判断经纬度是否存在于某一个多边形的区域内(亲测有效)

矫情吗；* 2023-06-28 09:53 15阅读 0赞

/**
         * 判断点是否在多边形内
         * @Title: IsPointInPoly
         * @param point 测试点
         * @param pts 多边形的点
         * @return
         * @return boolean
         * @throws
         */
        public static boolean isInPolygon(Point2D.Double point, List<Point2D.Double> pts){
    
            int N = pts.size();
            boolean boundOrVertex = true;
            int intersectCount = 0;//交叉点数量
            double precision = 2e-10; //浮点类型计算时候与0比较时候的容差
            Point2D.Double p1, p2;//临近顶点
            Point2D.Double p = point; //当前点
    
            p1 = pts.get(0);
            for(int i = 1; i <= N; ++i){
                if(p.equals(p1)){
                    return boundOrVertex;
                }
    
                p2 = pts.get(i % N);
                if(p.x < Math.min(p1.x, p2.x) || p.x > Math.max(p1.x, p2.x)){
                    p1 = p2;
                    continue;
                }
    
                //射线穿过算法
                if(p.x > Math.min(p1.x, p2.x) && p.x < Math.max(p1.x, p2.x)){
                    if(p.y <= Math.max(p1.y, p2.y)){
                        if(p1.x == p2.x && p.y >= Math.min(p1.y, p2.y)){
                            return boundOrVertex;
                        }
    
                        if(p1.y == p2.y){
                            if(p1.y == p.y){
                                return boundOrVertex;
                            }else{
                                ++intersectCount;
                            }
                        }else{
                            double xinters = (p.x - p1.x) * (p2.y - p1.y) / (p2.x - p1.x) + p1.y;
                            if(Math.abs(p.y - xinters) < precision){
                                return boundOrVertex;
                            }
    
                            if(p.y < xinters){
                                ++intersectCount;
                            }
                        }
                    }
                }else{
                    if(p.x == p2.x && p.y <= p2.y){
                        Point2D.Double p3 = pts.get((i+1) % N);
                        if(p.x >= Math.min(p1.x, p3.x) && p.x <= Math.max(p1.x, p3.x)){
                            ++intersectCount;
                        }else{
                            intersectCount += 2;
                        }
                    }
                }
                p1 = p2;
            }
            if(intersectCount % 2 == 0){//偶数在多边形外
                return false;
            } else { //奇数在多边形内
                return true;
            }
        }