我目前正在练习粒子系统,我想知道当点击按钮时,以下代码是否是停止和启动粒子的正确方法?
代码运行良好,我触摸开始按钮,粒子开始,我触摸停止按钮,粒子停止,但我不确定removeFromSuperLayer
是否是正确的使用方法。正如我所说,代码完成了我所需要的,但我只想确保粒子即使在调用removeFromSuperLayer
后也不会继续在后台运行,从而浪费资源。
- (IBAction)stopAnimation:(id)sender
{
[emitterLayer removeFromSuperlayer];
}
- (IBAction)startAnimation:(id)sender
{
[self particle];
}
-(void) particle
{
emitterLayer = [CAEmitterLayer layer];
emitterLayer.emitterPosition = CGPointMake(50 ,50);
emitterLayer.emitterZPosition = 10;
emitterLayer.emitterSize = CGSizeMake(10,10);
emitterLayer.emitterShape = kCAEmitterLayerSphere;
CAEmitterCell *emitterCell = [CAEmitterCell emitterCell];
emitterCell.scale = 0.1;
emitterCell.scaleRange = 0.2;
emitterCell.emissionRange = (CGFloat)M_PI_2;
emitterCell.lifetime = 10;
emitterCell.birthRate = 5;
emitterCell.velocity = 20;
emitterCell.velocityRange = 50;
emitterCell.yAcceleration = 0;
emitterCell.contents = (id)[[UIImage imageNamed:@"particleImage.png"] CGImage];
emitterLayer.emitterCells = [NSArray arrayWithObject:emitterCell];
[self.view.layer addSublayer:emitterLayer];
}
非常感谢
您可以使用一种方法,其中放入以下内容:
- (void)stopEmitting
{
self.emitterCell.birthRate = 0.0f;
}
这样,您就可以停止发射,而不必每次按下开始按钮时都删除并重新创建层。
要重新开始,只需执行:
- (void)startEmitting
{
self.emitterCell.birthRate = <VAlUE HERE (greater than 0)>;
}
希望这能有所帮助。
您可以更改emitterLayer本身的出生率,而不是更改每个emitterCells的出生率。
- (void)stopEmitting
{
self.emitterLayer.birthRate = 0;
}
- (void)startEmitting
{
self.emitterLayer.birthRate = 1;
}
这很有趣,但仅仅在方法中像self.emitterCell.birthRate = 0.0f;
这样修改birthRate并不能停止emitterCell,事实上,如果它附加而不是停止,换句话说,如果我将其更改为self.emitterCell.birthRate = 100;
,它会在现有粒子上再添加100个粒子。幸运的是,我找到了解决方案。
我基本上必须给我的emitterCell起一个名字emitterCell.name = @"_myCell";
,然后在我的stop方法中像[emitterLayer setValue:[NSNumber numberWithInteger:0] forKeyPath:@"emitterCells._myCell.birthRate"];
一样修改它,它就起作用了。
这就是我所做的工作。这是假设您的项目中已经有一个名为myImage的图像。
#import "SpriteViewController.h"
@implementation SpriteViewController
CAEmitterLayer *emitterLayer;
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (IBAction)stopAnimation:(id)sender
{
[emitterLayer setValue:[NSNumber numberWithInteger:0] forKeyPath:@"emitterCells._myCell.birthRate"]; // new code
}
- (IBAction)startAnimation:(id)sender
{
[self particle];
}
-(void) particle
{
emitterLayer = [CAEmitterLayer layer];
emitterLayer.emitterPosition = CGPointMake(50 ,50);
emitterLayer.emitterZPosition = 10;
emitterLayer.emitterSize = CGSizeMake(10,10);
emitterLayer.emitterShape = kCAEmitterLayerSphere;
CAEmitterCell *emitterCell = [CAEmitterCell emitterCell];
emitterCell.name = @"_myCell";// new code
emitterCell.scale = 0.1;
emitterCell.scaleRange = 0.2;
emitterCell.emissionRange = (CGFloat)M_PI_2;
emitterCell.lifetime = 10;
emitterCell.birthRate = 5;
emitterCell.velocity = 20;
emitterCell.velocityRange = 50;
emitterCell.yAcceleration = 0;
emitterCell.contents = (id)[[UIImage imageNamed:@"myImage.png"] CGImage];
emitterLayer.emitterCells = [NSArray arrayWithObject:emitterCell];
[self.view.layer addSublayer:emitterLayer];
}
@end