1 using System;  2 using System.Collections.Generic;  3 using System.Linq;  4 using System.Text;  5 using ESRI.ArcGIS.Geometry;  6 using RGeos.Geometry  7   8 namespace RGeos.Geometry  9 { 10     public class CulmulateDistance 11     { 12         /// <summary> 13         /// 点到折线最短距离处距离折线起点的累积距离 14         /// </summary> 15         /// <param name="P">任意一点</param> 16         /// <param name="polyline">折线</param> 17         /// <returns></returns> 18         public static double CulmulateDist_Point_to_Polyline(IPoint P, IPolyline polyline) 19         { 20             ISegmentCollection segs = polyline as ISegmentCollection; 21             double min = double.MaxValue; 22             int segIndex = -1;//最短距离所在档的索引 23             for (int i = 0; i < segs.SegmentCount; i++) 24             { 25                 //点到每条线段的最短距离 26                 double dis = Dist_Point_to_Segment(P, segs.get_Segment(i)); 27                 if (dis < min) 28                 { 29                     min = dis; 30                     segIndex = i;//取出最小的一个 31                 } 32             } 33             double culmulateDis = 0; 34             for (int i = 0; i < segs.SegmentCount; i++) 35             { 36                 if (segIndex != i) 37                 { 38                     culmulateDis += segs.get_Segment(i).Length; 39                 } 40                 else 41                 { 42                     ISegment current = segs.get_Segment(i); 43                     Vector3d v = new Vector3d(); 44                     v.X = current.ToPoint.X - current.FromPoint.X; 45                     v.Y = current.ToPoint.Y - current.FromPoint.Y; 46  47                     Vector3d w = new Vector3d(); 48                     w.X = P.X - current.FromPoint.X; 49                     w.Y = P.Y - current.FromPoint.Y; 50  51                     double c1 = dot(w, v);//投影长度 52                     if (c1 <= 0)//这种情况最短距离在该线段的起点处 53                     { 54                         break; 55                     } 56                     double c2 = dot(v, v); 57                     if (c2 <= c1)//这种情况最短距离在该线段的终点处                       58                     { 59                         culmulateDis += Math.Sqrt(c2); 60                         break; 61                     } 62  63                     double b = c1 / c2; 64                     culmulateDis += Math.Sqrt(c1); 65                     IPoint Pb = new PointClass(); 66                     Pb.X = current.FromPoint.X + b * v.X; 67                     Pb.Y = current.FromPoint.Y + b * v.Y; 68                     break; 69                 } 70             } 71             return culmulateDis; 72         } 73  74         public static IPoint GetCentrePoint(IPolygon polygon) 75         { 76             IArea pArea = polygon as IArea; 77             IPoint pt = new PointClass(); 78             pt.X = pArea.Centroid.X; 79             pt.Y = pArea.Centroid.Y; 80             return pt; 81         } 82  83         public static double Dist_Point_to_Segment(IPoint P, ISegment S) 84         { 85             Vector3d v = new Vector3d(); 86             v.X = S.ToPoint.X - S.FromPoint.X; 87             v.Y = S.ToPoint.Y - S.FromPoint.Y; 88  89             Vector3d w = new Vector3d(); 90             w.X = P.X - S.FromPoint.X; 91             w.Y = P.Y - S.FromPoint.Y; 92  93             double c1 = dot(w, v); 94             if (c1 <= 0) 95                 return d(P, S.FromPoint); 96  97             double c2 = dot(v, v); 98             if (c2 <= c1) 99                 return d(P, S.ToPoint);100 101             double b = c1 / c2;102             IPoint Pb = new PointClass();103             Pb.X = S.FromPoint.X + b * v.X;104             Pb.Y = S.FromPoint.Y + b * v.Y;105             return d(P, Pb);106         }107         /// <summary>108         /// 向量的模109         /// </summary>110         /// <param name="v"></param>111         /// <returns></returns>112         public static double norm(Vector3d v)113         {114             return Math.Sqrt(dot2(v, v));  // norm = length of vector115         }116         /// <summary>117         /// 2D数量积，点乘118         /// </summary>119         /// <param name="u"></param>120         /// <param name="v"></param>121         /// <returns></returns>122         public static double dot2(Vector3d u, Vector3d v)123         {124             return ((u).X * (v).X + (u).Y * (v).Y);125         }126         public static double dot(Vector3d u, Vector3d v)127         {128             return ((u).X * (v).X + (u).Y * (v).Y + (u).Z * (v).Z);129         }130 131         public static double d(IPoint P, IPoint P1)132         {133             return Math.Sqrt((P1.X - P.X) * (P1.X - P.X) + (P1.Y - P.Y) * (P1.Y - P.Y));134         }135 136         /// <param name="x">增量X</param>137         /// <param name="y">增量Y</param>138         /// <returns>象限角</returns>139         public static double GetQuadrantAngle(double x, double y)140         {141             double theta = Math.Atan(y / x);142             if (x > 0 && y == 0) return 0;143             if (x == 0 && y > 0) return Math.PI / 2;144             if (x < 0 && y == 0) return Math.PI;145             if (x == 0 && y < 0) return 3 * Math.PI / 2;146 147             if (x > 0 && y > 0) return theta;148             if (x > 0 && y < 0) return Math.PI * 2 + theta;149             if (x < 0 && y > 0) return theta + Math.PI;150             if (x < 0 && y < 0) return theta + Math.PI;151             return theta;152         }153     }154 }