Question

I’m creating an OpenGL-based 2D game. I want to create a loading screen to load my assets. I want to draw something to show the user that something is loading. But I learned that I can’t use a separate thread like asynctask to load my textures. So I’m stuck there. How can I create a loading screen to load my assets?

Answer 1

Depends what you mean by “load”. The loading is a two-step process:

1. Load the image into (main) memory. This can be done from any thread.
2. Create the texture by loading the image into video memory. This has to be done from the GL thread.

The texture creation a la glTexImage2d can slow things down a bit temporarily in terms of FPS, but this isn’t a problem normally, especially when you’re showing a (static) loading screen.

So in principle you could do all of the loading on the GL thread, if your splash screen is static (i.e. nothing moves and hence FPS doesn’t matter):

1. Load the splash screen assets into memory
2. Create the splash screen texture & draw splash screen
3. Load the game assets into memory
4. Create the game screen textures & draw game screen

If your splash screen is dynamic however, you will want to do 3. on a separate loading thread, and once that is done, create the game textures on the GL thread. This requires signalling from the loading thread to the GL thread that the loading of the assets is ready for texture creation.