private void button1_Click(object sender, EventArgs e) { //var result = intersect3(point1, point2, point3, point4); var strPoints = this.txtPoints.Text.Trim(); //数据库复制出来的经纬度字符串 strPoints = strPoints.Substring(0, strPoints.Length - 1); var pointArr = strPoints.Split(';'); var lineList = new List<MapLine>(); for (int i = 0; i < pointArr.Length; i++) { //y 经度 //x 纬度 var line = new MapLine(); string[] tempPoint1 = pointArr[i].Split(','); line.Point1 = new MapPoint() {y = Convert.ToDouble(tempPoint1[0]), x = Convert.ToDouble(tempPoint1[1])}; string[] tempPoint2; if (i == pointArr.Length - 1) { tempPoint2 = pointArr[0].Split(','); } else { tempPoint2 = pointArr[i + 1].Split(','); } line.Point2 = new MapPoint() {y = Convert.ToDouble(tempPoint2[0]), x = Convert.ToDouble(tempPoint2[1])}; lineList.Add(line); } bool xj = false; for (var i = 0; i < lineList.Count; i++) { var count = 0; for (var j = 0; j < lineList.Count; j++) { if (i == j)//如果等于自己,不比较 continue; var result = intersect(lineList[i].Point1, lineList[i].Point2, lineList[j].Point1, lineList[j].Point2); if (result) { count++; } } if (count > 2) { xj = true; } } MessageBox.Show(xj ? "相交" : "不相交"); } //叉积 double mult(MapPoint a, MapPoint b, MapPoint c) { return (a.x - c.x) * (b.y - c.y) - (b.x - c.x) * (a.y - c.y); } //aa, bb为一条线段两端点 cc, dd为另一条线段的两端点 相交返回true, 不相交返回false bool intersect(MapPoint aa, MapPoint bb, MapPoint cc, MapPoint dd) { if (Math.Max(aa.x, bb.x) < Math.Min(cc.x, dd.x)) { return false; } if (Math.Max(aa.y, bb.y) < Math.Min(cc.y, dd.y)) { return false; } if (Math.Max(cc.x, dd.x) < Math.Min(aa.x, bb.x)) { return false; } if (Math.Max(cc.y, dd.y) < Math.Min(aa.y, bb.y)) { return false; } if (mult(cc, bb, aa) * mult(bb, dd, aa) < 0) { return false; } if (mult(aa, dd, cc) * mult(dd, bb, cc) < 0) { return false; } return true; }
strPoints
例如 106.549238056551,29.5682761629536;106.544257083204,29.5651964736277;106.550028675985,29.5651166254344;106.544602513089,29.5681623774632;