Using SKEmitterNode in SprikeKit, is it possible to change the speed/alpha of particles after they are released?
What I'm looking for is a particle emitter that emits particles, those particles are static but after x amount of seconds, they start moving. Is this possible?
I wrote the answer in swift before i saw the objective-c tag.. hope thats okay.
heres my particle file so you can try it yourself:
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let emitter = SKEmitterNode(fileNamed: "fire")
emitter.position = CGPoint(x: self.size.width/2, y: self.size.height/2)
let time = CGFloat(2)
emitter.runAction(SKAction.sequence([
SKAction.waitForDuration(3),
SKAction.customActionWithDuration(NSTimeInterval(time), actionBlock: {
_, t in
let timePercentage = t / time // percentage of elapsed time
let maxSpeed = CGFloat(200)
emitter.particleSpeed = timePercentage * maxSpeed
})
]))
self.addChild(emitter)
this code will allow you to animate your emitter's properties over time.
Related
I'm trying to build a small spriteKitGame. I have been trying to use the function to move a couple of tank sprite nodes to a specific point.
Attached below is the code snippet.
let tankSpawn = CGPoint(x: self.size.width , y: 70);
tank.position = tankSpawn;
tank.zPosition = 3.0;
let targetPoint = CGPoint(x: -tank.size.width/2, y: tank.position.y);
let actionMove = SKAction.move(to: targetPoint, duration: TimeInterval(tankMoveDuration))
This is my result. They are spawning at the correct point ( 70units high ), but are going down as shown.
I want them to go in a straight line. I set the target points y as a constant. I have no idea why they are going to wards some bottom source.
I have similar code for planes that spawn above( which are working perfectly ).
let plane = SKSpriteNode(imageNamed: "SpaceShip");
let planeMoveDuration = 3.0
let planeSpawn = CGPoint(x: self.size.width , y: self.size.height/2);
plane.position = planeSpawn;
plane.zPosition = 3.0;
let actionMove = SKAction.move(to: CGPoint(x: -plane.size.width/2, y: plane.position.y), duration: TimeInterval(planeMoveDuration))
I have no idea what my mistake here is.
I have tried changing the y co ordinate of the target to tank.position.y, but it doesn't work.
Are they falling under gravity? A sprite-kit scene with physics bodies will have gravity and things will fall unless you take specific action to avoid this.
It's easily done - you're developing your game, you have basic elements on screen and movement etc is all working well, then you want to add some collision detection so you add physicsBodies and then whoosh - where'd my sprites go?
I want to create a particle system on iOS using sprite kit where I define the colour of each individual particle. As far as I can tell this isn't possible with the existing SKEmitterNode.
It seems that best I can do is specify general behaviour. Is there any way I can specify the starting colour and position of each particle?
This can give you a basic idea what I was meant in my comments. But keep in mind that it is untested and I am not sure how it will behave if frame rate drops occur.
This example creates 5 particles per second, add them sequentially (in counterclockwise direction) along the perimeter of a given circle. Each particle will have different predefined color. You can play with Settings struct properties to change the particle spawning speed or to increase or decrease number of particles to emit.
Pretty much everything is commented, so I guess you will be fine:
Swift 2
import SpriteKit
struct Settings {
static var numberOfParticles = 30
static var particleBirthRate:CGFloat = 5 //Means 5 particles per second, 0.2 means one particle in 5 seconds etc.
}
class GameScene: SKScene {
var positions = [CGPoint]()
var colors = [SKColor]()
var emitterNode:SKEmitterNode?
var currentPosition = 0
override func didMoveToView(view: SKView) {
backgroundColor = .blackColor()
emitterNode = SKEmitterNode(fileNamed: "rain.sks")
if let emitter = emitterNode {
emitter.position = CGPoint(x: CGRectGetMidX(frame), y: CGRectGetMidY(frame))
emitter.particleBirthRate = Settings.particleBirthRate
addChild(emitter)
let radius = 50.0
let center = CGPointZero
for var i = 0; i <= Settings.numberOfParticles; i++ {
//Randomize color
colors.append(SKColor(red: 0.78, green: CGFloat(i*8)/255.0, blue: 0.38, alpha: 1))
//Create some points on a perimeter of a given circle (radius = 40)
let angle = Double(i) * 2.0 * M_PI / Double(Settings.numberOfParticles)
let x = radius * cos(angle)
let y = radius * sin(angle)
let currentParticlePosition = CGPointMake(CGFloat(x) + center.x, CGFloat(y) + center.y)
positions.append(currentParticlePosition)
if i == 1 {
/*
Set start position for the first particle.
particlePosition is starting position for each particle in the emitter's coordinate space. Defaults to (0.0, 0,0).
*/
emitter.particlePosition = positions[0]
emitter.particleColor = colors[0]
self.currentPosition++
}
}
// Added just for debugging purposes to show positions for every particle.
for particlePosition in positions {
let sprite = SKSpriteNode(color: SKColor.orangeColor(), size: CGSize(width: 1, height: 1))
sprite.position = convertPoint(particlePosition, fromNode:emitter)
sprite.zPosition = 2
addChild(sprite)
}
let block = SKAction.runBlock({
// Prevent strong reference cycles.
[unowned self] in
if self.currentPosition < self.positions.count {
// Set color for the next particle
emitter.particleColor = self.colors[self.currentPosition]
// Set position for the next particle. Keep in mind that particlePosition is a point in the emitter's coordinate space.
emitter.particlePosition = self.positions[self.currentPosition++]
}else {
//Stop the action
self.removeActionForKey("emitting")
emitter.particleBirthRate = 0
}
})
// particleBirthRate is a rate at which new particles are generated, in particles per second. Defaults to 0.0.
let rate = NSTimeInterval(CGFloat(1.0) / Settings.particleBirthRate)
let sequence = SKAction.sequence([SKAction.waitForDuration(rate), block])
let repeatAction = SKAction.repeatActionForever(sequence)
runAction(repeatAction, withKey: "emitting")
}
}
}
Swift 3.1
import SpriteKit
struct Settings {
static var numberOfParticles = 30
static var particleBirthRate:CGFloat = 5 //Means 5 particles per second, 0.2 means one particle in 5 seconds etc.
}
class GameScene: SKScene {
var positions = [CGPoint]()
var colors = [SKColor]()
var emitterNode: SKEmitterNode?
var currentPosition = 0
override func didMove(to view: SKView) {
backgroundColor = SKColor.black
emitterNode = SKEmitterNode(fileNamed: "rain.sks")
if let emitter = emitterNode {
emitter.position = CGPoint(x: frame.midX, y: frame.midY)
emitter.particleBirthRate = Settings.particleBirthRate
addChild(emitter)
let radius = 50.0
let center = CGPoint.zero
for var i in 0...Settings.numberOfParticles {
//Randomize color
colors.append(SKColor(red: 0.78, green: CGFloat(i * 8) / 255.0, blue: 0.38, alpha: 1))
//Create some points on a perimeter of a given circle (radius = 40)
let angle = Double(i) * 2.0 * Double.pi / Double(Settings.numberOfParticles)
let x = radius * cos(angle)
let y = radius * sin(angle)
let currentParticlePosition = CGPoint.init(x: CGFloat(x) + center.x, y: CGFloat(y) + center.y)
positions.append(currentParticlePosition)
if i == 1 {
/*
Set start position for the first particle.
particlePosition is starting position for each particle in the emitter's coordinate space. Defaults to (0.0, 0,0).
*/
emitter.particlePosition = positions[0]
emitter.particleColor = colors[0]
self.currentPosition += 1
}
}
// Added just for debugging purposes to show positions for every particle.
for particlePosition in positions {
let sprite = SKSpriteNode(color: SKColor.orange, size: CGSize(width: 1, height: 1))
sprite.position = convert(particlePosition, from: emitter)
sprite.zPosition = 2
addChild(sprite)
}
let block = SKAction.run({
// Prevent strong reference cycles.
[unowned self] in
if self.currentPosition < self.positions.count {
// Set color for the next particle
emitter.particleColor = self.colors[self.currentPosition]
// Set position for the next particle. Keep in mind that particlePosition is a point in the emitter's coordinate space.
emitter.particlePosition = self.positions[self.currentPosition]
self.currentPosition += 1
} else {
//Stop the action
self.removeAction(forKey: "emitting")
emitter.particleBirthRate = 0
}
})
// particleBirthRate is a rate at which new particles are generated, in particles per second. Defaults to 0.0.
let rate = TimeInterval(CGFloat(1.0) / Settings.particleBirthRate)
let sequence = SKAction.sequence([SKAction.wait(forDuration: rate), block])
let repeatAction = SKAction.repeatForever(sequence)
run(repeatAction, withKey: "emitting")
}
}
}
Orange dots are added just for debugging purposes and you can remove that part if you like.
Personally I would say that you are overthinking this, but I might be wrong because there is no clear description of what you are trying to make and how to use it. Keep in mind that SpriteKit can render a bunch of sprites in a single draw call in very performant way. Same goes with SKEmitterNode if used sparingly. Also, don't underestimate SKEmitterNode... It is very configurable actually.
Here is the setup of Particle Emitter Editor:
Anyways, here is the final result:
Note that nodes count comes from an orange SKSpriteNodes used for debugging. If you remove them, you will see that there is only one node added to the scene (emitter node).
What you want is completely possible, probably even in real time. Unfortunately to do such a thing the way you describe with moving particles as being a particle for each pixel would be best done with a pixel shader. I don't know of a clean method that would allow you to draw on top of the scene with a pixel shader otherwise all you would need is a pixel shader that takes the pixels and moves them out from the center. I personally wouldn't try to do this unless I built the game with my own custom game engine in place of spritekit.
That being said I'm not sure a pixel per pixel diffusion is the best thing in most cases. Expecially if you have cartoony art. Many popular games will actually make sprites for fragments of the object they expect to shader. So like if it's an airplane you might have a sprite for the wings with perhaps even wires hanging out of this. Then when it is time to shatter the plane, remove it from the scene and replace the area with the pieces in the same shape of the plane... Sorta like a puzzle. This will likely take some tweaking. Then you can add skphysicsbodies to all of these pieces and have a force push them out in all directions. Also this doesn't mean that each pixel gets a node. I would suggest creatively breaking it into under 10 pieces.
And as whirlwind said you could all ways get things looking "like" it actually disintegrated by using an emitter node. Just make the spawn area bigger and try to emulate the color as much as possible. To make the ship dissappear you could do a fade perhaps? Or Mabye an explosion sprite over it? Often with real time special effects and physics, or with vfx it is more about making it look like reality then actually simulating reality. Sometimes you have to use trickery to get things to look good and run real-time.
If you want to see how this might look I would recommend looking at games like jetpac joyride.
Good luck!
I am building a ios game with swift and I have run into a bit of a problem. I am trying to spawn balls from the top of the screen and have them come down towards the ground. They are supposed to have random x values and go down at random rates but instead of spawning on the screen the nodes spawn on an x value which is not encompassed by the screen. Please help me as I think I have done everything right.
Here is the code for my addball function...
func addBall(){
//create ball sprite
var ball = SKSpriteNode(imageNamed: "ball.png")
//create physics for ball
ball.physicsBody = SKPhysicsBody(rectangleOfSize: ball.size) // 1
ball.physicsBody?.dynamic = true // 2
ball.physicsBody?.categoryBitMask = PhysicsCategory.Ball // 3
ball.physicsBody?.contactTestBitMask = PhysicsCategory.Person & PhysicsCategory.Ground
ball.physicsBody?.collisionBitMask = PhysicsCategory.None // 5
//generate random postion along x axis for ball to spawn
let actualX = random(min:ball.frame.size.width/2+1, max: self.frame.size.width - ball.frame.size.width/2-1)
println(actualX)
//set balls positon
ball.position = CGPoint(x: actualX, y: size.height - ball.size.width/2)
//add ball to scene
addChild(ball)
//determine speed of ball
let actualDuration = random(min: CGFloat(3.0), max: CGFloat(5.0))
//create movement actions
let actionMove = SKAction.moveTo(CGPoint(x:actualX, y: -ball.size.width/2), duration: NSTimeInterval(actualDuration))
let actionMoveDone = SKAction.removeFromParent()
ball.runAction(SKAction.sequence([actionMove, actionMoveDone]), withKey: "action")
}
here is the code for my random functions
func random() -> CGFloat {
return CGFloat(Float(arc4random()) / 0xFFFFFFFF)
}
func random(#min: CGFloat, max: CGFloat) -> CGFloat {
return random() * (max - min) + min
}
The problem here is that your SKScene likely takes up much more space than the screen of your device. Thus, when you calculate a random value using the whole scene, some of the time the ball will spawn in the area of the scene not visible to you.
The two main properties that control the scene's size are its size and scaleMode properties. The scaleMode property relates to how the scene is mapped. Unless you initialized and presented this scene yourself, you can check the scaleMode in your view controller. It will likely be set to aspectFill, which according to Apple means:
The scaling factor of each dimension is calculated and the larger of the two is chosen. Each axis of the scene is scaled by the same scaling factor. This guarantees that the entire area of the view is filled but may cause parts of the scene to be cropped.
If you don't like this, there are other scaleModes. However, in most cases this mode would actually be preferable since SpriteKit's internal scaling is able to make universal apps. If this is fine for you, then the easiest thing to do is set hardcoded values for something like the spawn locations for your ball node.
Im making a simple game with apple's SpriteKit and Swift and have encountered a problem. Im trying to get a paddle node (paddle) to rotate continuously around a fixed node (anchorNode) inside a circle; however, I cannot figure out how to make the paddle node (paddle) keep rotating around the fixed point node (anchorNode) because of the constrains in the SKAction.rotateByAngle statement making it end after a certain amount of time / rotation.
Any help is greatly appreciated!
Here is my code for reference:
//Setting up anchor Node
anchorNode.position = CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame))
anchorNode.size.height = (self.frame.size.height / 1000)
anchorNode.size.width = anchorNode.size.height
self.addChild(anchorNode)
//Setting up achor Node's physucs
anchorNode.physicsBody = SKPhysicsBody(circleOfRadius: (circle.frame.size.height / 1000))
anchorNode.physicsBody?.dynamic = false
anchorNode.physicsBody?.affectedByGravity = false
anchorNode.physicsBody?.friction = 0
//Making the anchor Node rotate
let rotate = SKAction.rotateByAngle(CGFloat(3.14), duration: NSTimeInterval(1.5))
anchorNode.runAction(rotate)
//Setting up the paddle node
paddle.position = CGPointMake((circle.frame.width / 2), 0)
paddle.size.height = (self.frame.size.height / 50)
paddle.size.width = (self.frame.size.width / 7)
anchorNode.addChild(paddle)
Try adding this code.
override func update(currentTime: NSTimeInterval) {
//How to make it spin
let speed = CGFloat(5)
let degreeRotation = CDouble(speed) * M_PI / 180
paddle.zRotation -= CGFloat(degreeRotation)
}
Using this fixed my problem:
anchorNode.runAction(SKAction.repeatActionForever(rotate))
Thanks, User:
0x141E
So I'm playing around and slowly making my first iOS game. I'm trying to get my sprite object to set out a straight path angled towards the location of the player (which is where the user last touched).
The code I have makes the bee move towards the player and stop when it gets to it, instead of going from one side of the screen, through the player and off the other side of the screen.
var beeSpeed = 2.0
var moveAccross = SKAction.moveTo(CGPointMake(player.position.x,player.position.y), duration:beeSpeed)
badBee.runAction(moveAccross)
I will be having many objects constantly spawning that should all set their path once to the player location at the time they spawn.
Any help would be great,
I think I figured it out, if anyone could check my code and make sure it's doing the right thing that would be great :)
let actionMove = SKAction.moveTo(CGPoint(x: player.position.x-player.position.x-bee.size.width, y: player.position.y), duration: NSTimeInterval(actualDuration))
let actionMoveDone = SKAction.removeFromParent()
bee.runAction(SKAction.sequence([actionMove, actionMoveDone]))
You have to calculate the slope from the spawning point to the player and then interpolate to somewhere outside the screen.
func add(location:CGPoint)
{
let bee = SKSpriteNode(color: UIColor.redColor(), size: CGSizeMake(10, 10))
bee.name = "Bee"
bee.position = location
self.addChild(bee)
let slopeToPlayer = (bee.position.y - player.position.y) / (bee.position.x - player.position.x)
let constant = bee.position.y - slopeToPlayer * bee.position.x
let finalX : CGFloat = bee.position.x < player.position.x ? 500.0 : -500.0 // Set it to somewhere outside screen size
let finalY = constant + slopeToPlayer * finalX
let distance = (bee.position.y - finalY) * (bee.position.y - finalY) + (bee.position.x - finalX) * (bee.position.x - finalX)
let beeSpeed : CGFloat = 100.0
let timeToCoverDistance = sqrt(distance) / beeSpeed
let moveAction = SKAction.moveTo(CGPointMake(finalX, finalY), duration: NSTimeInterval(timeToCoverDistance))
let removeAction = SKAction.runBlock { () -> Void in
bee.removeFromParent()
println("removed")
}
bee.runAction(SKAction.sequence([moveAction,removeAction]))
}