Region.java

  1. package gov.usgs.earthquake.qdm;

  3. import java.util.ArrayList;

  5. /**
  6.  * A polygon without holes.
  7.  *
  8.  * Points are assumed to use x=longitude, y=latitude.
  9.  * A "default" region has no boundary points, and contains all points.
  10.  */
  11. public class Region {

  13.   /** String for net id */
  14.   public String netid;
  15.   /** String for region id */
  16.   public String regionid;

  18.   /** Arraylist of points */
  19.   public ArrayList<Point> points;

  21.   /**
  22.    * Region constructor
  23.    * @param netid string
  24.    * @param regionid string
  25.    */
  26.   public Region(String netid, String regionid) {
  27.     this.netid = netid;
  28.     this.regionid = regionid;
  29.     this.points = new ArrayList<Point>();
  30.   }

  32.   /**
  33.    * Method to determine if this lat-lon in this region? In or out algorithm taken
  34.    * from an algorithm by Edwards and Coleman of Oak Ridge Lab, version for BNL by
  35.    * Benkovitz translated to C by Andy Michael and into Java by Alan Jones.
  36.    *
  37.    * @param xy point
  38.    * @return bool if point is in region
  39.    */
  40.   public boolean inpoly(Point xy) {
  41.     int in;
  42.     double sine;
  43.     boolean bool = false;
  44.     int inside = 0;
  45.     int nvert = this.points.size();
  46.     // If there are no points in the region, assume default region
  47.     // and declare the point inside
  48.     if (nvert == 0)
  49.       return true;
  50.     Point p[] = (Point[]) this.points.toArray(new Point[0]);
  51.     double x = xy.x;
  52.     double y = xy.y;
  53.     for (int i = 0; i < nvert; ++i) {
  54.       in = i + 1;
  55.       if (in >= nvert)
  56.         in = 0;
  57.       if (p[in].y == p[i].y && p[in].x == p[i].x)
  58.         continue;
  59.       sine = (x - p[i].x) * (p[in].y - p[i].y) - (y - p[i].y) * (p[in].x - p[i].x);
  60.       if (sine == 0) {
  61.         if (((x - p[i].x) * (p[in].x - p[i].x) + (y - p[i].y) * (p[in].y - p[i].y))
  62.             * ((x - p[in].x) * (p[in].x - p[i].x) + (y - p[in].y) * (p[in].y - p[i].y)) > 0)
  63.           continue;
  64.         return true;
  65.       }
  66.       if (y > p[in].y && y <= p[i].y && sine < 0 || y <= p[in].y && y > p[i].y && sine > 0) {
  67.         bool = !bool;
  68.       }
  69.     }
  70.     if (bool)
  71.       inside = 1;
  72.     if (inside != 0)
  73.       return true;
  74.     else
  75.       return false;
  76.   }

  78. }
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