Question

我正在尝试创建一个非常简单的关键帧动画，其中图形通过给定的中点从一个角度旋转到另一个角度。

（目的是能够通过 ~~OBTUSE~~ 角度大于180度的弧度来制作旋转动画，而不是让动画'作弊'并走最短的路线，即通过对面~~，ACUTE~~ 更小的角度 - 当只有一个[即目标]关键帧时可能会发生这种情况。为了实现'长'的方式，我认为我需要一个额外的关键帧，沿着期望的弧。）

这是我到目前为止所获得的（通过最锐角将图形转换为所需的旋转）：

#define DEGREES_TO_RADIANS(__ANGLE__) ((__ANGLE__) / 180.0 * M_PI)

...

[UIView beginAnimations:nil context:nil];
CGAffineTransform cgCTM = CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(desiredEndingAngle));
[UIView setAnimationDuration:0.5];
graphic.transform = cgCTM;
[UIView commitAnimations];

据我所知，我不是在寻找沿着Path的动画（因为那是为了翻译而不是旋转）......

无论如何，任何帮助都会非常感激！提前谢谢。

Answer 1

想想我已经明白了。

这里的代码（在本例中）完全旋转270度（1.5 * pi弧度），包括可以进一步定制的各种参数：

CALayer *layer = rotatingImage.layer;
CAKeyframeAnimation *animation;
animation = [CAKeyframeAnimation animationWithKeyPath:@"transform.rotation.z"];
animation.duration = 0.5f;
animation.cumulative = YES;
animation.repeatCount = 1;
animation.values = [NSArray arrayWithObjects:       // i.e., Rotation values for the 3 keyframes, in RADIANS
      [NSNumber numberWithFloat:0.0 * M_PI], 
      [NSNumber numberWithFloat:0.75 * M_PI], 
      [NSNumber numberWithFloat:1.5 * M_PI], nil]; 
animation.keyTimes = [NSArray arrayWithObjects:     // Relative timing values for the 3 keyframes
      [NSNumber numberWithFloat:0], 
      [NSNumber numberWithFloat:.5], 
      [NSNumber numberWithFloat:1.0], nil]; 
animation.timingFunctions = [NSArray arrayWithObjects:
      [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseIn],    // from keyframe 1 to keyframe 2
      [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseOut], nil]; // from keyframe 2 to keyframe 3
animation.removedOnCompletion = NO;
animation.fillMode = kCAFillModeForwards;

[layer addAnimation:animation forKey:nil];

谢谢！

Answer 2

试试这个：

UIImageView* rotatingImage = [[UIImageView alloc] init]];
[rotatingImage setImage:[UIImage imageNamed:@"someImage.png"]];

CATransform3D rotationTransform = CATransform3DMakeRotation(1.0f * M_PI, 0, 0, 1.0);
CABasicAnimation* rotationAnimation = [CABasicAnimation animationWithKeyPath:@"transform"];

rotationAnimation.toValue = [NSValue valueWithCATransform3D:rotationTransform];
rotationAnimation.duration = 0.25f;
rotationAnimation.cumulative = YES;
rotationAnimation.repeatCount = 1;

[rotatingImage.layer addAnimation:rotationAnimation forKey:@"rotationAnimation"];

Answer 3

CGMutablePathRef path = CGPathCreateMutable();
CGPathMoveToPoint(path, NULL, 100, 100);
CGPathAddQuadCurveToPoint(path, NULL, 100, 100, 100, 615);
CGPathAddQuadCurveToPoint(path, NULL, 100, 615, 900, 615);
CGPathAddQuadCurveToPoint(path, NULL, 900, 615, 900, 100);
CGPathAddQuadCurveToPoint(path, NULL, 900, 100, 100, 80);
CAKeyframeAnimation *pathAnimation = [CAKeyframeAnimation animationWithKeyPath:@"position"];
pathAnimation.path = path;
pathAnimation.duration = 10.0;
[someLayer addAnimation:pathAnimation forKey:nil];

基本关键帧动画（旋转）

3 个答案: