三角がみえてくる錯視 「カニッツァの三角形」を表示するiPhoneアプリのサンプルコードを描いてみます。
#import “ViewController.h”
@interface ViewController ()
@end
@implementation ViewController
– (void)viewDidLoad
{
[super viewDidLoad];
}
– (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
CGPoint p = [[touches anyObject] locationInView:self.view];
UIView *v = [[UIView alloc] initWithFrame:self.view.frame];
v.backgroundColor = [UIColor clearColor];
v.userInteractionEnabled = NO;
[self.view addSubview:v];
float dAngle = 2.0 * M_PI / 3.0;
for (int i=0; i<3; i++) {
float x = 60 * cos(dAngle * i) + p.x;
float y = 60 * sin(dAngle * i) + p.y;
CALayer *l = [self createCircle:20];
l.position = CGPointMake(x, y);
l.transform = CATransform3DMakeRotation(dAngle * i – 5.0*M_PI/6.0, 0, 0, 1);
[v.layer addSublayer:l];
CATransform3D t = CATransform3DMakeTranslation(-x + p.x, -y + p.y, 0);
t = CATransform3DRotate(t, dAngle * i – 5.0*M_PI/6.0, 0, 0, 1);
CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@”transform”];
animation.duration = 3;
animation.fromValue = [NSValue valueWithCATransform3D:t];
animation.toValue = [NSValue valueWithCATransform3D:CATransform3DMakeRotation(dAngle * i – 5.0*M_PI/6.0, 0, 0, 1)];
[l addAnimation:animation forKey:nil];
}
v.layer.anchorPoint = CGPointMake(p.x/CGRectGetMaxX(v.frame), p.y/CGRectGetMaxY(v.frame));
v.layer.position = p;
[UIView animateWithDuration:2.0 animations:^{
v.transform = CGAffineTransformMakeRotation(M_PI * 1.5);
}];
}
– (CAShapeLayer *)createCircle:(float)r
{
UIBezierPath *path = [UIBezierPath bezierPath];
[path addArcWithCenter:CGPointZero radius:r startAngle:0 endAngle:(5.0/3.0) * M_PI clockwise:YES];
[path addLineToPoint:CGPointZero];
[path closePath];
CAShapeLayer *circle = [CAShapeLayer layer];
circle.path = path.CGPath;
float hue = arc4random() % 10;
circle.fillColor = [UIColor colorWithHue:hue * 0.1 saturation:0.8 brightness:1.0 alpha:0.7].CGColor;
return circle;
}
– (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
@end