' This allows you to select a planar face.
'
' The program will then find the longest LINEAR edge of that face.
' It will find the start and end points of that edge.
'
' Then it will find the LINEAR edge of the face that intersects
' the longest edge at the start point of the long edge.
'
' It creates vectors based on those two edges, and then creates
' a matrix from those vectors.
'
' It creates a CSYS entity whose origin is at the start point of
' the long edge, and which is aligned to the matrix.
'
' Then it moves the WCS to the newly-created CSYS.
'
' There is very little error-checking, so it may not behave nicely if
' one of the expected prerequisites mentioned above is not met.
'
' Also, you might want to modify it to allow the user to 
' reverse the X-vector and put the origin at the other end
' of the longest edge, because it is hard-coded to use the start
' point of that edge, which will sometimes be wrong.

Option Strict Off

Imports System
Imports NXOpen
Imports NXOpen.UF
Imports NXOpen.UI
Imports NXOpen.Utilities

Module wcs_from_face_and_longest_edge

    Dim s As Session = Session.GetSession()
    Dim ufs As UFSession = UFSession.GetUFSession()
    Dim lw As ListingWindow = s.ListingWindow

    Sub Main()

        Dim planarFace As NXOpen.Tag = NXOpen.Tag.Null
        Dim longEdge As NXOpen.Tag = NXOpen.Tag.Null
        Dim otherEdge As NXOpen.Tag = NXOpen.Tag.Null
        Dim origin() As Double = {0, 0, 0}

        Dim xVector(2) As Double
        Dim yVector(2) As Double

        If select_a_planar_face(planarFace) = Selection.Response.Ok Then

            ufs.Disp.SetHighlight(planarFace, 0)

        End If

        Dim faceObject As Face = NXObjectManager.Get(planarFace)
        Dim edges() As Edge = faceObject.GetEdges()

        longEdge = get_longest_edge(edges)

        Dim sp(2) As Double
        Dim ep(2) As Double
        Dim lineData As UFCurve.Line
        lineData.start_point = sp
        lineData.end_point = ep

        ufs.Curve.AskLineData(longEdge, lineData)
        sp = lineData.start_point
        ep = lineData.end_point

        ufs.Vec3.Sub(ep, sp, xVector)
        ufs.Vec3.Copy(sp, origin)

        Dim sp2(2) As Double
        Dim ep2(2) As Double

        otherEdge = find_edge_adjacent_to_start_point(edges, sp, longEdge)

        ufs.Curve.AskLineData(otherEdge, lineData)
        sp2 = lineData.start_point
        ep2 = lineData.end_point

        If sp2(0) = sp(0) And sp2(1) = sp(1) And sp2(2) = sp(2) Then
            ufs.Vec3.Sub(ep2, sp2, yVector)
        Else
            ufs.Vec3.Sub(sp2, ep2, yVector)
        End If
        Dim mtx As NXOpen.Tag = NXOpen.Tag.Null
        Dim new_csys As NXOpen.Tag = NXOpen.Tag.Null
        Dim mtx_vals(8) As Double
        ufs.Mtx3.Initialize(xVector, yVector, mtx_vals)

        ufs.Csys.CreateMatrix(mtx_vals, mtx)
        ufs.Csys.CreateCsys(origin, mtx, new_csys)

        If new_csys <> NXOpen.Tag.Null Then
            ufs.Csys.SetWcs(new_csys)
        End If

    End Sub

    Function find_edge_adjacent_to_start_point(ByVal edges() As Edge, _
             ByVal org() As Double, ByVal longEdge As NXOpen.Tag) As NXOpen.Tag

        Dim thisEdge As NXOpen.Tag = NXOpen.Tag.Null
        Dim inx As Integer = 0

        For inx = 0 To edges.GetUpperBound(0)
            thisEdge = edges(inx).Tag

            If thisEdge <> longEdge Then ' to make sure we skip the xVector edge
                Dim edgeType As Integer = 0
                ufs.Modl.AskEdgeType(thisEdge, edgeType)
                If edgeType = UFConstants.UF_MODL_LINEAR_EDGE Then

                    Dim sp(2) As Double
                    Dim ep(2) As Double
                    Dim lineData As UFCurve.Line
                    lineData.start_point = sp
                    lineData.end_point = ep

                    ufs.Curve.AskLineData(thisEdge, lineData)
                    sp = lineData.start_point
                    ep = lineData.end_point

                    If sp(0) = org(0) And sp(1) = org(1) And sp(2) = org(2) Then
                        Return thisEdge
                    End If

                    If ep(0) = org(0) And ep(1) = org(1) And ep(2) = org(2) Then
                        Return thisEdge
                    End If
                End If

            End If
        Next

    End Function

    Function get_longest_edge(ByVal edges() As Edge) As NXOpen.Tag
        Dim lgth As Double = 0
        Dim inx As Integer = 0
        Dim thisEdge As NXOpen.Tag = NXOpen.Tag.Null
        Dim longestNumber As Double = 0
        Dim longestEdge As NXOpen.Tag = NXOpen.Tag.Null

        For inx = 0 To edges.GetUpperBound(0)

            thisEdge = edges(inx).Tag
            Dim edgeType As Integer = 0
            ufs.Modl.AskEdgeType(thisEdge, edgeType)

            If edgeType = UFConstants.UF_MODL_LINEAR_EDGE Then

                ufs.Curve.AskArcLength(thisEdge, 0, 1, ModlUnits.ModlUnitsPart, lgth)

                If lgth > longestNumber Then
                    longestEdge = thisEdge
                    longestNumber = lgth
                End If

            End If

        Next inx

        Return longestEdge

    End Function

    Function select_a_planar_face(ByRef face As NXOpen.Tag) As Selection.Response

        Dim message As String = "Planar Face:"
        Dim title As String = "Select a PLANAR FACE"
        Dim scope As Integer = UFConstants.UF_UI_SEL_SCOPE_ANY_IN_ASSEMBLY
        Dim response As Integer
        Dim view As NXOpen.Tag
        Dim cursor(2) As Double
        Dim mask_face As UFUi.SelInitFnT = AddressOf mask_for_planar_faces

        ufs.Ui.LockUgAccess(UFConstants.UF_UI_FROM_CUSTOM)

        Try
            ufs.Ui.SelectWithSingleDialog(message, title, scope, mask_face, _
                         Nothing, response, face, cursor, view)
        Finally
            ufs.Ui.UnlockUgAccess(UFConstants.UF_UI_FROM_CUSTOM)
        End Try

        If response <> UFConstants.UF_UI_OBJECT_SELECTED And _
           response <> UFConstants.UF_UI_OBJECT_SELECTED_BY_NAME Then
            Return Selection.Response.Cancel
        Else
            Return Selection.Response.Ok
        End If

    End Function

    Function mask_for_planar_faces(ByVal select_ As IntPtr, _
                           ByVal userdata As IntPtr) As Integer

        Dim num_triples As Integer = 1
        Dim mask_triples(0) As UFUi.Mask
        mask_triples(0).object_type = UFConstants.UF_solid_type
        mask_triples(0).object_subtype = UFConstants.UF_solid_face_subtype
        mask_triples(0).solid_type = UFConstants.UF_UI_SEL_FEATURE_PLANAR_FACE

        ufs.Ui.SetSelMask(select_, _
                           UFUi.SelMaskAction.SelMaskClearAndEnableSpecific, _
                           num_triples, mask_triples)
        Return UFConstants.UF_UI_SEL_SUCCESS

    End Function


    Public Function GetUnloadOption(ByVal dummy As String) As Integer

        Return Session.LibraryUnloadOption.Immediately

    End Function

End Module