topic Re: Help get Point3d within boundary ? in .NET Forum

Help get Point3d within boundary ?

anhtrung — Thu, 30 Jul 2015 06:49:43 GMT

i have a boundary created, i have lots of Point3d but i want know how many Point3d within boundary it. Thank.

Re: Help get Point3d within boundary ?

SENL1362 — Thu, 30 Jul 2015 11:06:46 GMT

Simple 2D solution:

Extract the Boundary Point into this polyPoint collection, then test each pnt with Inside2D

There is also a solution from Tony which uses a Region to test inside or even crossing for entities.

       public static bool IsInside2D(Point3dCollection polyPoint, Point3d pnt)
        {
            if (polyPoint == null)
                return false;

            int i, j = polyPoint.Count - 1;
            bool inside2D = false;

            for (i = 0; i < polyPoint.Count; i++)
            {
                Point3d pi = polyPoint[i];
                Point3d pj = polyPoint[j];

                if ((pi.Y < pnt.Y && pj.Y >= pnt.Y || pj.Y < pnt.Y && pi.Y >= pnt.Y) &&
                    (pi.X <= pnt.X || pj.X <= pnt.X))
                    inside2D ^= (pi.X + (pnt.Y - pi.Y) / (pj.Y - pi.Y) * (pj.X - pi.X) < pnt.X);

                j = i;
            }
            return inside2D;
        }

Re: Help get Point3d within boundary ?

anhtrung — Thu, 30 Jul 2015 12:40:56 GMT

Thank SENL, but i want held boundary it. Only gets Point3D within Boundary.

Re: Help get Point3d within boundary ?

SENL1362 — Thu, 30 Jul 2015 13:45:55 GMT

        [CommandMethod( "TestInside", CommandFlags.NoPaperSpace)]
        public static void TestInside()
        {

            Document doc = Application.DocumentManager.MdiActiveDocument;
            if (doc == null)
               return;
            Database db = doc.Database;
            Editor ed = doc.Editor;

            try
            {
                PromptEntityResult per = ed.GetEntity("Select Polyline");
                if (per.Status != PromptStatus.OK)
                    return;
                var polyId = per.ObjectId;
                if (!Regex.IsMatch(polyId.ObjectClass.DxfName,"POLY",RegexOptions.IgnoreCase))
                    throw new System.Exception("Not a Polyline selected");

                Point3dCollection polyPnts = new Point3dCollection();
                using (Transaction tr=db.TransactionManager.StartTransaction())
                {
                    var poly = (Polyline)tr.GetObject(polyId, OpenMode.ForRead);
                    for (int i = 0; i < poly.NumberOfVertices; i++)
                        polyPnts.Add(poly.GetPoint3dAt(i));
                    tr.Commit();
                }
                ed.WriteMessage("\n PolyPnts: {0}", string.Join("; ", polyPnts.Cast<Point3d>()));

                while (true)
                {
                    PromptPointOptions askForPP = new PromptPointOptions("Select Point");
                    askForPP.AllowArbitraryInput = true;
                    PromptPointResult getPP = ed.GetPoint(askForPP);
                    //User escaped?
                    if (getPP.Status != PromptStatus.OK)
                        break;

                    Point3d ucsPP = getPP.Value;
                    Matrix3d ucsWcs = ed.CurrentUserCoordinateSystem;
                    Point3d pickedPointInWcs = ucsPP.TransformBy(ucsWcs);

                    var heIsIn = IsInside2D(polyPnts, pickedPointInWcs);
                    ed.WriteMessage("\n {0}:  ({1}) \n", heIsIn ? "IN" : "OUT", pickedPointInWcs.ToString());
                }
            }
            catch (System.Exception ex)
            {
                if (ed != null)
                    ed.WriteMessage("\n {0}", ex.Message);
            }
        }

        public static bool IsInside2D(Point3dCollection polyPoints, Point3d pnt)
        {
            if (polyPoints == null)
                return false;

            int i, j = polyPoints.Count - 1;
            bool inside2D = false;

            for (i = 0; i < polyPoints.Count; i++)
            {
                Point3d pi = polyPoints[i];
                Point3d pj = polyPoints[j];

                if ((pi.Y < pnt.Y && pj.Y >= pnt.Y || pj.Y < pnt.Y && pi.Y >= pnt.Y) &&
                    (pi.X <= pnt.X || pj.X <= pnt.X))
                    inside2D ^= (pi.X + (pnt.Y - pi.Y) / (pj.Y - pi.Y) * (pj.X - pi.X) < pnt.X);

                j = i;
            }
            return inside2D;
        }

Re: Help get Point3d within boundary ?

anhtrung — Thu, 30 Jul 2015 13:46:09 GMT

Thank SENL. i can do it.