Reference Intersector Class

public class RayProjection : IExternalCommand
{
    public Result Execute(ExternalCommandData revit, ref string message, ElementSet elements)
    {
        Document doc = revit.Application.ActiveUIDocument.Document;

        ICollection<ElementId> selectedIds = revit.Application.ActiveUIDocument.Selection.GetElementIds();

        // If skylight is selected, process it.
        FamilyInstance skylight = null;
        if (selectedIds.Count == 1)
        {
            foreach (ElementId id in selectedIds)
            {
                Element e = doc.GetElement(id);
                if (e is FamilyInstance)
                {
                    FamilyInstance instance = e as FamilyInstance;
                    bool isWindow = (instance.Category.BuiltInCategory == BuiltInCategory.OST_Windows);
                    bool isHostedByRoof = (instance.Host.Category.BuiltInCategory == BuiltInCategory.OST_Roofs);

                    if (isWindow && isHostedByRoof)
                    {
                        skylight = instance;
                    }
                }
            }
        }

        if (skylight == null)
        {
            message = "Please select one skylight.";
            return Result.Cancelled;
        }

        // Calculate the height
        Line line = CalculateLineAboveFloor(doc, skylight);

        // Create a model curve to show the distance
        Plane plane = Plane.CreateByNormalAndOrigin(new XYZ(1, 0, 0), line.GetEndPoint(0));
        SketchPlane sketchPlane = SketchPlane.Create(doc, plane);

        ModelCurve curve = doc.Create.NewModelCurve(line, sketchPlane);

        // Show a message with the length value
        TaskDialog.Show("Distance", "Distance to floor: " + String.Format("{0:f2}", line.Length));

        return Result.Succeeded;
    }

    /// <summary>
    /// Determines the line segment that connects the skylight to the nearest floor.
    /// </summary>
    /// <returns>The line segment.</returns>
    private Line CalculateLineAboveFloor(Document doc, FamilyInstance skylight)
    {
        // Find a 3D view to use for the ReferenceIntersector constructor
        FilteredElementCollector collector = new FilteredElementCollector(doc);
        Func<View3D, bool> isNotTemplate = v3 => !(v3.IsTemplate);
        View3D view3D = collector.OfClass(typeof(View3D)).Cast<View3D>().First<View3D>(isNotTemplate);

        // Use the center of the skylight bounding box as the start point.
        BoundingBoxXYZ box = skylight.get_BoundingBox(view3D);
        XYZ center = box.Min.Add(box.Max).Multiply(0.5);

        // Project in the negative Z direction down to the floor.
        XYZ rayDirection = new XYZ(0, 0, -1);

        ElementClassFilter filter = new ElementClassFilter(typeof(Floor));

        ReferenceIntersector refIntersector = new ReferenceIntersector(filter, FindReferenceTarget.Face, view3D);
        ReferenceWithContext referenceWithContext = refIntersector.FindNearest(center, rayDirection);

        Reference reference = referenceWithContext.GetReference();
        XYZ intersection = reference.GlobalPoint;

        // Create line segment from the start point and intersection point.
        Line result = Line.CreateBound(center, intersection);
        return result;
    }
}

<Autodesk.Revit.Attributes.Journaling(Autodesk.Revit.Attributes.JournalingMode.NoCommandData)> _
<Autodesk.Revit.Attributes.Transaction(Autodesk.Revit.Attributes.TransactionMode.Manual)> _
Public Class RayProjection
   Implements IExternalCommand
   Public Function Execute(revit As ExternalCommandData, ByRef message As String, elements As ElementSet) As Autodesk.Revit.UI.Result Implements IExternalCommand.Execute
      Dim doc As Document = revit.Application.ActiveUIDocument.Document

      Dim selectedIds As ICollection(Of ElementId) = revit.Application.ActiveUIDocument.Selection.GetElementIds()

      ' If skylight is selected, process it.
      Dim skylight As FamilyInstance = Nothing
      If selectedIds.Count = 1 Then
         For Each id As ElementId In selectedIds
            Dim e As Element = doc.GetElement(id)
            If TypeOf e Is FamilyInstance Then
               Dim instance As FamilyInstance = TryCast(e, FamilyInstance)
               Dim isWindow As Boolean = instance.Category.BuiltInCategory = BuiltInCategory.OST_Windows
               Dim isHostedByRoof As Boolean = instance.Host.Category.BuiltInCategory = BuiltInCategory.OST_Roofs

               If isWindow AndAlso isHostedByRoof Then
                  skylight = instance
               End If
            End If
         Next
      End If

      If skylight Is Nothing Then
         message = "Please select one skylight."
         Return Result.Cancelled
      End If

      ' Calculate the height
      Dim line As Line = CalculateLineAboveFloor(doc, skylight)

      ' Create a model curve to show the distance
      Dim plane As Plane = plane.CreateByNormalAndOrigin(New XYZ(1, 0, 0), line.GetEndPoint(0))
      Dim sketchPlane__1 As SketchPlane = SketchPlane.Create(doc, plane)

      Dim curve As ModelCurve = doc.Create.NewModelCurve(line, sketchPlane__1)

      ' Show a message with the length value
      TaskDialog.Show("Distance", "Distance to floor: " & [String].Format("{0:f2}", line.Length))

      Return Result.Succeeded
   End Function

   ' <summary>
   ' Determines the line segment that connects the skylight to the nearest floor.
   ' </summary>
   ' <returns>The line segment.</returns>
   Private Function CalculateLineAboveFloor(doc As Document, skylight As FamilyInstance) As Line
      ' Find a 3D view to use for the ReferenceIntersector constructor
      Dim collector As New FilteredElementCollector(doc)
      Dim isNotTemplate As Func(Of View3D, Boolean) = Function(v3) Not (v3.IsTemplate)
      Dim view3D As View3D = collector.OfClass(GetType(View3D)).Cast(Of View3D)().First(isNotTemplate)

      ' Use the center of the skylight bounding box as the start point.
      Dim box As BoundingBoxXYZ = skylight.BoundingBox(view3D)
      Dim center As XYZ = box.Min.Add(box.Max).Multiply(0.5)

      ' Project in the negative Z direction down to the floor.
      Dim rayDirection As New XYZ(0, 0, -1)

      Dim filter As New ElementClassFilter(GetType(Floor))

      Dim refIntersector As New ReferenceIntersector(filter, FindReferenceTarget.Face, view3D)
      Dim referenceWithContext As ReferenceWithContext = refIntersector.FindNearest(center, rayDirection)

      Dim reference As Reference = referenceWithContext.GetReference()
      Dim intersection As XYZ = reference.GlobalPoint

      ' Create line segment from the start point and intersection point.
      Dim result As Line = Line.CreateBound(center, intersection)
      Return result
   End Function
End Class

No code example is currently available or this language may not be supported.

No code example is currently available or this language may not be supported.