3

我正在尝试使用CATransform3DMakeRotation. 我很困惑为什么这个简单的例子没有显示透视图,而是看起来被压扁了。使用时我可以让旋转工作CATransform3DRotate,但我不想旋转,我想旋转到。谢谢。

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];

    UIView *newView = [[UIView alloc] initWithFrame:CGRectMake(100, 100, 100, 100)];
    [newView setBackgroundColor:[UIColor orangeColor]];
    UILabel *newLabel = [[UILabel alloc] initWithFrame:CGRectMake(10, 10, 50, 20)];
    [newLabel setText:@"Hello"];
    [newView addSubview:newLabel];
    [self.window addSubview:newView];

    CALayer *layer = newView.layer;

    CATransform3D perspective = CATransform3DMakeRotation(1.0, 0, 1, 0);
    perspective.m34 = -1 / 500;

    layer.anchorPoint = CGPointMake(1.0, 0.5);
    layer.zPosition = 99;
    layer.transform = perspective;

    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];
    return YES;
}

这是它的截图:

截屏

大卫回答后更新:

只是为了加强大卫关于顺序很重要的观点,我想看看矩阵的差异并将其编码:

CATransform3D transform1 = CATransform3DMakeRotation(-1, 0, 1, 0);
transform1.m34 = -1.0 / 500.0;

NSLog(@"%f %f %f %f", transform1.m11, transform1.m12, transform1.m13, transform1.m14);
NSLog(@"%f %f %f %f", transform1.m21, transform1.m22, transform1.m23, transform1.m24);
NSLog(@"%f %f %f %f", transform1.m31, transform1.m32, transform1.m33, transform1.m34);
NSLog(@"%f %f %f %f", transform1.m41, transform1.m42, transform1.m43, transform1.m44);

NSLog(@"==============================");

CATransform3D transform2 = CATransform3DIdentity;
transform2.m34 = -1.0 / 500.0;
transform2 = CATransform3DRotate(transform2, -1, 0, 1, 0);

NSLog(@"%f %f %f %f", transform2.m11, transform2.m12, transform2.m13, transform2.m14);
NSLog(@"%f %f %f %f", transform2.m21, transform2.m22, transform2.m23, transform2.m24);
NSLog(@"%f %f %f %f", transform2.m31, transform2.m32, transform2.m33, transform2.m34);
NSLog(@"%f %f %f %f", transform2.m41, transform2.m42, transform2.m43, transform2.m44);

NSLog(@"==============================");

CATransform3D transform3 = CATransform3DIdentity;
transform3 = CATransform3DRotate(transform3, -1, 0, 1, 0);
transform3.m34 = -1.0 / 500.0;

NSLog(@"%f %f %f %f", transform3.m11, transform3.m12, transform3.m13, transform3.m14);
NSLog(@"%f %f %f %f", transform3.m21, transform3.m22, transform3.m23, transform3.m24);
NSLog(@"%f %f %f %f", transform3.m31, transform3.m32, transform3.m33, transform3.m34);
NSLog(@"%f %f %f %f", transform3.m41, transform3.m42, transform3.m43, transform3.m44);

产生这个输出:

0.540302 0.000000 0.841471 0.000000
0.000000 1.000000 0.000000 0.000000
-0.841471 0.000000 0.540302 -0.002000
0.000000 0.000000 0.000000 1.000000
==============================
0.540302 0.000000 0.841471 -0.001683
0.000000 1.000000 0.000000 0.000000
-0.841471 0.000000 0.540302 -0.001081
0.000000 0.000000 0.000000 1.000000
==============================
0.540302 0.000000 0.841471 0.000000
0.000000 1.000000 0.000000 0.000000
-0.841471 0.000000 0.540302 -0.002000
0.000000 0.000000 0.000000 1.000000
4

2 回答 2

18

设置该m34值并不能为您提供所有魔法变换的视角(不幸的是)。由于旋转会改变变换的许多不同值,因此您需要在身份消息上设置透视图,然后旋转该变换。

CATransform3D rotationWithPerspective = CATransform3DIdentity;
rotationWithPerspective.m34 = -1.0/500.0;
rotationWithPerspective = CATransform3DRotate(rotationWithPerspective, angle, 0, 1, 0);

这里与您所做的不同之处在于您创建了一个单位矩阵并对其进行透视,然后旋转该矩阵。问题是顺序很重要。


如果您了解矩阵数学,那么您可以验证两种转换之间的差异,并了解为什么您的转换没​​有给您任何视角。如果您有兴趣了解转换背后的数学,我写了一篇关于此的博客文章(警告:它很长并且只包含数学)。

于 2013-02-12T21:29:21.090 回答
0

我一直觉得 m34 属性很挑剔,试试这个:

CATransform3D transform = CATransform3DIdentity;

代替CATransform3DMakeRotation(1.0, 0, 1, 0);

于 2013-02-12T20:18:35.323 回答