@Override
  protected void doRender(DrawContext dc) {
    if (this.frameTimestamp != dc.getFrameTimeStamp()) {
      this.assembleControlPoints(dc);
      this.frameTimestamp = dc.getFrameTimeStamp();
    }

    this.markerRenderer.render(dc, this.controlPoints);

    if (this.annotation != null && isShowAnnotation()) {
      this.annotation.render(dc);
    }
  }
  protected void assembleControlPoints(DrawContext dc) {
    // Control points are re-computed each frame
    this.controlPoints = new ArrayList<Marker>();

    this.assembleVertexControlPoints(dc);
    if (!dc.is2DGlobe()) this.assembleHeightControlPoints();
  }
  protected void assembleVertexControlPoints(DrawContext dc) {
    Terrain terrain = dc.getTerrain();
    ExtrudedPolygon polygon = this.getPolygon();

    Position refPos = polygon.getReferencePosition();
    Vec4 refPoint = terrain.getSurfacePoint(refPos.getLatitude(), refPos.getLongitude(), 0);

    int altitudeMode = polygon.getAltitudeMode();
    double height = polygon.getHeight();

    Vec4 vaa = null;
    double vaaLength = 0; // used to compute independent length of each cap vertex
    double vaLength = 0;

    int i = 0;
    for (LatLon location : polygon.getOuterBoundary()) {
      Vec4 vert;

      // Compute the top/cap point.
      if (altitudeMode == WorldWind.CONSTANT || !(location instanceof Position)) {
        if (vaa == null) {
          // Compute the vector lengths of the top and bottom points at the reference position.
          vaa = refPoint.multiply3(height / refPoint.getLength3());
          vaaLength = vaa.getLength3();
          vaLength = refPoint.getLength3();
        }

        // Compute the bottom point, which is on the terrain.
        vert = terrain.getSurfacePoint(location.getLatitude(), location.getLongitude(), 0);

        double delta = vaLength - vert.dot3(refPoint) / vaLength;
        vert = vert.add3(vaa.multiply3(1d + delta / vaaLength));
      } else if (altitudeMode == WorldWind.RELATIVE_TO_GROUND) {
        vert =
            terrain.getSurfacePoint(
                location.getLatitude(),
                location.getLongitude(),
                ((Position) location).getAltitude());
      } else // WorldWind.ABSOLUTE
      {
        vert =
            terrain
                .getGlobe()
                .computePointFromPosition(
                    location.getLatitude(),
                    location.getLongitude(),
                    ((Position) location).getAltitude() * terrain.getVerticalExaggeration());
      }

      Position vertexPosition = this.wwd.getModel().getGlobe().computePositionFromPoint(vert);

      this.controlPoints.add(
          new ControlPointMarker(
              MOVE_VERTEX_ACTION, vertexPosition, vert, this.vertexControlAttributes, i));
      i++;
    }
  }
    @Override
    public void render(DrawContext dc) {
      if (dc.isPickingMode() && this.isResizeable()) return;

      // This is called twice: once during normal rendering, then again during ordered surface
      // rendering. During
      // normal renering we render both the interior and border shapes. During ordered surface
      // rendering, both
      // shapes are already added to the DrawContext and both will be individually processed.
      // Therefore we just
      // call our superclass behavior
      if (dc.isOrderedRenderingMode()) {
        super.render(dc);
        return;
      }

      if (!this.isResizeable()) {
        if (this.hasSelection()) {
          this.doRender(dc);
        }
        return;
      }

      PickedObjectList pos = dc.getPickedObjects();
      PickedObject terrainObject = pos != null ? pos.getTerrainObject() : null;

      if (terrainObject == null) return;

      if (this.getStartPosition() != null) {
        Position end = terrainObject.getPosition();
        if (!this.getStartPosition().equals(end)) {
          this.setEndPosition(end);
          this.setSector(Sector.boundingSector(this.getStartPosition(), this.getEndPosition()));
          this.doRender(dc);
        }
      } else {
        this.setStartPosition(pos.getTerrainObject().getPosition());
      }
    }
    public void preRender(DrawContext dc) {
      // This is called twice: once during normal rendering, then again during ordered surface
      // rendering. During
      // normal renering we pre-render both the interior and border shapes. During ordered surface
      // rendering, both
      // shapes are already added to the DrawContext and both will be individually processed.
      // Therefore we just
      // call our superclass behavior
      if (dc.isOrderedRenderingMode()) {
        super.preRender(dc);
        return;
      }

      this.doPreRender(dc);
    }