I’ve been learning OpenGL ES 2.0/GLSL and related iOS quirks by looking at code and developer videos and I’ve noticed that there’s never any mention of asynchronous shader compilation. Aside from instructors, writers, or salesmen (er, engineers) worrying about adding complexity to their examples, is there a reason for that?
For example, most web data retrieval tutorials hammer home the need for doing some sort of gymnastics (pthreads, NSOperation, GCD, baked in asynch instance methods, etc) to keep from blocking the main thread- why would blocking an app launch be considered acceptable?
It can be a little bit tricky to synchronize two
EAGLContext‘s, beside that, there is nothing against loading this kind of stuff in the background (generally, loading every kind of asset, textures, shaders etc).Probably the real reasons are that most people think of OpenGL (ES) as something monolithic that only works on one single thread or they never had an issue with loading times that made it worth to load stuff in a background thread or they just don’t care (for some people its probably everything together).
For your last question: Networking can add a HUGE latence and with “can” I mean “will”. Resource loading isn’t that problematic, compared to a network access, loading a shader or texture takes way less time and its already known ahead how much time it will take in the normal case. Plus, people are used to loading screens in game while they don’t want to see loading screens when they scroll a table view just so that your application can fetch a picture from a server that doesn’t respond.