package PbuliClass;
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import java.awt.geom.Point2D;
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import java.util.List;
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/**¸ÃÀàÓÃÓÚÅжϵãÊÇ·ñÔÚ¶à±ßÐÎÄÚ*/
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public class IsPtInPoly {
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/**
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* ÅжϵãÊÇ·ñÔÚ¶à±ßÐÎÄÚ
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* shapeÐÎ×´
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* @param point ¼ì²âµã
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* @param pts ¶à±ßÐεĶ¥µã¼¯ºÏ
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* @return µãÔÚ¶à±ßÐÎÄÚ·µ»Øtrue,·ñÔò·µ»Øfalse
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*/
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public static boolean inPoly(Point2D.Double point, List<Point2D.Double> pts){
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boolean boundOrVertex = true; //Èç¹ûµãλÓÚ¶à±ßÐεĶ¥µã»ò±ßÉÏ£¬Ò²Ëã×öµãÔÚ¶à±ßÐÎÄÚ£¬Ö±½Ó·µ»Øtrue
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int N = pts.size();
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int intersectCount = 0;
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double precision = 2e-10; //¸¡µãÀàÐͼÆËãʱºòÓë0±È½ÏʱºòµÄÈݲî
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Point2D.Double p1, p2;
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Point2D.Double p = point; //µ±Ç°µã
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p1 = pts.get(0);
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for(int i = 1; i <= N; ++i){
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if(p.equals(p1)){
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return boundOrVertex;
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}
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p2 = pts.get(i % N);
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if(p.x < Math.min(p1.x, p2.x) || p.x > Math.max(p1.x, p2.x)){
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p1 = p2;
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continue;
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}
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if(p.x > Math.min(p1.x, p2.x) && p.x < Math.max(p1.x, p2.x)){
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if(p.y <= Math.max(p1.y, p2.y)){
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if(p1.x == p2.x && p.y >= Math.min(p1.y, p2.y)){
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return boundOrVertex;
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}
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if(p1.y == p2.y){
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if(p1.y == p.y){
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return boundOrVertex;
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}else{
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++intersectCount;
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}
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}else{
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double xinters = (p.x - p1.x) * (p2.y - p1.y) / (p2.x - p1.x) + p1.y;
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if(Math.abs(p.y - xinters) < precision){
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return boundOrVertex;
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}
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if(p.y < xinters){
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++intersectCount;
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}
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}
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}
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}else{
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if(p.x == p2.x && p.y <= p2.y){
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Point2D.Double p3 = pts.get((i+1) % N);
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if(p.x >= Math.min(p1.x, p3.x) && p.x <= Math.max(p1.x, p3.x)){
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++intersectCount;
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}else{
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intersectCount += 2;
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}
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}
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}
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p1 = p2;
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}
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if(intersectCount % 2 == 0){
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return false;
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} else {
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return true;
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}
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}
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}
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