@Override
  protected void onDrag(Touch t) {

    camera.target = null;

    if (pinching) {

      float curSpan = PointF.distance(touch.current, another.current);
      camera.zoom(
          GameMath.gate(PixelScene.minZoom, startZoom * curSpan / startSpan, PixelScene.maxZoom));

    } else {

      if (!dragging && PointF.distance(t.current, t.start) > dragThreshold) {

        dragging = true;
        lastPos.set(t.current);

      } else if (dragging) {
        camera.scroll.offset(PointF.diff(lastPos, t.current).invScale(camera.zoom));
        lastPos.set(t.current);
      }
    }
  }