粒子雪花效果

粒子雪花效果

效果

源码

https://github.com/YouXianMing/Animations

//
//  EmitterSnowController.m
//  Animations
//
//  Created by YouXianMing on 15/12/21.
//  Copyright  2015年 YouXianMing. All rights reserved.
//

#import "EmitterSnowController.h"

@interface EmitterSnowController ()

@property (nonatomic, strong) CALayer   *movedMask;

@end

@implementation EmitterSnowController

- (void)viewDidLoad {

    [super viewDidLoad];
}

- (void)setup {

    [super setup];

    self.backgroundView.backgroundColor = [UIColor blackColor];

    // 创建粒子Layer
    CAEmitterLayer *snowEmitter = [CAEmitterLayer layer];

    // 粒子发射位置
    snowEmitter.emitterPosition = CGPointMake(120,0);

    // 发射源的尺寸大小
    snowEmitter.emitterSize  = self.contentView.bounds.size;

    // 发射模式
    snowEmitter.emitterMode  = kCAEmitterLayerSurface;

    // 发射源的形状
    snowEmitter.emitterShape = kCAEmitterLayerLine;

    // 创建雪花类型的粒子
    CAEmitterCell *snowflake = [CAEmitterCell emitterCell];

    // 粒子的名字
    snowflake.name = @"snow";

    // 粒子参数的速度乘数因子
    snowflake.birthRate = 20.0;
    snowflake.lifetime  = 120.0;

    // 粒子速度
    snowflake.velocity =10.0;

    // 粒子的速度范围
    snowflake.velocityRange = 10;

    // 粒子y方向的加速度分量
    snowflake.yAcceleration = 2;

    // 周围发射角度
    snowflake.emissionRange = 0.5 * M_PI;

    // 子旋转角度范围
    snowflake.spinRange = 0.25 * M_PI;
    snowflake.contents  = (id)[[UIImage imageNamed:@"snow"] CGImage];

    // 设置雪花形状的粒子的颜色
    snowflake.color      = [[UIColor whiteColor] CGColor];
    snowflake.redRange   = 2.f;
    snowflake.greenRange = 2.f;
    snowflake.blueRange  = 2.f;

    snowflake.scaleRange = 0.6f;
    snowflake.scale      = 0.7f;

    snowEmitter.shadowOpacity = 1.0;
    snowEmitter.shadowRadius  = 0.0;
    snowEmitter.shadowOffset  = CGSizeMake(0.0, 0.0);

    // 粒子边缘的颜色
    snowEmitter.shadowColor  = [[UIColor whiteColor] CGColor];

    // 添加粒子
    snowEmitter.emitterCells = @[snowflake];

    // 将粒子Layer添加进图层中
    [self.contentView.layer addSublayer:snowEmitter];

    // 形成遮罩
    UIImage *image      = [UIImage imageNamed:@"alpha"];
    _movedMask          = [CALayer layer];
    _movedMask.frame    = (CGRect){CGPointZero, image.size};
    _movedMask.contents = (__bridge id)(image.CGImage);
    _movedMask.position = self.contentView.center;
    snowEmitter.mask    = _movedMask;

    // 拖拽的View
    UIView *dragView = [[UIView alloc] initWithFrame:(CGRect){CGPointZero, image.size}];
    dragView.center  = self.contentView.center;
    [self.contentView addSubview:dragView];

    // 给dragView添加拖拽手势
    UIPanGestureRecognizer *recognizer = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(handlePan:)];
    [dragView addGestureRecognizer:recognizer];
}

- (void)handlePan:(UIPanGestureRecognizer *)recognizer {

    // 拖拽
    CGPoint translation = [recognizer translationInView:self.contentView];
    recognizer.view.center = CGPointMake(recognizer.view.center.x + translation.x,
                                         recognizer.view.center.y + translation.y);
    [recognizer setTranslation:CGPointMake(0, 0) inView:self.contentView];

    // 关闭CoreAnimation实时动画绘制(核心)
    [CATransaction setDisableActions:YES];
    _movedMask.position = recognizer.view.center;
}

@end

细节