Draw text in OpenGL ES (Android)

Question

Hi!

I'm currently developing a small OpenGL game for the Android platform and I wonder if there's an easy way to render text on top of the rendered frame (like a HUD with the player´s score etc). The text would need to use a custom font also. I've seen an example using a View as an overlay, but I don't know if I want to do that since I might want to port the game to other platforms later. Any ideas?

Regards/Per

Answer 1

If you insist on using GL, you could render the text on to textures. Assuming that most of the HUD is relatively static, you shouldn't have to load the textures to texture memory too often.

Answer 2

Look at the "Sprite Text" sample in the GLSurfaceView samples.

Answer 3

I looked at the sprite text example and it looks awfully complicated for such a task, I considered rendering to a texture too, but I'm worried about the performance hit that might cause. I might just have to go with a view instead and worry about porting when it's time to cross that bridge :)

Answer 4

The Android SDK doesn't come with any easy way to draw text on OpenGL views. Leaving you with the following options.

1. Place a TextView over your SurfaceView. This is slow and bad, but the most direct approach.
2. Render common strings to textures, and simply draw those textures. This is by far the simplest and fastest, but the least flexible.
3. Roll-your-own text rendering code based on a sprite. Probably second best choice if 2 isn't an option. A good way to get your feet wet but note that while it seems simple (and basic features are), it get's harder and more challenging as you add more features (texture-alignment, dealing with line-breaks, variable-width fonts etc.) - if you take this route, make it as simple as you can get away with!
4. Use an off-the-shelf/open-source library. There are a few around if you hunt on Google, the tricky bit is getting them integrated and running. But at least, once you do that, you'll have all the flexibility and maturity they provide.