better way to fix it?
I am trying to have my Label to increment +1 every time a sprite makes contact with a Contact node, but it increments by large numbers like +23. I think what is happening is that its taking into account every millisecond that the sprite is touching the node, but i don't know how to fix it.
Here is my Label node code within DidMoveToView:
score = 0
scoreLabelNode = SKLabelNode(fontNamed:"[z] Arista Light")
scoreLabelNode.position = CGPointMake(self.frame.size.width/2, self.frame.size.height/4)
scoreLabelNode.zPosition = 100
scoreLabelNode.fontSize = 500
scoreLabelNode.alpha = 0.03
scoreLabelNode.text = String(score)
self.addChild(scoreLabelNode)
here is my contact node:
var contactNode = SKNode()
contactNode.position = CGPoint(x: self.frame.size.width + asteroidTexture.size().height / 15 + rocket.size.width, y: 0.0)
contactNode.physicsBody = SKPhysicsBody(rectangleOfSize: CGSizeMake( asteroid.size.width/16, self.frame.size.height*2 ))
contactNode.physicsBody?.dynamic = false
contactNode.physicsBody?.categoryBitMask = scoreCategory
contactNode.physicsBody?.contactTestBitMask = rocketCategory
contactNode.runAction(asteroidsMoveAndRemove)
moving.addChild(contactNode)
and here is my code where when my rocket sprite makes contact with the contactNode it increments:
func didBeginContact(contact: SKPhysicsContact) {
if moving.speed > 0 {
if ( contact.bodyA.categoryBitMask & scoreCategory ) == scoreCategory || ( contact.bodyB.categoryBitMask & scoreCategory ) == scoreCategory {
// Rocket has contact with score entity
score++
scoreLabelNode.text = String(score)
println("HIT")
}
else{
gameOver()
}
}
'moving' is when my asteroid sprites are moving, the contact nodes move with it
It's probably not every millisecond, but instead every frame, and that's why you likely end up with numbers like +23 (The collision is taking place for a 1/3 of a second and if it's running at 60 FPS that is about 20 or so frames).
One thing you could do is subclass SKNode into an actual ContactNode class that has a property hasBeenStruck that is initially set to false or something to that extent.
Then when you check contact, you first check to see if hasBeenStruck is false. If it is, register the hit and update the score and then set that ContactNode's hasBeenStruck property to true. This way, on the next 20 or so checks to see if contact has happened, it won't keep updating the label because the if condition has failed.
However, if your game allows a user to hit the same ContactNode twice and get score both times, this isn't a complete solution. If that is the case, you could use a timer or "invincibility" period for the given ContactNode.