code: public static void defineMask() {
  		GL.glDepthMask(true);
  		GL.glClearDepth(1);
  		GL.glClear(SGL.GL_DEPTH_BUFFER_BIT);
  		GL.glDepthFunc(SGL.GL_ALWAYS);
  		GL.glEnable(SGL.GL_DEPTH_TEST);
  		GL.glDepthMask(true);
  		GL.glColorMask(false, false, false, false);
  	}
docs: Start defining the screen mask. After calling this use graphics functions to
  mask out the area