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2024-01-02 7b595546af704983dbafcd0d385c8768ddacefc2
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package PbuliClass;
import java.awt.geom.Point2D;
import java.util.List;
/**¸ÃÀàÓÃÓÚÅжϵãÊÇ·ñÔÚ¶à±ßÐÎÄÚ*/
public class IsPtInPoly {
    /** 
    * ÅжϵãÊÇ·ñÔÚ¶à±ßÐÎÄÚ 
    * shapeÐÎ×´
    * @param point ¼ì²âµã 
    * @param pts   ¶à±ßÐεĶ¥µã¼¯ºÏ 
    * @return µãÔÚ¶à±ßÐÎÄÚ·µ»Øtrue,·ñÔò·µ»Øfalse 
    */  
    public static boolean inPoly(Point2D.Double point, List<Point2D.Double> pts){       
       boolean boundOrVertex = true; //Èç¹ûµãλÓÚ¶à±ßÐεĶ¥µã»ò±ßÉÏ£¬Ò²Ëã×öµãÔÚ¶à±ßÐÎÄÚ£¬Ö±½Ó·µ»Øtrue       
       int N = pts.size(); 
       int intersectCount = 0;
       double precision = 2e-10; //¸¡µãÀàÐͼÆËãʱºòÓë0±È½ÏʱºòµÄÈݲ
       Point2D.Double p1, p2;
       Point2D.Double p = point; //µ±Ç°µã  
         
       p1 = pts.get(0);   
       for(int i = 1; i <= N; ++i){      
           if(p.equals(p1)){  
               return boundOrVertex;
           }  
           p2 = pts.get(% N);        
           if(p.< Math.min(p1.x, p2.x) || p.> Math.max(p1.x, p2.x)){                
               p1 = p2;   
               continue;
           }  
             
           if(p.> Math.min(p1.x, p2.x) && p.< Math.max(p1.x, p2.x)){
               if(p.<= Math.max(p1.y, p2.y)){                 
                   if(p1.== p2.&& p.>= Math.min(p1.y, p2.y)){
                       return boundOrVertex;  
                   }  
                     
                   if(p1.== p2.y){                       
                       if(p1.== p.y){
                           return boundOrVertex;  
                       }else{
                           ++intersectCount;  
                       }   
                   }else{
                       double xinters = (p.- p1.x) * (p2.- p1.y) / (p2.- p1.x) + p1.y;                       
                       if(Math.abs(p.- xinters) < precision){
                           return boundOrVertex;  
                       }  
                         
                       if(p.< xinters){ 
                           ++intersectCount;  
                       }   
                   }  
               }  
           }else{                 
               if(p.== p2.&& p.<= p2.y){                    
                   Point2D.Double p3 = pts.get((i+1) % N);                      
                   if(p.>= Math.min(p1.x, p3.x) && p.<= Math.max(p1.x, p3.x)){
                       ++intersectCount;  
                   }else{  
                       intersectCount += 2;  
                   }  
               }  
           }              
           p1 = p2;  
       }  
         
       if(intersectCount % 2 == 0){
           return false;  
       } else { 
           return true;  
       }  
        
    }
 
}