/**
     * Performs one line of sight calculation between the reference position and a specified grid
     * position.
     *
     * @param gridPosition the grid position.
     * @throws InterruptedException if the operation is interrupted.
     */
    protected void performIntersection(Position gridPosition) throws InterruptedException {
      // Intersect the line between this grid point and the selected position.
      Intersection[] intersections = this.terrain.intersect(this.referencePosition, gridPosition);
      if (intersections == null || intersections.length == 0) {
        // No intersection, so the line goes from the center to the grid point.
        this.sightLines.add(new Position[] {this.referencePosition, gridPosition});
        return;
      }

      // Only the first intersection is shown.
      Vec4 iPoint = intersections[0].getIntersectionPoint();
      Vec4 gPoint =
          terrain.getSurfacePoint(
              gridPosition.getLatitude(), gridPosition.getLongitude(), gridPosition.getAltitude());

      // Check to see whether the intersection is beyond the grid point.
      if (iPoint.distanceTo3(this.referencePoint) >= gPoint.distanceTo3(this.referencePoint)) {
        // Intersection is beyond the grid point; the line goes from the center to the grid point.
        this.addSightLine(this.referencePosition, gridPosition);
        return;
      }

      // Compute the position corresponding to the intersection.
      Position iPosition = this.terrain.getGlobe().computePositionFromPoint(iPoint);

      // The sight line goes from the user-selected position to the intersection position.
      this.addSightLine(this.referencePosition, new Position(iPosition, 0));

      // Keep track of the intersection positions.
      this.addIntersectionPosition(iPosition);

      this.updateProgress();
    }
  protected void assembleHeightControlPoints() {
    if (this.controlPoints.size() < 2) return;

    // Add one control point for the height between the first and second vertices.
    // TODO: ensure that this control point is visible
    Position firstVertex = this.controlPoints.get(0).getPosition();
    Position secondVertex = this.controlPoints.get(1).getPosition();

    Globe globe = this.wwd.getModel().getGlobe();

    // Get cartesian points for the vertices
    Vec4 firstPoint = globe.computePointFromPosition(firstVertex);
    Vec4 secondPoint = globe.computePointFromPosition(secondVertex);

    // Find the midpoint of the line segment that connects the vertices
    Vec4 halfwayPoint = firstPoint.add3(secondPoint).divide3(2.0);

    Position halfwayPosition = globe.computePositionFromPoint(halfwayPoint);

    this.controlPoints.add(
        new ControlPointMarker(
            CHANGE_HEIGHT_ACTION,
            halfwayPosition,
            halfwayPoint,
            this.heightControlAttributes,
            this.controlPoints.size()));
  }
  protected void requestTile(DrawContext dc, Tile tile) {
    Vec4 centroid = dc.getGlobe().computePointFromPosition(tile.getSector().getCentroid(), 0);
    if (this.getReferencePoint() != null)
      tile.setPriority(centroid.distanceTo3(this.getReferencePoint()));

    RequestTask task = new RequestTask(tile, this);
    this.getRequestQ().add(task);
  }
  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++;
    }
  }
  protected static boolean isNameVisible(
      DrawContext dc, PlaceNameService service, Position namePosition) {
    double elevation = dc.getVerticalExaggeration() * namePosition.getElevation();
    Vec4 namePoint =
        dc.getGlobe()
            .computePointFromPosition(
                namePosition.getLatitude(), namePosition.getLongitude(), elevation);
    Vec4 eyeVec = dc.getView().getEyePoint();

    double dist = eyeVec.distanceTo3(namePoint);
    return dist >= service.getMinDisplayDistance() && dist <= service.getMaxDisplayDistance();
  }
Esempio n. 6
0
  // Draw the scale label
  private void drawLabel(DrawContext dc, String text, Vec4 screenPoint) {
    TextRenderer textRenderer =
        OGLTextRenderer.getOrCreateTextRenderer(dc.getTextRendererCache(), this.defaultFont);

    Rectangle2D nameBound = textRenderer.getBounds(text);
    int x = (int) (screenPoint.x() - nameBound.getWidth() / 2d);
    int y = (int) screenPoint.y();

    textRenderer.begin3DRendering();

    textRenderer.setColor(this.getBackgroundColor(this.color));
    textRenderer.draw(text, x + 1, y - 1);
    textRenderer.setColor(this.color);
    textRenderer.draw(text, x, y);

    textRenderer.end3DRendering();
  }
  /**
   * Add a vertex to the polygon's outer boundary.
   *
   * @param mousePoint the point at which the mouse was clicked. The new vertex will be placed as
   *     near as possible to this point, at the elevation of the polygon.
   */
  protected void addVertex(Point mousePoint) {
    // Try to find the edge that is closest to a ray passing through the screen point. We're trying
    // to determine
    // the user's intent as to which edge a new two control points should be added to.

    Line ray = this.wwd.getView().computeRayFromScreenPoint(mousePoint.getX(), mousePoint.getY());
    Vec4 pickPoint = this.intersectPolygonAltitudeAt(ray);

    double nearestDistance = Double.MAX_VALUE;
    int newVertexIndex = 0;

    // Loop through the control points and determine which edge is closest to the pick point
    for (int i = 0; i < this.controlPoints.size(); i++) {
      ControlPointMarker thisMarker = (ControlPointMarker) this.controlPoints.get(i);
      ControlPointMarker nextMarker =
          (ControlPointMarker) this.controlPoints.get((i + 1) % this.controlPoints.size());

      Vec4 pointOnEdge =
          AirspaceEditorUtil.nearestPointOnSegment(thisMarker.point, nextMarker.point, pickPoint);
      if (!AirspaceEditorUtil.isPointBehindLineOrigin(ray, pointOnEdge)) {
        double d = pointOnEdge.distanceTo3(pickPoint);
        if (d < nearestDistance) {
          newVertexIndex = i + 1;
          nearestDistance = d;
        }
      }
    }

    Position newPosition = this.wwd.getModel().getGlobe().computePositionFromPoint(pickPoint);

    // Copy the outer boundary list
    ArrayList<Position> positionList = new ArrayList<Position>(this.controlPoints.size());
    for (LatLon position : this.getPolygon().getOuterBoundary()) {
      positionList.add((Position) position);
    }

    // Add the new vertex
    positionList.add(newVertexIndex, newPosition);

    this.getPolygon().setOuterBoundary(positionList);
  }
Esempio n. 8
0
 /**
  * Computes the lat/lon of the pickPoint over the world map
  *
  * @param dc the current <code>DrawContext</code>
  * @param locationSW the screen location of the bottom left corner of the map
  * @param mapSize the world map screen dimension in pixels
  * @return the picked Position
  */
 protected Position computePickPosition(DrawContext dc, Vec4 locationSW, Dimension mapSize) {
   Position pickPosition = null;
   Point pickPoint = dc.getPickPoint();
   if (pickPoint != null) {
     Rectangle viewport = dc.getView().getViewport();
     // Check if pickpoint is inside the map
     if (pickPoint.getX() >= locationSW.getX()
         && pickPoint.getX() < locationSW.getX() + mapSize.width
         && viewport.height - pickPoint.getY() >= locationSW.getY()
         && viewport.height - pickPoint.getY() < locationSW.getY() + mapSize.height) {
       double lon = (pickPoint.getX() - locationSW.getX()) / mapSize.width * 360 - 180;
       double lat =
           (viewport.height - pickPoint.getY() - locationSW.getY()) / mapSize.height * 180 - 90;
       double pickAltitude = 1000e3;
       pickPosition = new Position(Angle.fromDegrees(lat), Angle.fromDegrees(lon), pickAltitude);
     }
   }
   return pickPosition;
 }
  /**
   * Compute points on either side of a line segment. This method requires a point on the line, and
   * either a next point, previous point, or both.
   *
   * @param point Center point about which to compute side points.
   * @param prev Previous point on the line. May be null if {@code next} is non-null.
   * @param next Next point on the line. May be null if {@code prev} is non-null.
   * @param leftPositions Left position will be added to this list.
   * @param rightPositions Right position will be added to this list.
   * @param halfWidth Distance from the center line to the left or right lines.
   * @param globe Current globe.
   */
  protected void generateParallelPoints(
      Vec4 point,
      Vec4 prev,
      Vec4 next,
      List<Position> leftPositions,
      List<Position> rightPositions,
      double halfWidth,
      Globe globe) {
    if ((point == null) || (prev == null && next == null)) {
      String message = Logging.getMessage("nullValue.PointIsNull");
      Logging.logger().severe(message);
      throw new IllegalArgumentException(message);
    }
    if (leftPositions == null || rightPositions == null) {
      String message = Logging.getMessage("nullValue.PositionListIsNull");
      Logging.logger().severe(message);
      throw new IllegalArgumentException(message);
    }
    if (globe == null) {
      String message = Logging.getMessage("nullValue.GlobeIsNull");
      Logging.logger().severe(message);
      throw new IllegalArgumentException(message);
    }

    Vec4 offset;
    Vec4 normal = globe.computeSurfaceNormalAtPoint(point);

    // Compute vector in the direction backward along the line.
    Vec4 backward = (prev != null) ? prev.subtract3(point) : point.subtract3(next);

    // Compute a vector perpendicular to segment BC, and the globe normal vector.
    Vec4 perpendicular = backward.cross3(normal);

    double length;
    // If both next and previous points are supplied then calculate the angle that bisects the angle
    // current, next, prev.
    if (next != null && prev != null && !Vec4.areColinear(prev, point, next)) {
      // Compute vector in the forward direction.
      Vec4 forward = next.subtract3(point);

      // Calculate the vector that bisects angle ABC.
      offset = forward.normalize3().add3(backward.normalize3());
      offset = offset.normalize3();

      // Compute the scalar triple product of the vector BC, the normal vector, and the offset
      // vector to
      // determine if the offset points to the left or the right of the control line.
      double tripleProduct = perpendicular.dot3(offset);
      if (tripleProduct < 0) {
        offset = offset.multiply3(-1);
      }

      // Determine the length of the offset vector that will keep the left and right lines parallel
      // to the control
      // line.
      Angle theta = backward.angleBetween3(offset);
      if (!Angle.ZERO.equals(theta)) length = halfWidth / theta.sin();
      else length = halfWidth;
    } else {
      offset = perpendicular.normalize3();
      length = halfWidth;
    }
    offset = offset.multiply3(length);

    // Determine the left and right points by applying the offset.
    Vec4 ptRight = point.add3(offset);
    Vec4 ptLeft = point.subtract3(offset);

    // Convert cartesian points to geographic.
    Position posLeft = globe.computePositionFromPoint(ptLeft);
    Position posRight = globe.computePositionFromPoint(ptRight);

    leftPositions.add(posLeft);
    rightPositions.add(posRight);
  }
Esempio n. 10
0
  /**
   * Compute the label's screen position from its geographic position.
   *
   * @param dc Current draw context.
   */
  protected void computeGeometry(DrawContext dc) {
    // Project the label position onto the viewport
    Position pos = this.getPosition();
    if (pos == null) return;

    this.placePoint = dc.computeTerrainPoint(pos.getLatitude(), pos.getLongitude(), 0);
    this.screenPlacePoint = dc.getView().project(this.placePoint);

    this.eyeDistance = this.placePoint.distanceTo3(dc.getView().getEyePoint());

    boolean orientationReversed = false;
    if (this.orientationPosition != null) {
      // Project the orientation point onto the screen
      Vec4 orientationPlacePoint =
          dc.computeTerrainPoint(
              this.orientationPosition.getLatitude(), this.orientationPosition.getLongitude(), 0);
      Vec4 orientationScreenPoint = dc.getView().project(orientationPlacePoint);

      this.rotation = this.computeRotation(this.screenPlacePoint, orientationScreenPoint);

      // The orientation is reversed if the orientation point falls to the right of the screen
      // point. Text is
      // never drawn upside down, so when the orientation is reversed the text flips vertically to
      // keep the text
      // right side up.
      orientationReversed = (orientationScreenPoint.x <= this.screenPlacePoint.x);
    }

    this.computeBoundsIfNeeded(dc);

    Offset offset = this.getOffset();
    Point2D offsetPoint =
        offset.computeOffset(this.bounds.getWidth(), this.bounds.getHeight(), null, null);

    // If a rotation is applied to the text, then rotate the offset as well. An offset in the x
    // direction
    // will move the text along the orientation line, and a offset in the y direction will move the
    // text
    // perpendicular to the orientation line.
    if (this.rotation != null) {
      double dy = offsetPoint.getY();

      // If the orientation is reversed we need to adjust the vertical offset to compensate for the
      // flipped
      // text. For example, if the offset normally aligns the top of the text with the place point
      // then without
      // this adjustment the bottom of the text would align with the place point when the
      // orientation is
      // reversed.
      if (orientationReversed) {
        dy = -(dy + this.bounds.getHeight());
      }

      Vec4 pOffset = new Vec4(offsetPoint.getX(), dy);
      Matrix rot = Matrix.fromRotationZ(this.rotation.multiply(-1));

      pOffset = pOffset.transformBy3(rot);

      offsetPoint = new Point((int) pOffset.getX(), (int) pOffset.getY());
    }

    int x = (int) (this.screenPlacePoint.x + offsetPoint.getX());
    int y = (int) (this.screenPlacePoint.y - offsetPoint.getY());

    this.screenPoint = new Point(x, y);
    this.screenExtent = this.computeTextExtent(x, y, this.rotation);
  }
Esempio n. 11
0
  protected void drawIcon(DrawContext dc) {
    if (this.getIconFilePath() == null) return;

    GL gl = dc.getGL();
    OGLStackHandler ogsh = new OGLStackHandler();

    try {
      // Initialize texture if necessary
      Texture iconTexture = dc.getTextureCache().getTexture(this.getIconFilePath());
      if (iconTexture == null) {
        this.initializeTexture(dc);
        iconTexture = dc.getTextureCache().getTexture(this.getIconFilePath());
        if (iconTexture == null) {
          String msg = Logging.getMessage("generic.ImageReadFailed");
          Logging.logger().finer(msg);
          return;
        }
      }
      gl.glDisable(GL.GL_DEPTH_TEST);

      double width = this.getScaledIconWidth();
      double height = this.getScaledIconHeight();

      // Load a parallel projection with xy dimensions (viewportWidth, viewportHeight)
      // into the GL projection matrix.
      java.awt.Rectangle viewport = dc.getView().getViewport();
      ogsh.pushProjectionIdentity(gl);
      double maxwh = width > height ? width : height;
      gl.glOrtho(0d, viewport.width, 0d, viewport.height, -0.6 * maxwh, 0.6 * maxwh);

      // Translate and scale
      ogsh.pushModelviewIdentity(gl);
      double scale = this.computeScale(viewport);
      Vec4 locationSW = this.computeLocation(viewport, scale);
      gl.glTranslated(locationSW.x(), locationSW.y(), locationSW.z());
      // Scale to 0..1 space
      gl.glScaled(scale, scale, 1);
      gl.glScaled(width, height, 1d);

      if (!dc.isPickingMode()) {
        gl.glEnable(GL.GL_BLEND);
        gl.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_ONE_MINUS_SRC_ALPHA);

        // Draw background color behind the map
        gl.glColor4ub(
            (byte) this.backColor.getRed(),
            (byte) this.backColor.getGreen(),
            (byte) this.backColor.getBlue(),
            (byte) (this.backColor.getAlpha() * this.getOpacity()));
        dc.drawUnitQuad();

        // Draw world map icon
        gl.glColor4d(1d, 1d, 1d, this.getOpacity());
        gl.glEnable(GL.GL_TEXTURE_2D);
        iconTexture.bind();

        TextureCoords texCoords = iconTexture.getImageTexCoords();
        dc.drawUnitQuad(texCoords);
        gl.glBindTexture(GL.GL_TEXTURE_2D, 0);
        gl.glDisable(GL.GL_TEXTURE_2D);

        // Draw crosshair for current location
        gl.glLoadIdentity();
        gl.glTranslated(locationSW.x(), locationSW.y(), locationSW.z());
        // Scale to width x height space
        gl.glScaled(scale, scale, 1);
        // Set color
        float[] colorRGB = this.color.getRGBColorComponents(null);
        gl.glColor4d(colorRGB[0], colorRGB[1], colorRGB[2], this.getOpacity());

        // Draw crosshair
        Position groundPos = this.computeGroundPosition(dc, dc.getView());
        if (groundPos != null) {
          int x = (int) (width * (groundPos.getLongitude().degrees + 180) / 360);
          int y = (int) (height * (groundPos.getLatitude().degrees + 90) / 180);
          int w = 10; // cross branch length
          // Draw
          gl.glBegin(GL.GL_LINE_STRIP);
          gl.glVertex3d(x - w, y, 0);
          gl.glVertex3d(x + w + 1, y, 0);
          gl.glEnd();
          gl.glBegin(GL.GL_LINE_STRIP);
          gl.glVertex3d(x, y - w, 0);
          gl.glVertex3d(x, y + w + 1, 0);
          gl.glEnd();
        }

        // Draw view footprint in map icon space
        if (this.showFootprint) {
          this.footPrintPositions = this.computeViewFootPrint(dc, 32);
          if (this.footPrintPositions != null) {
            gl.glBegin(GL.GL_LINE_STRIP);
            LatLon p1 = this.footPrintPositions.get(0);
            for (LatLon p2 : this.footPrintPositions) {
              int x = (int) (width * (p2.getLongitude().degrees + 180) / 360);
              int y = (int) (height * (p2.getLatitude().degrees + 90) / 180);
              // Draw
              if (LatLon.locationsCrossDateline(p1, p2)) {
                int y1 = (int) (height * (p1.getLatitude().degrees + 90) / 180);
                gl.glVertex3d(x < width / 2 ? width : 0, (y1 + y) / 2, 0);
                gl.glEnd();
                gl.glBegin(GL.GL_LINE_STRIP);
                gl.glVertex3d(x < width / 2 ? 0 : width, (y1 + y) / 2, 0);
              }
              gl.glVertex3d(x, y, 0);
              p1 = p2;
            }
            gl.glEnd();
          }
        }
        // Draw 1px border around and inside the map
        gl.glBegin(GL.GL_LINE_STRIP);
        gl.glVertex3d(0, 0, 0);
        gl.glVertex3d(width, 0, 0);
        gl.glVertex3d(width, height - 1, 0);
        gl.glVertex3d(0, height - 1, 0);
        gl.glVertex3d(0, 0, 0);
        gl.glEnd();
      } else {
        // Picking
        this.pickSupport.clearPickList();
        this.pickSupport.beginPicking(dc);
        // Where in the world are we picking ?
        Position pickPosition =
            computePickPosition(
                dc, locationSW, new Dimension((int) (width * scale), (int) (height * scale)));
        Color color = dc.getUniquePickColor();
        int colorCode = color.getRGB();
        this.pickSupport.addPickableObject(colorCode, this, pickPosition, false);
        gl.glColor3ub((byte) color.getRed(), (byte) color.getGreen(), (byte) color.getBlue());
        dc.drawUnitQuad();
        this.pickSupport.endPicking(dc);
        this.pickSupport.resolvePick(dc, dc.getPickPoint(), this);
      }
    } finally {
      dc.restoreDefaultDepthTesting();
      dc.restoreDefaultCurrentColor();
      if (dc.isPickingMode()) dc.restoreDefaultBlending();
      ogsh.pop(gl);
    }
  }
Esempio n. 12
0
  /**
   * Determine the positions that make up the arrowhead.
   *
   * @param dc Current draw context.
   * @param startPosition Position of the arrow's base.
   * @param endPosition Position of the arrow head tip.
   * @return Positions that define the arrowhead.
   */
  protected List<Position> computeArrowheadPositions(
      DrawContext dc, Position startPosition, Position endPosition) {
    Globe globe = dc.getGlobe();

    // Arrowhead looks like this:
    //                  _
    //        A\         | 1/2 width
    // ________B\       _|
    // Pt. 1    /
    //        C/
    //         | |
    //      Length

    Vec4 p1 = globe.computePointFromPosition(startPosition);
    Vec4 pB = globe.computePointFromPosition(endPosition);

    // Find vector in the direction of the arrow
    Vec4 vB1 = p1.subtract3(pB);

    double arrowLengthFraction = this.getArrowLength();

    // Find the point at the base of the arrowhead
    Vec4 arrowBase = pB.add3(vB1.multiply3(arrowLengthFraction));

    Vec4 normal = globe.computeSurfaceNormalAtPoint(arrowBase);

    // Compute the length of the arrowhead
    double arrowLength = vB1.getLength3() * arrowLengthFraction;
    double arrowHalfWidth = arrowLength * this.getArrowAngle().tanHalfAngle();

    // Compute a vector perpendicular to the segment and the normal vector
    Vec4 perpendicular = vB1.cross3(normal);
    perpendicular = perpendicular.normalize3().multiply3(arrowHalfWidth);

    // Find points A and C
    Vec4 pA = arrowBase.add3(perpendicular);
    Vec4 pC = arrowBase.subtract3(perpendicular);

    return TacticalGraphicUtil.asPositionList(globe, pA, pB, pC);
  }
Esempio n. 13
0
  /**
   * Compute the positions of the arrow head of the graphic's legs.
   *
   * @param dc Current draw context
   * @param base Position of the arrow's starting point.
   * @param tip Position of the arrow head tip.
   * @param arrowLength Length of the arrowhead as a fraction of the total line length.
   * @param arrowAngle Angle of the arrow head.
   * @return Positions required to draw the arrow head.
   */
  protected List<Position> computeArrowheadPositions(
      DrawContext dc, Position base, Position tip, double arrowLength, Angle arrowAngle) {
    // Build a triangle to represent the arrowhead. The triangle is built from two vectors, one
    // parallel to the
    // segment, and one perpendicular to it.

    Globe globe = dc.getGlobe();

    Vec4 ptA = globe.computePointFromPosition(base);
    Vec4 ptB = globe.computePointFromPosition(tip);

    // Compute parallel component
    Vec4 parallel = ptA.subtract3(ptB);

    Vec4 surfaceNormal = globe.computeSurfaceNormalAtPoint(ptB);

    // Compute perpendicular component
    Vec4 perpendicular = surfaceNormal.cross3(parallel);

    double finalArrowLength = arrowLength * parallel.getLength3();
    double arrowHalfWidth = finalArrowLength * arrowAngle.tanHalfAngle();

    perpendicular = perpendicular.normalize3().multiply3(arrowHalfWidth);
    parallel = parallel.normalize3().multiply3(finalArrowLength);

    // Compute geometry of direction arrow
    Vec4 vertex1 = ptB.add3(parallel).add3(perpendicular);
    Vec4 vertex2 = ptB.add3(parallel).subtract3(perpendicular);

    return TacticalGraphicUtil.asPositionList(globe, vertex1, vertex2, ptB);
  }
Esempio n. 14
0
  // Rendering
  public void draw(DrawContext dc) {
    GL gl = dc.getGL();

    boolean attribsPushed = false;
    boolean modelviewPushed = false;
    boolean projectionPushed = false;

    try {
      gl.glPushAttrib(
          GL.GL_DEPTH_BUFFER_BIT
              | GL.GL_COLOR_BUFFER_BIT
              | GL.GL_ENABLE_BIT
              | GL.GL_TEXTURE_BIT
              | GL.GL_TRANSFORM_BIT
              | GL.GL_VIEWPORT_BIT
              | GL.GL_CURRENT_BIT);
      attribsPushed = true;

      gl.glDisable(GL.GL_TEXTURE_2D); // no textures

      gl.glEnable(GL.GL_BLEND);
      gl.glBlendFunc(GL.GL_SRC_ALPHA, GL.GL_ONE_MINUS_SRC_ALPHA);
      gl.glDisable(GL.GL_DEPTH_TEST);

      double width = this.size.width;
      double height = this.size.height;

      // Load a parallel projection with xy dimensions (viewportWidth, viewportHeight)
      // into the GL projection matrix.
      java.awt.Rectangle viewport = dc.getView().getViewport();
      gl.glMatrixMode(javax.media.opengl.GL.GL_PROJECTION);
      gl.glPushMatrix();
      projectionPushed = true;
      gl.glLoadIdentity();
      double maxwh = width > height ? width : height;
      gl.glOrtho(0d, viewport.width, 0d, viewport.height, -0.6 * maxwh, 0.6 * maxwh);

      gl.glMatrixMode(GL.GL_MODELVIEW);
      gl.glPushMatrix();
      modelviewPushed = true;
      gl.glLoadIdentity();

      // Scale to a width x height space
      // located at the proper position on screen
      double scale = this.computeScale(viewport);
      Vec4 locationSW = this.computeLocation(viewport, scale);
      gl.glTranslated(locationSW.x(), locationSW.y(), locationSW.z());
      gl.glScaled(scale, scale, 1);

      // Compute scale size in real world
      Position referencePosition = dc.getViewportCenterPosition();
      if (referencePosition != null) {
        Vec4 groundTarget = dc.getGlobe().computePointFromPosition(referencePosition);
        Double distance = dc.getView().getEyePoint().distanceTo3(groundTarget);
        this.pixelSize = dc.getView().computePixelSizeAtDistance(distance);
        Double scaleSize = this.pixelSize * width * scale; // meter
        String unitLabel = "m";
        if (this.unit.equals(UNIT_METRIC)) {
          if (scaleSize > 10000) {
            scaleSize /= 1000;
            unitLabel = "Km";
          }
        } else if (this.unit.equals(UNIT_IMPERIAL)) {
          scaleSize *= 3.280839895; // feet
          unitLabel = "ft";
          if (scaleSize > 5280) {
            scaleSize /= 5280;
            unitLabel = "mile(s)";
          }
        }

        // Rounded division size
        int pot = (int) Math.floor(Math.log10(scaleSize));
        if (!Double.isNaN(pot)) {
          int digit = Integer.parseInt(String.format("%.0f", scaleSize).substring(0, 1));
          double divSize = digit * Math.pow(10, pot);
          if (digit >= 5) divSize = 5 * Math.pow(10, pot);
          else if (digit >= 2) divSize = 2 * Math.pow(10, pot);
          double divWidth = width * divSize / scaleSize;

          // Draw scale
          if (!dc.isPickingMode()) {
            // Set color using current layer opacity
            Color backColor = this.getBackgroundColor(this.color);
            float[] colorRGB = backColor.getRGBColorComponents(null);
            gl.glColor4d(
                colorRGB[0],
                colorRGB[1],
                colorRGB[2],
                (double) backColor.getAlpha() / 255d * this.getOpacity());
            gl.glTranslated((width - divWidth) / 2, 0d, 0d);
            this.drawScale(dc, divWidth, height);

            colorRGB = this.color.getRGBColorComponents(null);
            gl.glColor4d(colorRGB[0], colorRGB[1], colorRGB[2], this.getOpacity());
            gl.glTranslated(-1d / scale, 1d / scale, 0d);
            this.drawScale(dc, divWidth, height);

            // Draw label
            String label = String.format("%.0f ", divSize) + unitLabel;
            gl.glLoadIdentity();
            gl.glDisable(GL.GL_CULL_FACE);
            drawLabel(
                dc,
                label,
                locationSW.add3(
                    new Vec4(divWidth * scale / 2 + (width - divWidth) / 2, height * scale, 0)));
          } else {
            // Picking
            this.pickSupport.clearPickList();
            this.pickSupport.beginPicking(dc);
            // Draw unique color across the map
            Color color = dc.getUniquePickColor();
            int colorCode = color.getRGB();
            // Add our object(s) to the pickable list
            this.pickSupport.addPickableObject(colorCode, this, referencePosition, false);
            gl.glColor3ub((byte) color.getRed(), (byte) color.getGreen(), (byte) color.getBlue());
            gl.glTranslated((width - divWidth) / 2, 0d, 0d);
            this.drawRectangle(dc, divWidth, height);
            // Done picking
            this.pickSupport.endPicking(dc);
            this.pickSupport.resolvePick(dc, dc.getPickPoint(), this);
          }
        }
      }
    } finally {
      if (projectionPushed) {
        gl.glMatrixMode(GL.GL_PROJECTION);
        gl.glPopMatrix();
      }
      if (modelviewPushed) {
        gl.glMatrixMode(GL.GL_MODELVIEW);
        gl.glPopMatrix();
      }
      if (attribsPushed) gl.glPopAttrib();
    }
  }