GLKViewController orientation animation - ios

Question

I have a layout, where the screen is divided into 2 parts: UIView at the top and GLKViewController at the bottom. The problem is that when the screen orientation changes the
GLKViewController part is rotated and gradually stretched out until the animation finishes, at which point a new unstretched frame will be drawn.
Is there a way to disable the automatic rotation animation for the GLKViewController, so I could animate it manually by manipulating the modelview-projection matrix?

Answer 1

If you're just looking to deal with the stretching effect, you don't need to replace the whole orientation/rotation system. Depending on how much you're making use of device orientation in you're app's UI, you're likely to cause yourself more maintenance headaches by reimplementing orientation and rotation. (If you need to do more than just work around the stretching effect, the other answers are still good.)
Your view is drawing itself during the rotation animation, so all you need to do is ensure that it's drawing itself in a way that matches its intermediate size during the animation. The rotation animation is handled by Core Animation, so you use its presentationLayer method to access the transitory state during the animation. For example:
CALayer *presentationLayer = [self.view.layer presentationLayer];
CGSize layerSize = presentationLayer.bounds.size;
float aspect = fabsf(layerSize.width / layerSize.height);
GLKMatrix4 projectionMatrix = GLKMatrix4MakePerspective(
GLKMathDegreesToRadians(65.0f), aspect, 0.1f, 100.0f);
Run this snippet as part of your update/draw loop — note this might mean moving calculation of your projection matrix into the update/draw loop if it isn't there already. (You might also want to make sure this snippet only runs every frame if an orientation change is in progress.)
To see the animation in progress and make sure it's working right, use the "Toggle Slow Animations" command in the iOS Simulator.
(Credit where due: code is from this answer.)

Answer 2

GLKViewController is a subclass of UIViewController. UIViewController has a method willAnimateRotationToInterfaceOrientation:duration: You can override it and configure the animation of view.
You can find more details in the documentation: UIViewController Class Reference under the Responding to View Rotation Events section.

Answer 3

Depending on what you want to achieve, you would do different things to disable automatic rotation.
If you do not need rotation at all, disable it at project level. In Xcode, use the navigator to select the project (top item of the file list) and visit the "General" section of the target app. For device orientations, untick everything but "Portrait":
If you need to disable it for some "screens" and not for others, you need to disable rotation at the UIViewController level. UIViewController was initially designed to take up the whole screen area, so if you are using a GLKViewController that manages GLKView that covers the screen just partially, it is most probably inside another view controller. You need to subclass the parent view controller and add these methods:
// From iOS 6
- (BOOL)shouldAutorotate
{
return NO;
}
- (NSUInteger)supportedInterfaceOrientations
{
return UIInterfaceOrientationMaskPortrait;
}
// iOS 5
- (BOOL)shouldRotateToOrientation:(UIInterfaceOrientation)orientation
{
return NO;
}
These will prevent the parent view controller from being rotated.
Finally, if you need to allow rotation of some elements on the screen, but not others, then you will have to determine which method to use:
Allow the screen to rotate while rotating back those elements you want to remain static. I would not recommend it.
Block the screen from rotating as mentioned above, and manually rotating those elements that you want rotated by setting their transform property. This is what I would go for.