77 lines
2.1 KiB
Java
77 lines
2.1 KiB
Java
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package net.osmand.data;
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import java.util.ArrayList;
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import java.util.List;
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import net.osmand.osm.MapUtils;
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import net.osmand.osm.Node;
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import net.osmand.osm.Way;
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public class MapAlgorithms {
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public static void simplifyDouglasPeucker(List<Node> n, int zoom, int epsilon, Way w){
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ArrayList<Integer> l = new ArrayList<Integer>();
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int first = 0;
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while(first < n.size()){
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if(n.get(first) != null){
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break;
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}
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first++;
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}
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int last = n.size() - 1;
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while (last >= 0) {
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if (n.get(last) != null) {
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break;
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}
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last--;
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}
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if(last - first < 1){
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return;
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}
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boolean cycle = n.get(first).getId() == n.get(last).getId();
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simplifyDouglasPeucker(n, zoom, epsilon, l, first, cycle ? last - 1: last);
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w.addNode(n.get(first));
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for (int i = 0; i < l.size(); i++) {
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w.addNode(n.get(l.get(i)));
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}
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if (cycle) {
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w.addNode(n.get(first));
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}
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}
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private static void simplifyDouglasPeucker(List<Node> n, int zoom, int epsilon, List<Integer> ints, int start, int end){
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double dmax = -1;
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int index = -1;
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for (int i = start + 1; i <= end - 1; i++) {
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if(n.get(i) == null){
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continue;
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}
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double d = orthogonalDistance(zoom, n.get(start), n.get(end), n.get(i));// calculate distance from line
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if (d > dmax) {
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dmax = d;
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index = i;
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}
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}
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if(dmax >= epsilon){
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simplifyDouglasPeucker(n, zoom, epsilon, ints, start, index);
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simplifyDouglasPeucker(n, zoom, epsilon, ints, index, end);
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} else {
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ints.add(end);
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}
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}
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private static double orthogonalDistance(int zoom, Node nodeLineStart, Node nodeLineEnd, Node node) {
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double x1 = MapUtils.getTileNumberX(zoom, nodeLineStart.getLongitude());
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double y1 = MapUtils.getTileNumberY(zoom, nodeLineStart.getLatitude());
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double x2 = MapUtils.getTileNumberX(zoom, nodeLineEnd.getLongitude());
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double y2 = MapUtils.getTileNumberY(zoom, nodeLineEnd.getLatitude());
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double x = MapUtils.getTileNumberX(zoom, node.getLongitude());
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double y = MapUtils.getTileNumberY(zoom, node.getLatitude());
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double A = x - x1;
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double B = y - y1;
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double C = x2 - x1;
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double D = y2 - y1;
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return Math.abs(A * D - C * B) / Math.sqrt(C * C + D * D);
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}
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}
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