iphone动画：为什么围绕X轴旋转UILabel会切断它的下半部分？ [英] iphone Animation: why does rotating a UILabel around X axis cut off its bottom half?

问题描述

我想围绕X轴旋转UILabel，并为其设置动画。但是当动画开始时，标签的文本会在水平方向上切成两半。下半部分消失，上半部分旋转。为什么？

I want to rotate a UILabel around the X axis, and animating it. But when the animation starts, the text of the label is cut in two, horizontally. The bottom half disappears, the upper half is rotating. Why?

这是代码：

CATransform3D _3Dt = CATransform3DMakeRotation(radians(90.0f), 1.0, 0.0, 0.0);

CABasicAnimation *transformAnimation = [CABasicAnimation animationWithKeyPath:@"transform"];

transformAnimation.removedOnCompletion = NO;

transformAnimation.toValue = [NSValue valueWithCATransform3D:_3Dt];

transformAnimation.fillMode = kCAFillModeForwards;

（sdk 3.0）

推荐答案

X轴？这意味着在旋转期间，UILabel的一半将具有 z> 0 （在屏幕前），一半将 z< 0 （在屏幕后面）。

X axis? That means during the rotation half of the UILabel will have z > 0 (in front of the screen) and half will have z < 0 (behind the screen).

如果在 z == 0 他们将覆盖你的UILabel的 z< 0 一半。

If there's other layers at z == 0 they will cover your UILabel's z < 0 half.

尝试增加标签的图层 zPosition 。

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