Retina how-to (iPhone 4 resolution)

This is a guide on how to get Retina display support working with iTorque. All of this has been done in my game (in review at the moment) and it works well :)

Huge thanks goes to Scott Wilson for helping me with this and also for Dean Parkers resources.

It should be noted that in addition to all the following code I made my game universal with Dean Parker's resource.

*** 1. First we need to implement detection of iPhone 4. We definitely don't want to detect iPhone4 specifically. Instead a code detects if the resolution is scaled up and that code might come handy in the future for other devices.

In iPhoneWindow.mm in function Platform::initWindow() we have to fix our main window size to fit with the shiny high-resolution of iPhone4. Add the following just before gScreenOrientation = Con::getIntVariable( "$pref::iDevice::ScreenOrientation" );

if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)] && [[UIScreen mainScreen] scale] == 2) {
	platState.windowSize.x = 960;
	platState.windowSize.y = 640;
}

Just after glView = [[iPhoneOGLVideo alloc] initWithFrame: rect] add the following:

if (UI_USER_INTERFACE_IDIOM() == UIUserInterfaceIdiomPad) { 
	Con::setVariable( "$platform", "ipad" );    
} else {   
        if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)] && [[UIScreen mainScreen] scale] == 2) {
	        Con::setVariable( "$platform", "iphone4" );
	        glView.contentScaleFactor = [[UIScreen mainScreen] scale];		
	}  else {  
	        Con::setVariable( "$platform", "iphone" );  
}

That will set values to the variable $platform and it will be used to determine what resources to load later on.

*** 2. My game was locked to portrait mode so I had to do some adjustments to the render view as the render window was in wrong place (edit this if you find any problems with this)

In bool::setScreenOrientation() inside if( platState.portrait )
{ brackets replace:

glPositionPoint.x = point.x;
glPositionPoint.y = point.y;

with:

if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)] && [[UIScreen mainScreen] scale] == 2) {
	glPositionPoint.x = 480;
	glPositionPoint.y = 160;
} 
else 
{
	glPositionPoint.x = point.x;
	glPositionPoint.y = point.y;
}

*** 3. I had to to change the some values in the touch events in iPhoneOGLVideo.mm to make it the touches work in portrait mode.
I'm not sure how it works in landscape so try first before implement code. If you find issues however you need to correct calculation to make it work in the following functions...

The functions that needs to be edited is (void)touchesEnded, (void)touchesBegan, (void)touchesMoved.

In all these functions do a check for upscaled resolution:

NSUInteger touchCount = 0; // Leave this as it is

if ([[UIScreen mainScreen] respondsToSelector:@selector(scale)] && [[UIScreen mainScreen] scale] == 2 && platState.portrait) {       
        // Add the existing code in the function here but you need to add before the code
        // Need to fix coordinates if Retina display!
	point.x *= 2;
	point.y = ((point.y - 400) * 2) + 480;
}
else {
    // Add the existing code in the function here as it was
}

*** 3. Change the camera size in your levels to fit the resolution, 640x960 if portrait and 960x640 if landscape.

*** 4. Change your GUI's to fit the new resolution. You can use Dean Parker's great script here for that.

*** 5. Use variables to determine what resources to load. For example in main.cs I check what platform and load specific levels and resources for all the platforms based on the variable $platform.

A note should be added that I had a drop of whopping 20fps on iPhone4 device when using this code. I'm not actually sure why as the code was tried first with hardly anything in the scene. It might be related to the detection of scaling in the touch events but I left as it was as it was working ;)

If you're making your game universal try to use your iPad images for iPhone4 as this will make your app smaller.