CAEmitterCell - 緩慢的星星或燈光效果

Question

我正在玩CAEmitterCell，但大多數效果都非常快，就像煙花一樣。 但我想有一個像你在這裏看到的緩慢的「星星」效果www.findyourwaytooz.com

我該怎麼用CAEmitterCell做到這一點？

謝謝:)

Answer 1

我有一個使用以下設置爲發射一個項目，它非常精確地模仿什麼，我認爲你的意思是：

//set ref to the layer 
starsEmitter = (CAEmitterLayer*)self.layer; //2 

//configure the emitter layer 
starsEmitter.emitterPosition = CGPointMake(160, 240); 
starsEmitter.emitterSize = CGSizeMake(self.superview.bounds.size.width,self.superview.bounds.size.height); 
NSLog(@"width = %f, height = %f", starsEmitter.emitterSize.width, starsEmitter.emitterSize.height); 
starsEmitter.renderMode = kCAEmitterLayerPoints; 
starsEmitter.emitterShape = kCAEmitterLayerRectangle; 
starsEmitter.emitterMode = kCAEmitterLayerUnordered; 

CAEmitterCell* stars = [CAEmitterCell emitterCell]; 
stars.birthRate = 0; 
stars.lifetime = 10; 
stars.lifetimeRange = 0.5; 
stars.color = [[UIColor colorWithRed:255 green:255 blue:255 alpha:0] CGColor]; 
stars.contents = (id)[[UIImage imageNamed:@"particle.png"] CGImage]; 
stars.velocityRange = 500; 
stars.emissionRange = 360; 
stars.scale = 0.2; 
stars.scaleRange = 0.1; 
stars.alphaRange = 0.3; 
stars.alphaSpeed = 0.5;  
[stars setName:@"stars"]; 

//add the cell to the layer and we're done 
starsEmitter.emitterCells = [NSArray arrayWithObject:stars]; 

我上傳的樣本項目的GitHub ：SimpleCAEmitterLayer