从CATransform3D到CGAffineTransform [英] From CATransform3D to CGAffineTransform

问题描述

我正在使用以下功能将脉冲效果应用于视图

I'm using the following function to apply a pulse effect to a view

- (void)pulse {

    CATransform3D trasform = CATransform3DScale(self.layer.transform, 1.15, 1.15, 1);
    trasform = CATransform3DRotate(trasform, angle, 0, 0, 0);

    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"transform"];
    animation.toValue = [NSValue valueWithCATransform3D:trasform];
    animation.autoreverses = YES;
    animation.duration = 0.3;
    animation.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
    animation.repeatCount = 2;
    [self.layer addAnimation:animation forKey:@"pulseAnimation"];

}

我想使用以下方法获得相同的结果

推荐答案

这可能吗？将 CATransform3D 转换为 CGAffineTransform ，但是您将失去一些功能。我发现将图层及其祖先的聚合变换转换为 CGAffineTransform 很有用，因此可以使用Core Graphics进行渲染。约束是：

It's possible convert a CATransform3D to a CGAffineTransform, but you will lose some capabilities. I found it useful to convert the aggregate transform of a layer and its ancestors into a CGAffineTransform so I could render it with Core Graphics. The constraints are:

• 您的输入将在XY平面上视为平坦


• 您的输出也会在XY平面上视为平坦的。


• 从 .m34 的透视/透视将被抵消

• Your input will be treated as flat in the XY plane
• Your output will be treated as flat in the XY plane too
• Perspective / foreshortening from .m34 will be neutralized

如果这对您有帮助：

    // m13, m23, m33, m43 are not important since the destination is a flat XY plane.
    // m31, m32 are not important since they would multiply with z = 0.
    // m34 is zeroed here, so that neutralizes foreshortening. We can't avoid that.
    // m44 is implicitly 1 as CGAffineTransform's m33.
    CATransform3D fullTransform = <your 3D transform>
    CGAffineTransform affine = CGAffineTransformMake(fullTransform.m11, fullTransform.m12, fullTransform.m21, fullTransform.m22, fullTransform.m41, fullTransform.m42);

您首先要在3D变换中完成所有工作，例如从上层连接起来，然后然后将汇总的 CATransform3D 转换为 CGAffineTransform 。鉴于图层开始是平坦的并渲染到平坦的目标上，所以我发现这非常合适，因为我的3D旋转变成了2D剪切。我还发现牺牲透视图是可以接受的。之所以无法解决，是因为仿射变换必须保留平行线。

You will want to do all your work in 3D transforms first, say by concatenating from your superlayers, and then finally convert the aggregate CATransform3D to a CGAffineTransform. Given that layers are flat to begin with and render onto a flat target, I found this very suitable since my 3D rotations became 2D shears. I also found it acceptable to sacrifice foreshortening. There's no way around that because affine transforms have to preserve parallel lines.

例如，要使用Core Graphics渲染3D变换的图层，您可以将变换连接起来（尊重锚点！），然后转换为仿射，最后：

To render a 3D-transformed layer using Core Graphics, for instance, you might concatenate the transforms (respecting anchor points!), then convert to affine, and finally:

    CGContextSaveGState(context);
    CGContextConcatCTM(context, affine);
    [layer renderInContext:context];
    CGContextRestoreGState(context);

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