Force a retina iPad to use non-retina images

Question

I'm creating an app using OpenGL...

I have a retina iPad, and I'm using a texture that stores @2x images. When my app starts up, the OpenGL framebuffer is created and querying the size of it comes back as 1536x2048 - so far so good.

I also have a texture for non-retina iPad display (768x1024), but I do not have a non-retina iPad. I'd like to force my retina iPad to use the non-retina graphics (i.e, for it to use scale == 1.0). So I'd like it to create a 768x1024 OpenGL framebuffer. The problem is that it always creates a 1536x2048 frame buffer, and scale is always 2.0.

Is there a way of forcing it to use a scale of 1.0, and creating a smaller framebuffer? The base iOS version for the app is 8.0, but since iOS8.0 still works on the iPad2, I'd like to test that resolution as well.

I've tried using UILaunchImages, but that doesn't seem to work? In the past, when an app was written for a non-retina screen, a retina device used to scale the lower resolution to fit the higher-resolution screen, and that's what I want - at least so I can test....

Is UILaunchImages the right way to go to try and get iOS to think that only low-res graphics are available?

Answer 1

IIRC, simply by having an @2x resource (splash, icon, etc..) used to signal iOS that you are running an app with support for Retina. I think since then Apple has added a NSHighResolutionCapable key that you can try to set false in the plist. So try removing all @2x resources from your build and setting that key to false.

Another approach is to change your glViewPort and/or the Projection matrix to scale your logical resolution to 1024x768. I have the opposite problem in that I need to scale non-retina images up to the retina backing scale. I use a Scaling matrix in my stack to fix this.

Ask me how I mix and match retina and non-retina images!