contourlinepolygon.java

world wind java sdk 源码

/*
Copyright (C) 2001, 2009 United States Government
as represented by the Administrator of the
National Aeronautics and Space Administration.
All Rights Reserved.
*/
package gov.nasa.worldwind.render;

import gov.nasa.worldwind.geom.*;
import gov.nasa.worldwind.globes.Globe;
import gov.nasa.worldwind.util.Logging;
import gov.nasa.worldwind.util.measure.AreaMeasurer;

import java.util.ArrayList;

/**
 * Renders a contour line on the terrain at a given elevation. The controur line extent
 * is bounded by a polygon defined by a list of <code>LatLon</code>.
 *
 * @author Patrick Murris
 * @version $Id: ContourLinePolygon.java 8687 2009-02-01 03:43:41Z patrickmurris $
 */
public class ContourLinePolygon extends ContourLine
{
    private ArrayList<? extends LatLon> positions;

    public ContourLinePolygon()
    {
        super();
    }

    public ContourLinePolygon(double elevation)
    {
        super(elevation);
    }

    public ContourLinePolygon(double elevation, ArrayList<? extends LatLon> positions)
    {
        super(elevation);
        this.setPositions(positions);
    }

    /**
     * Get the list of <code>LatLon</code> that describe the current bounding polygon.
     * @return the list of <code>LatLon</code> that describe the current bounding polygon.
     */
    public ArrayList<? extends LatLon> getPositions()
    {
        return this.positions;
    }

    /**
     * Set the list of <code>LatLon</code> that describes a closed polygon - one which last position
     * is equal to the first, used to delineate the extent of the contour line.
     *
     * @param positions the list of <code>LatLon</code> that describe a closed polygon.
     */
    public void setPositions(ArrayList<? extends LatLon> positions)
    {
        if (positions == null)
        {
            String message = Logging.getMessage("nullValue.PositionsListIsNull");
            Logging.logger().severe(message);
            throw new IllegalArgumentException(message);
        }

        this.positions = positions;
        this.setSector(Sector.boundingSector(positions));
        this.update();
    }

    /**
     * Filters the given intersection segments list according to some criteria - here the
     * inclusion inside the current polygon.
     * 
     * @param dc the current <code>DrawContext</code>
     * @param list the list of <code>Intersection</code> to be filtered.
     * @return the filtered list.
     */
    protected ArrayList<Intersection> filterIntersections(DrawContext dc, ArrayList<Intersection> list)
    {
        // Filter against the bounding sector first
        list = super.filterIntersections(dc, list);
        
        // Filter the remaining segments against the polygon
        if (this.getPositions() == null)
            return list;

        Globe globe = dc.getGlobe();
        int i = 0;
        while (i < list.size())
        {
            if (AreaMeasurer.isLocationInside(globe.computePositionFromPoint(list.get(i).getIntersectionPoint()),
                this.positions) &&
                AreaMeasurer.isLocationInside(globe.computePositionFromPoint(list.get(i + 1).getIntersectionPoint()),
                this.positions))
                // Keep segment
                i += 2;
            else
            {
                // Remove segment
                list.remove(i);
                list.remove(i);
            }
        }
        return list;
    }

}