Set OpenGL context mode. Modern (3.0+) OpenGL versions deprecated old fixed
pipeline functions, and without "compatible" mode you won't be able to use
your old non-shader-based code with such contexts. By default SimpleDisplay
creates compatible context, so you can gradually upgrade your OpenGL code if
you want to (or leave it as is, as it should "just work").
Set OpenGL context mode. Modern (3.0+) OpenGL versions deprecated old fixed pipeline functions, and without "compatible" mode you won't be able to use your old non-shader-based code with such contexts. By default SimpleDisplay creates compatible context, so you can gradually upgrade your OpenGL code if you want to (or leave it as is, as it should "just work").