topic Re : check if the point inside or outside the polyline in .NET Forum

check if the point inside or outside the polyline

Anonymous — Tue, 27 Jan 2015 07:24:51 GMT

Hi All

I need to check if the point inside or outside the polyline.

I know that many posts talked about this, but i did not found a real result till now.

Now i am trying with a peace of code that using TraceBoundary method, when user select a point inside an object, the boject color changed, the problem that i can not select the polylines only from other objects.

any help please, it very important for me.

Thanks

This my try.

Imports Autodesk.AutoCAD.ApplicationServices
Imports Autodesk.AutoCAD.DatabaseServices
Imports Autodesk.AutoCAD.EditorInput
Imports Autodesk.AutoCAD.Geometry
Imports Autodesk.AutoCAD.Runtime
Imports Autodesk.AutoCAD.Runtime.Interop
Imports Autodesk.AutoCAD.BoundaryRepresentation
Imports System.Collections.Generic
Imports System.Linq
Imports System.Text
Imports ErrorStatus = Autodesk.AutoCAD.Runtime.ErrorStatus
Imports acApp = Autodesk.AutoCAD.ApplicationServices.Application
Imports Autodesk.AutoCAD.ApplicationServices.DocumentExtension



<CommandMethod("TB")> _
        Public Sub TraceBoundary()

            Dim doc As Document = Application.DocumentManager.MdiActiveDocument
            Dim db As Database = doc.Database
            Dim ed As Editor = doc.Editor
            ' Select a seed point for our boundary
            Dim ppr As PromptPointResult = ed.GetPoint(vbLf & "Select internal point: ")

            If ppr.Status <> PromptStatus.OK Then
                Return
            End If
            ' Get the objects making up our boundary


            Dim objs As DBObjectCollection = ed.TraceBoundary(ppr.Value, True)
            If objs.Count > 0 Then
                Dim tr As Transaction = doc.TransactionManager.StartTransaction()
                Using tr
                    ' We'll add the objects to the model space
                    Dim bt As BlockTable = DirectCast(tr.GetObject(doc.Database.BlockTableId, OpenMode.ForRead), BlockTable)
                    Dim btr As BlockTableRecord = DirectCast(tr.GetObject(bt(BlockTableRecord.ModelSpace), OpenMode.ForWrite), BlockTableRecord)

                    ' Add our boundary objects to the drawing and

                    ' collect their ObjectIds for later use

                    Dim ids As New ObjectIdCollection()

                    For Each obj As DBObject In objs

                        'If TypeOf obj Is Polyline Then
                        '    MsgBox("Yes")
                        'End If
                        Dim ent As Entity = TryCast(obj, Entity)

                        If ent IsNot Nothing Then

                            ' Set our boundary objects to be of
                            ' our auto-incremented colour index
                            ent.ColorIndex = _index

                            ' Set the lineweight of our object
                            ent.LineWeight = LineWeight.LineWeight050

                            ' Add each boundary object to the modelspace
                            ' and add its ID to a collection
                            ids.Add(btr.AppendEntity(ent))
                            tr.AddNewlyCreatedDBObject(ent, True)

                        End If
                    Next
                    ' Increment our colour index
                    _index += 1
                    ' Commit the transaction
                    tr.Commit()

                End Using
            End If

        End Sub

Re: check if the point inside or outside the polyline

Anonymous — Tue, 27 Jan 2015 08:07:00 GMT

Hi,

Do you want to consider polylines only as boundary objects ? If the entities other than polylines are in different layers, switch off those layers first and then trace the boundary.

Regards,

gsktry

Re: check if the point inside or outside the polyline

Anonymous — Tue, 27 Jan 2015 08:57:59 GMT

Thank you gsktry

At the same time i need to get areas of polylines, if i consider polylines only as boundary objects, can i get the area also or no.

if the answer is yes, how to do this in code if you can please because i am new in this field.

Thank you very much

Re: check if the point inside or outside the polyline

Anonymous — Tue, 27 Jan 2015 10:16:24 GMT

I don't have any existing code. But my suggestion is here:

Your existing code creates the polyline and adds it to the model. So, you can get the area of the created polyline as shown below.

If TypeOf (ent) Is Polyline Then
	Dim pl As Polyline
	pl = DirectCast(ent, Polyline)
	If pl.Closed Then
	    MsgBox(pl.Area)
	End If
End If

Regards,

gsktry

Re: check if the point inside or outside the polyline

Anonymous — Tue, 27 Jan 2015 11:24:34 GMT

Here my function for detect if a blockreference is inside of a polyline :

    '***********************************************************************
    '**  procedure de détection si un point est dans une région(polyline) **
    '***********************************************************************
    '** ENTREE :                                                          **
    '**   - Ligne  : la polyline                                          **
    '**                Attention vérifier avant que la polyligne ne se    **
    '**                  croise pas elle-même (IsPolylineSelfIntercept)   **
    '**   - Bloc   : Le bloc a tester                                     **
    '** SORTIE :                                                          **
    '**   - True si dedans sinon false                                    **
    '***********************************************************************
    Public Function IsBlocInZoneFromPolyline(ByRef Bloc As BlockReference, ByRef Ligne As Polyline) As Boolean
        Dim OkRetour As Boolean = False
        '===========================================================================
        'Gestion des erreurs d'entrée :
        'Si pas définit
        If IsNothing(Bloc) = True Or IsNothing(Ligne) = True Then Return OkRetour
        'Si ligne non fermée
        If Ligne.Closed = False Then Return False
        '===========================================================================

        '===========================================================================
        'génération des points d'entrée de la fonction de calcul + vérification simple
        'du point de test
        Dim pt As New Point2d(Bloc.Position.X, Bloc.Position.Y)

        '  si le point est sur la polyligne
        Dim vn As Integer = Ligne.NumberOfVertices
        Dim colpt() As Point2d = Nothing
        ReDim colpt(vn)
        For i As Integer = 0 To vn - 1
            '// Could also get the 3D point here
            Dim pts As Point2d = Ligne.GetPoint2dAt(i)
            colpt(i) = New Point2d(pts.X, pts.Y)


            'Test si le point est sur un segment de la polyline si oui exit !
            Dim seg As Curve2d = Nothing
            Dim segType As SegmentType = Ligne.GetSegmentType(i)
            If (segType = SegmentType.Arc) Then
                seg = Ligne.GetArcSegment2dAt(i)
            ElseIf (segType = SegmentType.Line) Then
                seg = Ligne.GetLineSegment2dAt (i)
            End If
            If IsNothing(seg) = False Then
                OkRetour = seg.IsOn(pt)
                If OkRetour = True Then
                    Return True
                End If
            End If
        Next
        'ajout du point [0] pour finir la boucle !
        colpt(vn) = Ligne.GetPoint2dAt(0)

        '===========================================================================

        Dim RetFonction As Double
        RetFonction = wn_PnPoly(pt, colpt, vn)

        If RetFonction = 0 Then
            OkRetour = False
        Else
            OkRetour = True
        End If

        Return OkRetour
    End Function
    '**************************************************************************************
    '// Copyright 2000 softSurfer, 2012 Dan Sunday
    '// This code may be freely used and modified for any purpose
    '// providing that this copyright notice is included with it.
    '// SoftSurfer makes no warranty for this code, and cannot be held
    '// liable for any real or imagined damage resulting from its use.
    '// Users of this code must verify correctness for their application.
    '**************************************************************************************
    'isLeft(): tests if a point is Left|On|Right of an infinite line.
    '//    Input:  three points P0, P1, and P2
    '//    Return: >0 for P2 left of the line through P0 and P1
    '//            =0 for P2  on the line
    '//            <0 for P2  right of the line
    '//    See: Algorithm 1 "Area of Triangles and Polygons"
    Private Function isLeft(ByVal P0 As Point2d, ByVal P1 As Point2d, ByVal P2 As Point2d) As Double
        Return ((P1.X - P0.X) * (P2.Y - P0.Y) - (P2.X - P0.X) * (P1.Y - P0.Y))
    End Function
    '**************************************************************************************

    '**************************************************************************************
    '// wn_PnPoly(): winding number test for a point in a polygon
    '//      Input:   P = a point,
    '//               V[] = vertex points of a polygon V[n+1] with V[n]=V[0]
    '//      Return:  wn = the winding number (=0 only when P is outside)
    'int
    Private Function wn_PnPoly(ByVal P As Point2d, ByVal V() As Point2d, ByVal n As Double) As Double
        Dim wn As Double = 0    '// the  winding number counter
        '// loop through all edges of the polygon
        For i As Integer = 0 To n - 1
            'for (int i=0; i<n; i++) {   
            If (V(i).Y <= P.Y) Then                         '// edge from V[i] to  V[i+1]
                '// start y <= P.y
                If (V(i + 1).Y > P.Y) Then                  '// an upward crossing
                    If (isLeft(V(i), V(i + 1), P) > 0) Then  '// P left of  edge
                        wn = wn + 1                         '// have  a valid up intersect
                    End If
                End If

            Else                                            '// start y > P.y (no test needed)
                If (V(i + 1).Y <= P.Y) Then                 '// a downward crossing
                    If (isLeft(V(i), V(i + 1), P) < 0) Then  '// P right of  edge
                        wn = wn - 1                         '// have  a valid down intersect
                    End If
                End If
            End If
        Next
        Return wn
    End Function
    '**************************************************************************************

1 - Public Function IsBlocInZoneFromPolyline(ByRef Bloc As BlockReference, ByRef Ligne As Polyline) As Boolean

--> return true if the Pt of Block is inside of the Ligne

2 - Private Function wn_PnPoly(ByVal P As Point2d, ByVal V() As Point2d, ByVal n As Double) As Double

It is not my function but i have found in on the net.

3 -Private Function isLeft(ByVal P0 As Point2d, ByVal P1 As Point2d, ByVal P2 As Point2d) As Double

used in the wn_pnpoly

with this you can détect a point inside a poly or not.

Re: check if the point inside or outside the polyline

Anonymous — Wed, 28 Jan 2015 05:30:44 GMT

Hello gsktry

Thank you for help

I know how to get the area, my question was about how to deal with PL as boundary object.

Thank you again.

Re: check if the point inside or outside the polyline

Anonymous — Wed, 28 Jan 2015 05:35:00 GMT

Hello AubelecBE

I tried with your great code, but unfortunately it returns always false result.

i will send my code to see it

Thank you very much.

Re: check if the point inside or outside the polyline

Anonymous — Wed, 28 Jan 2015 05:38:05 GMT

Hello AubelecBE

This My try with your code.

<CommandMethod("xCatchArchAreas")> _
    Public Sub xCatchArchAreas()
        Dim myDB As Database = HostApplicationServices.WorkingDatabase

        Using myTrans As Transaction = myDB.TransactionManager.StartTransaction

            Dim myBlockTable As BlockTable = myDB.BlockTableId.GetObject(OpenMode.ForRead)
            Dim myModelSpace As BlockTableRecord = myBlockTable(BlockTableRecord.ModelSpace).GetObject(OpenMode.ForRead)

            For Each myObjectID As ObjectId In myModelSpace

                Dim myEntity As Entity = myObjectID.GetObject(OpenMode.ForRead)


                If TypeOf myEntity Is Polyline Then
                   
                    zzCatchArchAreas(myEntity)

                End If


            Next

            myTrans.Abort()

        End Using
    End Sub
    <CommandMethod("zzCatchArchAreas")> _
    Public Sub zzCatchArchAreas(pl As Polyline)
        Dim myDB As Database = HostApplicationServices.WorkingDatabase

        Using myTrans As Transaction = myDB.TransactionManager.StartTransaction

            Dim myBlockTable As BlockTable = myDB.BlockTableId.GetObject(OpenMode.ForRead)
            Dim myModelSpace As BlockTableRecord = myBlockTable(BlockTableRecord.ModelSpace).GetObject(OpenMode.ForRead)

            For Each myObjectID As ObjectId In myModelSpace

                Dim myEntity As Entity = myObjectID.GetObject(OpenMode.ForRead)

                Dim mybool As Boolean

                If TypeOf myEntity Is BlockReference Then

                    mybool = IsBlocInZoneFromPolyline(myEntity, pl)
                    MsgBox(mybool)
                End If


            Next

            myTrans.Abort()

        End Using


    End Sub


    Public Function IsBlocInZoneFromPolyline(ByRef Bloc As BlockReference, ByRef Ligne As Polyline) As Boolean
        Dim OkRetour As Boolean = False

        If IsNothing(Bloc) = True Or IsNothing(Ligne) = True Then Return OkRetour

        If Ligne.Closed = False Then Return False
        Dim pt As New Point2d(Bloc.Position.X, Bloc.Position.Y)


        Dim vn As Integer = Ligne.NumberOfVertices
        Dim colpt() As Point2d = Nothing
        ReDim colpt(vn)
        For i As Integer = 0 To vn - 1

            Dim pts As Point2d = Ligne.GetPoint2dAt(i)
            colpt(i) = New Point2d(pts.X, pts.Y)



            Dim seg As Curve2d = Nothing
            Dim segType As SegmentType = Ligne.GetSegmentType(i)
            If (segType = SegmentType.Arc) Then
                seg = Ligne.GetArcSegment2dAt(i)
            ElseIf (segType = SegmentType.Line) Then
                seg = Ligne.GetLineSegment2dAt(i)
            End If
            If IsNothing(seg) = False Then
                OkRetour = seg.IsOn(pt)
                If OkRetour = True Then
                    Return True
                End If
            End If
        Next

        colpt(vn) = Ligne.GetPoint2dAt(0)



        Dim RetFonction As Double
        RetFonction = wn_PnPoly(pt, colpt, vn)

        If RetFonction = 0 Then
            OkRetour = False
        Else
            OkRetour = True
        End If

        Return OkRetour
    End Function

    Private Function isLeft(ByVal P0 As Point2d, ByVal P1 As Point2d, ByVal P2 As Point2d) As Double
        Return ((P1.X - P0.X) * (P2.Y - P0.Y) - (P2.X - P0.X) * (P1.Y - P0.Y))
    End Function

    Private Function wn_PnPoly(ByVal P As Point2d, ByVal V() As Point2d, ByVal n As Double) As Double
        Dim wn As Double = 0

        For i As Integer = 0 To n - 1

            If (V(i).Y <= P.Y) Then

                If (V(i + 1).Y > P.Y) Then
                    If (isLeft(V(i), V(i + 1), P) > 0) Then
                        wn = wn + 1
                    End If
                End If

            Else
                If (V(i + 1).Y <= P.Y) Then
                    If (isLeft(V(i), V(i + 1), P) < 0) Then
                        wn = wn - 1
                    End If
                End If
            End If
        Next
        Return wn
    End Function

Re: check if the point inside or outside the polyline

Anonymous — Wed, 28 Jan 2015 11:50:17 GMT

Hi. i have copy past your code but i have del the second commandmethode

it is work for me on acad2015. i have tryed ucs and ucg. i have false and tru for the second.

here my file of test.

I dont use 3D only 2d. (architectural plan for my job. (electrical plan))

Re : check if the point inside or outside the polyline

_gile — Wed, 28 Jan 2015 20:18:28 GMT

Hi,

You can see this thread where two ways are provided to check if a point is inside a polyline: one using a MPolygon object which have a IsPointInsideMPolygon() method and another one (by Tony Tanzillo) using a Region and the BoundaryRepresentation (Brep) API. In both cases, it's easy to create a MPolygon or a Region from a closed Polyline.

Re: check if the point inside or outside the polyline

Anonymous — Thu, 29 Jan 2015 06:12:00 GMT

Hi AubelecBE,

I tried with your code again, it works good with your Block, it seems that there are something wrong in my Block.

Generally, i tried with MText and works good.

Thank you very much.

Re : check if the point inside or outside the polyline

Anonymous — Thu, 29 Jan 2015 06:14:19 GMT

Hi Gile,

Thank you for help, i will see it of course for more informations.