static_cast<SphereDragger*>(_llDragger)->setColor(osg::Vec4(0,0,1,0));

Alpha寫成了0

應該寫成

static_cast<SphereDragger*>(_llDragger)->setColor(osg::Vec4(0,0,1,1));

osgEarth::Annotation::RectangleNodeEditor* rectEditor = new osgEarth::Annotation::RectangleNodeEditor(rect);
rectEditor->_llDragger->setColor(osg::Vec4(1, 0, 0, 1));
rectEditor->getPositionDragger()->setColor(osg::Vec4(0, 1, 0, 1));

osgearth2.8關於RectangleNodeEditor編輯點不可見的問題