OpenGL, and graphics in general, is a complex and highly technical API. One book is not enough to cover it entirely, but drawing 2D graphics with textures and buffer objects opens the door to much more advanced stuff!

In more detail, you have learned how to initialize an OpenGL ES context and bind it to an Android window. Then, you have seen how to turn libpng into a module and load a texture from a PNG asset. We have used this texture and then combined it with vertex buffers and shaders to render sprites and particles. Finally, we have found a solution to the Android resolution fragmentation issue with a simple off-screen and scaling rendering technique.

OpenGL ES is a complex API that requires an in-depth understanding to get the best performance and quality. This is even true with OpenGL ES 3, which we have not covered here, that is available since Android KitKat. Do not hesitate to have a look at: