Effect – 反復横跳び

時間tにおけるx,yおよび縮尺を考える。

１秒間で往復する

左右：初期位置は0で -10 ~ 10の範囲

上下：初期位置は10で    0 ~ 10の範囲

縮尺：初期位置で100% 端では 80%くらいに縮める

式

x = 20 * sin(2πt)

y = abs( 20 * sin(2πt) )

ratio = 0.2 * abs(cos(2πt)) + 0.8

サンプルコード

[ EffectKun.h ]

@interface EffectKun : NSObject 

+ (void)jump:(UIView*)view origin:(CGRect)frame time:(float)time;

@end

[ EffectKun.m ]

@implementation EffectKun

+ (void)jump:(UIView*)view origin:(CGRect)frame time:(float)time

{

    float x = 20 * sinf(2.0 * M_PI * time) + frame.origin.x;

    float y = fabsf(20 * sinf(2.0 * M_PI * time)) + frame.origin.y;

    float ratio = 0.2 * fabsf(cosf(2.0 * M_PI * time)) + 0.8;

    

    view.center = CGPointMake(x, y);

    view.transform = CGAffineTransformMakeScale(1.0, ratio);

}

@end

[ ViewController.m ]

#import “ViewController.h”

#import “EffectKun.h”

#import <QuartzCore/QuartzCore.h>

@interface ViewController () {

    CADisplayLink *timer;

    UIView *mark;

    CGRect origin;

}

@end

@implementation ViewController

– (void)viewDidLoad

{

    [super viewDidLoad];

    

    mark = [[UIView alloc] initWithFrame:CGRectMake(50, 100, 30, 30)];

    mark.backgroundColor = [UIColor purpleColor];

    [self.view addSubview:mark];

    

    origin = mark.frame;

    

    // loop

    timer = [CADisplayLink displayLinkWithTarget:self selector:@selector(update:)];

    [timer addToRunLoop:[NSRunLoop currentRunLoop] forMode:NSDefaultRunLoopMode];

}

– (void)update:(CADisplayLink*)sender

{

    [EffectKun jump:mark origin:origin time:sender.timestamp];

}

@end