sascha@1794: package de.intevation.flys.geom;
sascha@1794: 
sascha@1794: import gnu.trove.TDoubleArrayList;
sascha@1794: 
sascha@1794: import java.io.Serializable;
sascha@1794: 
sascha@1794: import java.awt.Shape;
sascha@1794: 
sascha@1794: import java.awt.geom.Path2D;
sascha@1794: import java.awt.geom.Point2D;
sascha@1794: 
sascha@1794: import java.util.ArrayList;
sascha@1794: import java.util.List;
sascha@1794: import java.util.Arrays;
sascha@1794: import java.util.Comparator;
sascha@1794: import java.util.Collections;
sascha@1794: 
sascha@1794: public class Polygon2D
sascha@1794: implements   Serializable
sascha@1794: {
sascha@1794:     public static final Comparator<Point2D> POINT_X_CMP =
sascha@1794:         new Comparator<Point2D>() {
sascha@1794:             public int compare(Point2D a, Point2D b) {
sascha@1794:                 double d = a.getX() - b.getX();
sascha@1794:                 if (d < 0d) return -1;
sascha@1794:                 return d > 0d ? + 1 : 0;
sascha@1794:             }
sascha@1794:         };
sascha@1794: 
sascha@1794:     public static final Comparator<Point2D []> FIRST_POINT_X =
sascha@1794:         new Comparator<Point2D []>() {
sascha@1794:             public int compare(Point2D [] a, Point2D [] b) {
sascha@1794:                 if (a.length == 0) return -1; // should not happen.
sascha@1794:                 if (b.length == 0) return +1; // should not happen.
sascha@1794:                 double d = a[0].getX() - b[0].getX();
sascha@1794:                 if (d < 0d) return -1;
sascha@1794:                 return d > 0d ? + 1 : 0;
sascha@1794:             }
sascha@1794:         };
sascha@1794: 
sascha@1794:     protected TDoubleArrayList xs;
sascha@1794:     protected TDoubleArrayList ys;
sascha@1794: 
sascha@1794:     public Polygon2D() {
sascha@1794:         xs = new TDoubleArrayList();
sascha@1794:         ys = new TDoubleArrayList();
sascha@1794:     }
sascha@1794: 
sascha@1794:     public void add(double x, double y) {
sascha@1794:         xs.add(x);
sascha@1794:         ys.add(y);
sascha@1794:     }
sascha@1794: 
sascha@1794:     public double area() {
sascha@1794:         double area = 0d;
sascha@1794: 
sascha@1794: 		for (int i = 0, N = xs.size(); i < N; ++i) {
sascha@1794: 			int j = (i + 1) % N;
sascha@1794: 			area += xs.getQuick(i)*ys.getQuick(j);
sascha@1794: 			area -= xs.getQuick(j)*ys.getQuick(i);
sascha@1794: 		}
sascha@1794: 
sascha@1794:         return 0.5d*area;
sascha@1794:     }
sascha@1794: 
sascha@1794:     public Shape toShape() {
sascha@1794:         Path2D.Double path = new Path2D.Double();
sascha@1794: 
sascha@1794:         int N = xs.size();
sascha@1794: 
sascha@1794:         if (N > 0) {
sascha@1794:             path.moveTo(xs.getQuick(0), ys.getQuick(0));
sascha@1794:             for (int i = 1; i < N; ++i) {
sascha@1794:                 path.lineTo(xs.getQuick(i), ys.getQuick(i));
sascha@1794:             }
sascha@1794:             path.closePath();
sascha@1794:         }
sascha@1794: 
sascha@1794:         return path;
sascha@1794:     }
sascha@1794: 
sascha@1794:     protected static List<Point2D []> splitByNaNs(
sascha@1794:         double [] xs,
sascha@1794:         double [] ys
sascha@1794:     ) {
sascha@1794:         List<Point2D []> parts = new ArrayList<Point2D []>();
sascha@1794: 
sascha@1794:         List<Point2D> tmp = new ArrayList<Point2D>(xs.length);
sascha@1794: 
sascha@1794:         for (int i = 0; i < xs.length; ++i) {
sascha@1794:             double x = xs[i];
sascha@1794:             double y = ys[i];
sascha@1794: 
sascha@1794:             if (Double.isNaN(x) || Double.isNaN(y)) {
sascha@1794:                 if (!tmp.isEmpty()) {
sascha@1794:                     Point2D [] part = new Point2D[tmp.size()];
sascha@1794:                     parts.add(tmp.toArray(part));
sascha@1794:                     tmp.clear();
sascha@1794:                 }
sascha@1794:             }
sascha@1794:             else {
sascha@1794:                 tmp.add(new Point2D.Double(x, y));
sascha@1794:             }
sascha@1794:         }
sascha@1794: 
sascha@1794:         if (!tmp.isEmpty()) {
sascha@1794:             Point2D [] part = new Point2D[tmp.size()];
sascha@1794:             parts.add(tmp.toArray(part));
sascha@1794:         }
sascha@1794: 
sascha@1794:         return parts;
sascha@1794:     }
sascha@1794: 
sascha@1794:     public static void createPolygons(
sascha@1794:         double [] xAs, double [] yAs,
sascha@1794:         double [] xBs, double [] yBs,
sascha@1794:         List<Polygon2D> positives,
sascha@1794:         List<Polygon2D> negatives
sascha@1794:     ) {
sascha@1794:         if (xAs.length == 0 || xBs.length == 0) {
sascha@1794:             return;
sascha@1794:         }
sascha@1794: 
sascha@1794:         List<Point2D []> splAs = splitByNaNs(xAs, yAs);
sascha@1794:         List<Point2D []> splBs = splitByNaNs(xBs, yBs);
sascha@1794: 
sascha@1794:         // They feeded us with NaNs only.
sascha@1794:         if (splAs.isEmpty() || splBs.isEmpty()) {
sascha@1794:             return;
sascha@1794:         }
sascha@1794: 
sascha@1794:         // Sort each part by x to ensure that the first
sascha@1794:         // is the smallest.
sascha@1794:         for (Point2D [] splA: splAs) {
sascha@1794:             Arrays.sort(splA, POINT_X_CMP);
sascha@1794:         }
sascha@1794: 
sascha@1794:         for (Point2D [] splB: splBs) {
sascha@1794:             Arrays.sort(splB, POINT_X_CMP);
sascha@1794:         }
sascha@1794: 
sascha@1794:         // Now sort all parts by there first elements.
sascha@1794:         // Should be good enough to find overlapping regions.
sascha@1794:         Collections.sort(splAs, FIRST_POINT_X);
sascha@1794:         Collections.sort(splBs, FIRST_POINT_X);
sascha@1794: 
sascha@1794:         // Check if the two series intersect at all.
sascha@1794:         // If no then there will be no area between them.
sascha@1794: 
sascha@1794:         Point2D [] p1 = splAs.get(0);
sascha@1794:         Point2D [] p2 = splBs.get(splBs.size()-1);
sascha@1794: 
sascha@1794:         // First of As greater than last of Bs.
sascha@1794:         if (POINT_X_CMP.compare(p1[0], p2[p2.length-1]) > 0) {
sascha@1794:             return;
sascha@1794:         }
sascha@1794: 
sascha@1794:         p2 = splAs.get(splAs.size()-1);
sascha@1794:         p1 = splBs.get(0);
sascha@1794: 
sascha@1794:         //  First of Bs greater than last of As.
sascha@1794:         if (POINT_X_CMP.compare(p1[0], p2[p2.length-1]) > 0) {
sascha@1794:             return;
sascha@1794:         }
sascha@1794: 
sascha@1794:         // TODO: Intersect/split the two series parts.
sascha@1794: 
sascha@1794:     }
sascha@1794: }
sascha@1794: // vim:set ts=4 sw=4 si et sta sts=4 fenc=utf8 :