ArcEngine對面進行抽稀（減少節點數）

public class clsSimplyfyPolygon
{

    //對指定圖元，按指定buffer距離做抽稀
    public IPolygon doPolygonSimpled(IGeometry pGeometry, double dblDistance, int maxPointCount)
    {
        IPolygon pPolygon;
       
        ISegmentCollection pSegCol;
        IGeometryCollection pGeoCol;

        IPointCollection pntDoneCol = new MultipointClass();


        //  pGeometry = polygonFeature.Shape;
        pPolygon = (IPolygon)pGeometry;
        pSegCol = (ISegmentCollection)pPolygon;
        pGeoCol = (IGeometryCollection)pPolygon;

        for (int i = 0; i < pGeoCol.GeometryCount; i++)
        {
            IGeometry subGeometry;
            IPointCollection subPointCol;

            subGeometry = pGeoCol.get_Geometry(i);
            subPointCol = (IPointCollection)subGeometry;
            pntDoneCol.AddPointCollection(doSimpledPointCollection(ref subPointCol, dblDistance, maxPointCount));

        }
        return pPolygon;
    }
    //循環抽稀，ipointCollection
    public IPointCollection doSimpledPointCollection(ref IPointCollection pntCol, double dblDistance, int maxCount)
    {
        if (pntCol.PointCount > maxCount)
        {
            IPoint pntStart;
            IPoint pntMid;
            IPoint pntEnd;

            ArrayList arryDelIndexs = new ArrayList();
            arryDelIndexs.Clear();

            int modby3 = pntCol.PointCount % 3;
            int maxPointCount = pntCol.PointCount - modby3;

            for (int i = 0; i < maxPointCount; i = i + 3)
            {
                if ((i + 2) < pntCol.PointCount)
                {
                    pntStart = pntCol.get_Point(i);
                    pntMid = pntCol.get_Point(i + 1);
                    pntEnd = pntCol.get_Point(i + 2);

                    if (getMidDistanceFromThreePoints(pntStart, pntMid, pntEnd) < dblDistance)
                    {
                        arryDelIndexs.Add(i + 1);
                        //pntCol.RemovePoints(i + 1, 1);
                        //doSimpledPointCollection(ref pntCol, dblDistance, maxCount);
                    }
                }

            }

            if (arryDelIndexs.Count != 0)
            {
                for (int j = 0; j < arryDelIndexs.Count; j++)
                {

                    pntCol.RemovePoints(Convert.ToInt32(arryDelIndexs[j]) - j, 1);
                }
                doSimpledPointCollection(ref pntCol, dblDistance, maxCount);
            }

            if (pntCol.PointCount > maxCount)
            {
                doSimpledPointCollection(ref pntCol, dblDistance + dblDistance, maxCount);
            }
        }
        return pntCol;
    }

    //計算三點中，中間點到另外兩點的直線距離
    public double getMidDistanceFromThreePoints(IPoint pntStart, IPoint pntMid, IPoint pntEnd)
    {
        double A = pntStart.Y - pntEnd.Y;
        double B = pntEnd.X - pntStart.X;
        double C = pntStart.X * pntEnd.Y - pntEnd.X * pntStart.Y;
        double distance = Math.Abs(A * pntMid.X + B * pntMid.Y + C) / Math.Sqrt(A * A + B * B);
        return distance;


    }

}

}