@Override
    public void glViewport(int x, int y, int width, int height) {
        JmeIosGLES.glViewport(x, y, width, height);
    }
Implements OpenGL ES 2.0 and 3.0 for iOS. 

@author Kirill Vainer, Jesus Oliver
jme3-ios/src/main/java/com/jme3/renderer/ios/IosGL.java