GIS算法-点是否在多边形内

射线法与转角法

代码

//点在多边形内 射线法
        public static bool IsPointInPolygonRadial(Vertex vertexP, Polygon polygon)
           {
               bool pResult = false;
             

               int pCountInOut = 0;

                //射线
               Point pt= new Point(100000,vertexP.CenterPoint.Y);
               ShapeCollection pTempShapeCol = new ShapeCollection(new Shape[] {vertexP,new Vertex(pt)});
               Segment pRadialY = new Segment(pTempShapeCol);

               

                //多边形所有边
               List<AlgorithmDataStructure.Segment> pSegmentsOfPolygon = AlgorithmDataStructure.ShapeUtility.GetSegmentsOfPolygon(polygon);

               for (int i = 0; i < pSegmentsOfPolygon.Count; i++)
               {
                   
                       //水平边不参与相交测试
                       if (AlgorithmDataStructure.ShapeUtility.IsSegmentHorizontal(pSegmentsOfPolygon[i]))
                       {
                           
                           continue;
                       }
                       //交点存在
                       Vertex pIntersectVertexRadialWithSegment = IsSegmentsIntersectWithPolynomial(pRadialY, pSegmentsOfPolygon[i]);
                       if (pIntersectVertexRadialWithSegment != null)
                       {
                           //射线与边的交点控制在边P点右边
                           if (vertexP.CenterPoint.X < pIntersectVertexRadialWithSegment.CenterPoint.X && vertexP.CenterPoint.Y == pIntersectVertexRadialWithSegment.CenterPoint.Y)
                           {
                               //方向向上的边
                               if (AlgorithmDataStructure.ShapeUtility.IsSegmentUpward(pSegmentsOfPolygon[i]))
                               {
                                   //交点不能与终点相同
                                   if (pIntersectVertexRadialWithSegment.CenterPoint.X != pSegmentsOfPolygon[i].Vertex2.CenterPoint.X
                                       || pIntersectVertexRadialWithSegment.CenterPoint.Y != pSegmentsOfPolygon[i].Vertex2.CenterPoint.Y)
                                   {
                                       pCountInOut++;
                                   }
                               }

                               //方向向下的边
                               if (AlgorithmDataStructure.ShapeUtility.IsSegmentDownward(pSegmentsOfPolygon[i]))
                               {
                                   //交点不能与起点相同
                                   if (pIntersectVertexRadialWithSegment.CenterPoint.X != pSegmentsOfPolygon[i].Vertex1.CenterPoint.X
                                       || pIntersectVertexRadialWithSegment.CenterPoint.Y != pSegmentsOfPolygon[i].Vertex1.CenterPoint.Y)
                                   {
                                       pCountInOut++;
                                   }
                               }
                           }
                           
                       }

               }

               if ((pCountInOut == 1) || (pCountInOut % 2 != 0))
               {
                   pResult = true; 
               }

               return pResult;
           }

 

代码

 //点在多边形内 转角法
        public static bool IsPointInPolygonAngle(Vertex vertexP, Polygon polygon)
        {
            bool pResult = false;


            int pCountWN = 0;

            //射线
            Point pt = new Point(100000, vertexP.CenterPoint.Y);
            ShapeCollection pTempShapeCol = new ShapeCollection(new Shape[] { vertexP, new Vertex(pt) });
            Segment pRadialY = new Segment(pTempShapeCol);



            //多边形所有边
            List<AlgorithmDataStructure.Segment> pSegmentsOfPolygon = AlgorithmDataStructure.ShapeUtility.GetSegmentsOfPolygon(polygon);

            for (int i = 0; i < pSegmentsOfPolygon.Count; i++)
            {

                //水平边不参与相交测试
                if (AlgorithmDataStructure.ShapeUtility.IsSegmentHorizontal(pSegmentsOfPolygon[i]))
                {

                    continue;
                }
                if (ShapeUtility.IsSegmentUpward(pSegmentsOfPolygon[i]))
                {
                    //P点严格在边的左边，矢量(v1,v2)前进方向左边
                    if (ShapeUtility.IsPointAtSegmentLeftSide(vertexP, pSegmentsOfPolygon[i]))
                    {
                        Vertex pIntersectVertexRadialWithSegment = IsSegmentsIntersectWithPolynomial(pRadialY, pSegmentsOfPolygon[i]);
                        if (pIntersectVertexRadialWithSegment != null)
                        {
                            //射线与边的交点控制在P点右边
                            if (vertexP.CenterPoint.X < pIntersectVertexRadialWithSegment.CenterPoint.X && vertexP.CenterPoint.Y == pIntersectVertexRadialWithSegment.CenterPoint.Y)
                            {
                                //交点不能与终点相同
                                if (pIntersectVertexRadialWithSegment.CenterPoint.X != pSegmentsOfPolygon[i].Vertex2.CenterPoint.X
                                    || pIntersectVertexRadialWithSegment.CenterPoint.Y != pSegmentsOfPolygon[i].Vertex2.CenterPoint.Y)
                                {

                                    pCountWN++;
                                }
                            }
                        }
                    }
                }
                else if (ShapeUtility.IsSegmentDownward(pSegmentsOfPolygon[i]))
                {
                    //P点严格在边的左边，矢量(v1,v2)前进方向左边
                    if (ShapeUtility.IsPointAtSegmentRightSide(vertexP, pSegmentsOfPolygon[i]))
                    {
                        Vertex pIntersectVertexRadialWithSegment = IsSegmentsIntersectWithPolynomial(pRadialY, pSegmentsOfPolygon[i]);
                        if (pIntersectVertexRadialWithSegment != null)
                        {
                            //射线与边的交点控制在P点右边
                            if (vertexP.CenterPoint.X < pIntersectVertexRadialWithSegment.CenterPoint.X && vertexP.CenterPoint.Y == pIntersectVertexRadialWithSegment.CenterPoint.Y)
                            {
                                //交点不能与终点相同
                                if (pIntersectVertexRadialWithSegment.CenterPoint.X != pSegmentsOfPolygon[i].Vertex2.CenterPoint.X
                                    || pIntersectVertexRadialWithSegment.CenterPoint.Y != pSegmentsOfPolygon[i].Vertex2.CenterPoint.Y)
                                {

                                    pCountWN--;
                                }
                            }
                        }
                    }
                }

              
            }

            if (pCountWN!=0)
            {
                pResult = true;
            }

            return pResult;
        }

 

 

转载于:https://www.cnblogs.com/LuGang/archive/2010/06/02/1749966.html