This is an interactive (!) tutorial, where you can learn about technology used by many games. Why interactive? Because apart from reading about OpenGL ES, you can also change parameters and these changes immediately are reflected in OpenGL ES demonstrations (that run inside of this app) and in code snippets (that you can copy and paste to other apps). OpenGL ES is a mobile version of OpenGL - a software interface to graphics hardware and it is easy to learn but difficult to master. You don't have to be programmer to find this app interesting, as you can learn about this popular technology and you can play with OpenGL drawing without the need to code. No Internet connection is required or needed to use this app. If you want to see some specific geometric primitives added to this app, please send us tweet to @celltica !