Barebones CAEmitterLayer aka Particle Effects
CAEmitterLayer: use to create particle effects. Each particle is an instance of CAEmitterCell. (10.6) – cocoadevcentral
How could you not be intrigued? Particle Effects! Well I’ve always been interested in Particle Generators, and there’s one right here in Snow Leopard. How exciting. /claps.
I recently took a look at the Fire and Fireworks sample code that Apple and was duly impressed by what Core Animation provides for so little cost both code-wise and CPU resources. So I decided to write the simplest – barebones – CAEmitterLayer code where I was only dependant on the NSView it draws on.
There’s no fancy-pants stuff going on here, just a raw, simple, single particle effect. But it gives you a great perspective on how it works and the minimal code required to have a great particle animation.
If you’re starting afresh you’re going to need to tell your project that we want to use Core Animation so:
- Right click the Frameworks > Linked Frameworks on the left,
- Add > Existing Frameworks…
- Scroll to QuartzCore.framework > Add,
- And make sure your ParticleController header file contains
#import <QuartzCore/QuartzCore.h>.
Looking at CAEmitterLayer briefly (and ignoring setting up Interface Builder & the Nib) in our header file we simply need a CAEmitterLayer:
IBOutlet NSView *view; CALayer *rootLayer; CAEmitterLayer *emitter; |
Where as the implementation file is going to need a whole lot of data for the Emitter plus we need to create a CAEmitterCell for the particle itself.
//Create the emitter layer emitter = [CAEmitterLayer layer]; emitter.emitterPosition = CGPointMake(CGRectGetMidX(rootLayer.bounds), CGRectGetMidY(rootLayer.bounds)); emitter.emitterMode = kCAEmitterLayerOutline; emitter.emitterShape = kCAEmitterLayerCircle; emitter.renderMode = kCAEmitterLayerAdditive; emitter.emitterSize = CGSizeMake(50 * multiplier, 0); //Create the emitter cell CAEmitterCell* particle = [CAEmitterCell emitterCell]; particle.emissionLongitude = M_PI; particle.birthRate = multiplier * 1000.0; particle.lifetime = multiplier; particle.lifetimeRange = multiplier * 0.35; particle.velocity = 180; particle.velocityRange = 130; particle.emissionRange = 1.1; particle.scaleSpeed = 0.3; CGColorRef color = CGColorCreateGenericRGB(0.3, 0.4, 0.9, 0.10); particle.color = color; CGColorRelease(color); particle.contents = (id) [self CGImageNamed:@"spark.png"]; |
For the complete implementation file or the complete project please feel free to grab the source code from the bitbucket project.
Tags: CAEmitterLayer, Core Animation
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