Traversing Geometric network

Question

Hello guys and gals

I am trying to traverse geometric network and getting a single property out of every feature on the way. My starting point is certain IFeature which i cast into ISimpleJunctionFeature and use it in IForwardStarGEN.FindAdjacent which  provides me only with number of adjacent elements. I then use IForwardStarGEN.QueryAdjacentEdge etc. and i get

which in turn getse me IFeature, the property i needed class id etc. But how can i continue the path down the geometric network? I assume i need a recursion, but I seem to be stuck and there seems to be no examples on the web whatsoever, plus the documentation is a bit shoddy.

Thank you for any hints

Best regards,

Matej

MatejSkerjanc · Answer

Thank you again, once im back to project regarding traversing I'll use this excerpt.

Hornbydd · Answer

Matej, I can go one better, here is some old VBA code I had developed to create a route between 2 points on a river network. This will certainly help you in understand the steps as it's not immediately obvious what the sequence is! Some of it may not be relevant to you as this function is trying to return a polyline. Public Function Generate_route_between_2_points(theStartPoint As IPoint, theEndpoint As IPoint) As ICurve '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Description: ' ' This public function attempts to calculate the route along the network between ' ' the 2 points supplied to it. If it fails (due to snap tolerance) then a NULL ' ' geometry is returned. It returns a geometry of type ICurve. ' ' ' ' Updated on 14/5/2003 ' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' Show_message_in_StatusBar "Tracing network..." ''''''''''''''''''''''''' ' Define an empty curve ' ''''''''''''''''''''''''' Dim anEmptyCurve As ICurve Set anEmptyCurve = Nothing '''''''''''''''''''''''''''''' ' Get handle on featureclass ' '''''''''''''''''''''''''''''' Dim pMXDocument As IMxDocument Set pMXDocument = ThisDocument Dim pmap As IMap Set pmap = pMXDocument.FocusMap Dim pLayer As ILayer Dim pFeatureLayer As IFeatureLayer Set pFeatureLayer = FindLayer("Rivers") ''''''''''''''''''''''''' ' Get handle on network ' ''''''''''''''''''''''''' Dim pFeatureClass As IFeatureClass Set pFeatureClass = pFeatureLayer.FeatureClass Dim pFeatureDataset As IFeatureDataset Set pFeatureDataset = pFeatureClass.FeatureDataset Dim pNetworkCollection As INetworkCollection Set pNetworkCollection = pFeatureDataset Dim pGeometricNetWork As IGeometricNetwork Set pGeometricNetWork = pNetworkCollection.GeometricNetwork(0) Dim pNetwork As INetwork Set pNetwork = pGeometricNetWork.Network ''''''''''''''''''''''''''''''''''' ' Test to see if network is Valid ' ''''''''''''''''''''''''''''''''''' If pNetwork.status <> esriNSValidNetwork Then MsgBox "Network is not valid! Bailing out now to stop system crash.", vbCritical, "Fatal Error!" End End If ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Point to EID - Find nearest edge to point within 100 map units. Note that the ' ' returned point "theFirstLocation" is used later for identifying the sub curve ' ' of the traced route. ' ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' Dim pPointToEID As IPointToEID Set pPointToEID = New PointToEID Dim nearestEdgeEID As Long Dim theFirstLocation As IPoint Dim aPercentage As Double With pPointToEID .SnapTolerance = 100 Set .SourceMap = pmap Set .GeometricNetwork = pGeometricNetWork .GetNearestEdge theStartPoint, nearestEdgeEID, theFirstLocation, aPercentage End With '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Check to see if theStartPoint selected an edge feature, if not return a NULL shape ' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' If theFirstLocation Is Nothing Then Set Generate_route_between_2_points = anEmptyCurve Exit Function End If ' ' Convert the EID to a feature class ID, feature ID, and sub ID ' Dim lFCID As Long, lFID As Long, lSubID As Long Dim pNetElements As INetElements Set pNetElements = pNetwork pNetElements.QueryIDs nearestEdgeEID, esriETEdge, lFCID, lFID, lSubID ' ' Now create the flag that will be used by the tracesolver ' Dim pNetFlag As INetFlag Set pNetFlag = New EdgeFlag With pNetFlag .UserClassID = lFCID .UserID = lFID .UserSubID = lSubID End With ' ' Now do it all again with the second point! ' Set pPointToEID = New PointToEID Dim theSecondLocation As IPoint With pPointToEID .SnapTolerance = 100 Set .SourceMap = pmap Set .GeometricNetwork = pGeometricNetWork .GetNearestEdge theEndpoint, nearestEdgeEID, theSecondLocation, aPercentage End With '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Check to see if theEndPoint selected an edge feature, if not return a NULL shape ' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' If theSecondLocation Is Nothing Then Set Generate_route_between_2_points = anEmptyCurve Exit Function End If Set pNetElements = pNetwork pNetElements.QueryIDs nearestEdgeEID, esriETEdge, lFCID, lFID, lSubID Dim anotherpNetFlag As INetFlag Set anotherpNetFlag = New EdgeFlag With anotherpNetFlag .UserClassID = lFCID .UserID = lFID .UserSubID = lSubID End With '''''''''''''''''''''''''''''''''''''''' ' Establish a trace flow solver object ' '''''''''''''''''''''''''''''''''''''''' Dim pTraceFlowSolver As ITraceFlowSolver Set pTraceFlowSolver = New TraceFlowSolver Dim pNetSolver As INetSolver Set pNetSolver = pTraceFlowSolver Set pNetSolver.SourceNetwork = pNetwork '''''''''''''''''''''''''''''' ' Ensure solver uses weights ' '''''''''''''''''''''''''''''' Dim pNetSolverWeights As INetSolverWeights Set pNetSolverWeights = pTraceFlowSolver Dim pNetWeight As INetWeight Dim pNetSchema As INetSchema Set pNetSchema = pNetwork Set pNetWeight = pNetSchema.WeightByName("Length_Weight") Set pNetSolverWeights.FromToEdgeWeight = pNetWeight Set pNetSolverWeights.ToFromEdgeWeight = pNetWeight ''''''''''''''''''''''''''''''''''' ' Load trace solver with netflags ' ''''''''''''''''''''''''''''''''''' Dim arrayOfEdgeFlags(2) As IEdgeFlag Set arrayOfEdgeFlags(0) = pNetFlag Set arrayOfEdgeFlags(1) = anotherpNetFlag pTraceFlowSolver.PutEdgeOrigins 2, arrayOfEdgeFlags(0) ''''''''''''' ' Run trace ' ''''''''''''' Dim pEnumJuncIDs As IEnumNetEID Dim pEnumEdgeIDs As IEnumNetEID Dim pSegs(1) As Variant pTraceFlowSolver.FindPath esriFMConnected, esriSPObjFnMinSum, pEnumJuncIDs, pEnumEdgeIDs, 1, pSegs(0) ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' In ArcView a path could be created without any cost, ie a zero length path. Not ' ' sure if ArcMap does the same thing so test here to see if the generated path ' ' actually has an associated cost (more than 0 segments). If it does not, return ' ' a NULL ICurve. ' ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' If pSegs(0) < 1 Then Set Generate_route_between_2_points = anEmptyCurve Exit Function End If ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' FindPath has returned the enumerate pEnumEdgeIDs which we will now use to get the ' ' features and build a long polyline ' ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' Dim pEIDInfo As IEIDInfo Dim pEnumEIDInfo As IEnumEIDInfo Dim pEIDHelper As IEIDHelper '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Create a new object of EIDHelper and set some propertise ' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' Set pEIDHelper = New EIDHelper Set pEIDHelper.GeometricNetwork = pGeometricNetWork Set pEIDHelper.OutputSpatialReference = Nothing pEIDHelper.ReturnFeatures = True '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Now create an enumerate object from EIDHelper and make sure it's reset ' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' Set pEnumEIDInfo = pEIDHelper.CreateEnumEIDInfo(pEnumEdgeIDs) pEnumEIDInfo.Reset '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Loop through pEnumEIDInfo getting the features of the individual elements ' ' that make up the route and union them into a single geometry (polyline). ' ' This section of code was updated on 14/5/2003 to improve speed of ' ' constructing polyline from trace on network. Previous code used to loop ' ' throught each network element merging them together one by one, we now use ' ' the more efficient GeometryBag and topological operator constructUnion. ' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' Dim pGeometryCollection As IGeometryCollection Set pGeometryCollection = New GeometryBag Dim pTopologicalOperator As ITopologicalOperator Dim pFeature As IFeature Dim pGeometry As IGeometry ''''''''''''''''''''''''''''''''''''''''''''''''''' ' Now loop through adding them to the geometrybag ' ' via it's interface of geometry collection. ' ''''''''''''''''''''''''''''''''''''''''''''''''''' Show_message_in_StatusBar "Turning trace into polyline..." For aCounter = 1 To pEnumEIDInfo.count Set pEIDInfo = pEnumEIDInfo.Next Set pFeature = pEIDInfo.Feature Set pGeometry = pFeature.ShapeCopy pGeometryCollection.AddGeometry pGeometry Next aCounter ''''''''''''''''''''''''''''''''''''''''''''''' ' Having add the geometries to the collection ' ' we now union them into a single polyline. ' ''''''''''''''''''''''''''''''''''''''''''''''' Set pTopologicalOperator = New Polyline pTopologicalOperator.ConstructUnion pGeometryCollection ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' This new line is constructed from all the edges that it traced along, this includes ' ' the full length of the edge that the flag was on. We do not want this, we want the ' ' distance travelled between the 2 points ' ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' Dim pCurve As ICurve Dim pNewCurve As ICurve Dim aDummyPoint As IPoint Dim bRight As Boolean Dim distanceAlongCurve As Double Dim distanceFromCurve As Double Dim FirstPointAlong As Double Dim SecondPointAlong As Double Set pCurve = pTopologicalOperator ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Query curve to find distance along curve for theFirstLocation, unfortunately also ' ' need to supply other variables as these are required ' ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' pCurve.QueryPointAndDistance esriNoExtension, theFirstLocation, False, aDummyPoint, distanceAlongCurve, distanceFromCurve, bRight FirstPointAlong = distanceAlongCurve '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Query curve to find distance along curve for theSecondLocation, unfortunately also ' ' need to supply other variables as these are required ' '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' pCurve.QueryPointAndDistance esriNoExtension, theSecondLocation, False, aDummyPoint, distanceAlongCurve, distanceFromCurve, bRight SecondPointAlong = distanceAlongCurve ''''''''''''''''''''''' ' Construct sub curve ' ''''''''''''''''''''''' pCurve.GetSubcurve FirstPointAlong, SecondPointAlong, False, pNewCurve ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' ' Test if the final curve has any length, just to be on the safe side.... ' ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' If pNewCurve.Length > 0 Then Set Generate_route_between_2_points = pNewCurve Else Set Generate_route_between_2_points = anEmptyCurve End If End Function‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍‍

MatejSkerjanc · Answer

Sounds like I've missed a step or two, thank you for nudging me to the right direction.

best regards,

Matej