public Vec4 terrainPoint;

protected void computeSymbolPoints(DrawContext dc, OrderedSymbol osym)
{
    osym.placePoint = null;
    osym.screenPoint = null;
    osym.terrainPoint = null;
    osym.eyeDistance = 0;

    Position pos = this.getPosition();
    if (pos == null)
        return;

    if (this.altitudeMode == WorldWind.CLAMP_TO_GROUND || dc.is2DGlobe())
    {
        osym.placePoint = dc.computeTerrainPoint(pos.getLatitude(), pos.getLongitude(), 0);
    }
    else if (this.altitudeMode == WorldWind.RELATIVE_TO_GROUND)
    {
        osym.placePoint = dc.computeTerrainPoint(pos.getLatitude(), pos.getLongitude(), pos.getAltitude());
    }
    else // Default to ABSOLUTE
    {
        double height = pos.getElevation() * dc.getVerticalExaggeration();
        osym.placePoint = dc.getGlobe().computePointFromPosition(pos.getLatitude(), pos.getLongitude(), height);
    }

    if (osym.placePoint == null)
        return;

    // Compute the symbol's screen location the distance between the eye point and the place point.
    osym.screenPoint = dc.getView().project(osym.placePoint);
    osym.eyeDistance = osym.placePoint.distanceTo3(dc.getView().getEyePoint());

    // Compute a terrain point if needed.
    if (this.isLineEnabled() && this.altitudeMode != WorldWind.CLAMP_TO_GROUND && !dc.is2DGlobe())
        osym.terrainPoint = dc.computeTerrainPoint(pos.getLatitude(), pos.getLongitude(), 0);

}

boolean lineEnabled = true;


double lineWidth = 1;
protected int linePickWidth = 10;
Color lineColor = Color.white;

/**
 * Indicates whether a line from the placemark point to the corresponding position on the terrain is drawn.
 *
 * @return true if the line is drawn, otherwise false.
 */
public boolean isLineEnabled()
{
    return lineEnabled;
}

/**
 * Specifies whether a line from the placemark point to the corresponding position on the terrain is drawn.
 *
 * @param lineEnabled true if the line is drawn, otherwise false.
 */
public void setLineEnabled(boolean lineEnabled)
{
    this.lineEnabled = lineEnabled;
}

/**
 * Determines whether the placemark's optional line should be drawn and whether it intersects the view frustum.
 *
 * @param dc the current draw context.
 *
 * @return true if the line should be drawn and it intersects the view frustum, otherwise false.
 */
protected boolean isDrawLine(DrawContext dc, OrderedSymbol opm)
{
    if (!this.isLineEnabled() || dc.is2DGlobe() || this.getAltitudeMode() == WorldWind.CLAMP_TO_GROUND
        || opm.terrainPoint == null)
        return false;

    if (dc.isPickingMode())
        return dc.getPickFrustums().intersectsAny(opm.placePoint, opm.terrainPoint);
    else
        return dc.getView().getFrustumInModelCoordinates().intersectsSegment(opm.placePoint, opm.terrainPoint);
}




/**
 * Draws the placemark's line.
 *
 * @param dc             the current draw context.
 * @param pickCandidates the pick support object to use when adding this as a pick candidate.
 */
protected void drawLine(DrawContext dc, PickSupport pickCandidates, OrderedSymbol opm)
{
    GL2 gl = dc.getGL().getGL2(); // GL initialization checks for GL2 compatibility.

    if ((!dc.isDeepPickingEnabled()))
        gl.glEnable(GL.GL_DEPTH_TEST);
    gl.glDepthFunc(GL.GL_LEQUAL);
    gl.glDepthMask(true);

    try
    {
        dc.getView().pushReferenceCenter(dc, opm.placePoint); // draw relative to the place point

        this.setLineWidth(dc);
        this.setLineColor(dc, pickCandidates);

        gl.glBegin(GL2.GL_LINE_STRIP);
        gl.glVertex3d(Vec4.ZERO.x, Vec4.ZERO.y, Vec4.ZERO.z);
        gl.glVertex3d(opm.terrainPoint.x - opm.placePoint.x, opm.terrainPoint.y - opm.placePoint.y,
            opm.terrainPoint.z - opm.placePoint.z);
        gl.glEnd();
    }
    finally
    {
        dc.getView().popReferenceCenter(dc);
    }
}


/**
 * Sets the width of the placemark's line during rendering.
 *
 * @param dc the current draw context.
 */
protected void setLineWidth(DrawContext dc)
{
    Double lineWidth = this.lineWidth;
    if (lineWidth != null)
    {
        GL gl = dc.getGL();

        if (dc.isPickingMode())
        {
            gl.glLineWidth(lineWidth.floatValue() + linePickWidth);
        }
        else
            gl.glLineWidth(lineWidth.floatValue());

        if (!dc.isPickingMode())
        {
            gl.glHint(GL.GL_LINE_SMOOTH_HINT, GL.GL_FASTEST);
            gl.glEnable(GL.GL_LINE_SMOOTH);
        }
    }
}


/**
 * Sets the color of the placemark's line during rendering.
 *
 * @param dc             the current draw context.
 * @param pickCandidates the pick support object to use when adding this as a pick candidate.
 */
protected void setLineColor(DrawContext dc, PickSupport pickCandidates)
{
    GL2 gl = dc.getGL().getGL2(); // GL initialization checks for GL2 compatibility.

    if (!dc.isPickingMode())
    {
        Color color = this.lineColor;
        gl.glColor4ub((byte) color.getRed(), (byte) color.getGreen(), (byte) color.getBlue(),
            (byte) color.getAlpha());
    }
    else
    {
        Color pickColor = dc.getUniquePickColor();
        Object delegateOwner = this.getDelegateOwner();
        pickCandidates.addPickableObject(pickColor.getRGB(), delegateOwner != null ? delegateOwner : this,
            this.getPosition());
        gl.glColor3ub((byte) pickColor.getRed(), (byte) pickColor.getGreen(), (byte) pickColor.getBlue());
    }
}

boolean drawLine = this.isDrawLine(dc, osym);
if (drawLine)
    this.drawLine(dc, pickCandidates, osym);