bounces animation

- (void)animateFromPoint:(CGPoint)startPoint toPoint:(CGPoint)endPoint duration:(CGFloat)duration {
    NSLog(@"------%s-------",__func__);
    CGFloat r = sqrtf(powf(startPoint.x - endPoint.x, 2) + powf(startPoint.y - endPoint.y, 2));
    
    NSLog(@"r = %f",r);
    
    CGFloat SIN = (startPoint.y - endPoint.y) / r;
    CGFloat COS = (startPoint.x - endPoint.x) / r;
    
    NSLog(@"-----------------");
    NSLog(@"SIN = %f", SIN);
    NSLog(@"COS = %f", COS);
    
    CGFloat farRedius = r + 50;
    CGFloat nearRedius = r - 30;
    
    NSLog(@"------------------");
    NSLog(@"farRedius = %f",farRedius);
    NSLog(@"nearRedius = %f", nearRedius);
    
    CGPoint farPoint = CGPointMake(startPoint.x - COS * farRedius, startPoint.y - SIN * farRedius);
    CGPoint nearPoint = CGPointMake(startPoint.x - COS * nearRedius, startPoint.y - SIN * nearRedius);
    
    CGMutablePathRef path = CGPathCreateMutable();
    CGPathMoveToPoint(path, NULL, startPoint.x, startPoint.y);
    CGPathAddLineToPoint(path, NULL, farPoint.x, farPoint.y);
    CGPathAddLineToPoint(path, NULL, nearPoint.x, nearPoint.y);
    CGPathAddLineToPoint(path, NULL, endPoint.x, endPoint.y);
    
    CAKeyframeAnimation *animation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
    animation.path = path;
    animation.duration = duration;
    animation.delegate = self;
    
    
    CGPathRelease(path);
}