Alignment–Finding Direction at Point

The code snippet below shows how to find the tangent direction on an alignment at a given statin/offset value. This may be useful in performing report calculations. In looking through the API documentation it may not be easily noticed since it’s hiding in the PointLocationEx method of an alignment.

        Dim settingsStation As AeccLandLib.AeccSettingsStation
        settingsStation = ReportApplication.AeccXDatabase.Settings.AlignmentSettings.AmbientSettings.StationSettings
        Dim tolerance As Double
        tolerance = Math.Pow(10, -settingsStation.Precision.Value)

        Dim curStation As Double
        For curStation = stationStart To stationEnd Step staIncment
            Dim curNorthing As Double
            Dim curEasting As Double
            Dim curTangent As Double

            Try
                If oAlignment.PointLocationEx(curStation, 0.0, tolerance, curEasting, curNorthing, curTangent) _
            = AeccLandLib.AeccAlignmentReturnValue.aeccOK Then
                    Dim stationString As String
                    stationString = oAlignment.GetStationStringWithEquations(curStation)

                    Dim alignData As New DirectionData
                    alignData.station = stationString
                    alignData.northing = FormatCoordSettings(curNorthing)
                    alignData.easting = FormatCoordSettings(curEasting)
                    alignData.tangentialDirection = FormatDirSettings(Math.PI / 2 - curTangent)

                    m_AlignDataList.Add(alignData)
                End If
            Catch ex As Exception
                Diagnostics.Debug.Assert(False, ex.Message)
            End Try
        Next

The code snippet is from the Civil 3D Reports Source code that ships with the product.