How is CATransform3DMakeRotation used?

Question

I can not figure out how to use CATransform3DMakeRotation(). Can somebody please tell me how to use it?

I think the first parameter is the angle, right? But what are the other three?

Solution 1

The first is the angle in radians the other 3 parameters are the axis (x, y, z). So for example if you want to rotate 180 degrees around the z axis just call the function like this:

myView.layer.transform = CATransform3DMakeRotation(M_PI, 0.0, 0.0, 1.0);

and apply the result to the transform property of the view you want to rotate.

Solution 2

You'll probably find these useful when using radians:

CGFloat DegreesToRadians(CGFloat degrees)
{
  return degrees * M_PI / 180;
};

CGFloat RadiansToDegrees(CGFloat radians)
{
  return radians * 180 / M_PI;
};

Solution 3

They represent the axis about which you want to rotate. Use 0,0,1 to rotate in the plane of the screen.

Comments

[Brad Larson]

See also the Core Animation Function Reference for the definition of the function: developer.apple.com/documentation/quartzcore/…

[Daniel says Reinstate Monica]

so basically i just set the angle and put 1.0 on the x, y, or, z that i want to use? is it always 1.0?

[Brad Larson]

@Dan - No, it's not always 1.0 for the axes. The X, Y, and Z components define an axis about which rotation takes place. Setting 1.0 for a component, and leaving the other to at 0.0, defines a rotation about the X, Y, or Z axis, but you can rotate about any arbitrary direction. This lets you manipulate views and layers in a truly 3-D manner.