code: public boolean startClipped (int x, int y, int width, int height) {
      batch.flush(); // flush any pending unclipped calls
      Rectangle r = pushScissorState(x, target.flip() ? target.height()-y-height : y, width, height);
      batch.gl.glScissor(r.x, r.y, r.width, r.height);
      if (scissorDepth == 1) batch.gl.glEnable(GL20.GL_SCISSOR_TEST);
      batch.gl.checkError("startClipped");
      return !r.isEmpty();
    }
docs: Starts a series of drawing commands that are clipped to the specified rectangle (in view
  coordinates, not OpenGL coordinates). Thus must be followed by a call to {@link #endClipped}
  when the clipped drawing commands are done.
  
  @return whether the resulting clip rectangle is non-empty. <em>Note:</em> the caller may wish
  to skip their drawing if this returns false, but they must still call {@link #endClipped}.