The complete tutorial on how to render a Joystick using OpenGL can be found here:
http://www.haroldserrano.com/blog/how-to-add-a-joystick-to-your-game-using-opengl-es
Rendering a joystick using OpenGL ES 2.0 in iOS
Objective-C++MIT
The complete tutorial on how to render a Joystick using OpenGL can be found here:
http://www.haroldserrano.com/blog/how-to-add-a-joystick-to-your-game-using-opengl-es