iOS simulator OpenGL depth buffer issue

Question

When running my OpenGL1 app on the simulator, very close positioned polygons flicker/merge into one another (the z value isn't right for these pixels). My machine is an old Mac mini.

Seems this only happens in the simulator and everything is fine on the actual device. Does anyone now why? Does the simulator use a depth buffer with a lower bit depth than the iPhone?

Answer 1

The exact precision errors you'll see vary from PowerVR model to model as a lot of it is how internal working values accumulate rather than necessarily the precision at which the final values are stored; I'd guess the simulator is acting correctly within the requirements placed upon it — a buffer of the specified depth, with values calculated as required by the spec — but just happens to make different rounding errors.

The simulator in general isn't an emulator.