iPhone OS 3.0 OpenGL Bug

We ran into a weird OS 3.0 bug. The bug causes the display to become corrupted. As you can see in the screenshot, it's stretched vertically, but mirrored horizontally. The bug only crops up on devices with OS 3.0. And only on the 2nd generation iPod Touch and the new iPhone 3GS.

With the release of the iPhone 3GS Apple now has five devices in the product line. We've been using OS 3.0 since it was released to developers back in March. We've been testing our products against 3.0 since then. What wasn't obvious to us, probably isn't obvious to much of anyone, is that bugs can crop up in only a few of the devices. Just because something works on most of the OS 3.0 devices doesn't mean it works on all of them.

Thankfully the market segment affected by this bug is pretty small. Only 1/30th of all iDevices are iPhone 3GS. And only 30% of iPod Touch users have upgraded to OS 3.0. Google for the references if you're curious.

It took us a while to figure this out. It's an unusual bug. No one in Apple Developer groups seems to have ever seen it. Anyway, it turns out you cannot rotate the OpenGL view on 3.0. It simply doesn't work on all five devices in Apple's lineup. Instead you have to rotate each OpenGL frame as you draw it.

We corrected the problem and there was an update submitted today to the Apple App Store for Abby Craby.