//get screen physical size in pixels
            int w = getWidth();
            int h = getHeight();

//setup OpenGL raster area to whole screen
            gl.glViewport(0, 0, w, h);

//calculate the ratio between screen width and height (formfactor)            
            float ratio = (float)w / h;

//switch to operations with projection matrix
            gl.glMatrixMode(gl.GL_PROJECTION);

//init projection matrix with trivial matrix
            gl.glLoadIdentity();

//setup projection
            gl.glFrustumf(-ratio, ratio, -1, 1, 2, 12);