Using 3D Section Box to set Plan View’s View Range

I was asked if it was possible to set the view range of a floor plan to match the top and bottom extents of a 3d section box. Yes, it is, and here is a little video showing it in action.

• The view on the left is the 3D view with Section Box
• The view on the right is the plan view
• Change the top or bottom of the section box
• Switch to the plan view
• Run the macro and the view range is updated

public void SetViewRange()
{
    Document doc = this.ActiveUIDocument.Document;

    // Get the active view and cast it to a ViewPlan (the API's class for Plan View)
    ViewPlan viewPlan = doc.ActiveView as ViewPlan;

    // Error handling in case the active view is not a plan view
    if (viewPlan == null)
    {
        TaskDialog.Show("Error", "Active view must be a plan view.");
        // return ends the execution of the macro
        return;
    }

    // Get the level that generates the plan view
    Level level = viewPlan.GenLevel;

    View3D view3d = null;
    try
    {
        // if there is no 3D view whose name equals viewPlan.Name, then First() will throw an exception
        view3d = (from v in new FilteredElementCollector(doc).OfClass(typeof(View3D)).Cast<View3D>() where v.Name == viewPlan.Name select v).First();
    }
    catch
    {
        TaskDialog.Show("Error", "There is no 3D view named '" + viewPlan.Name + "'");
        return;
    }

    // Get the BoundingBoxXYZ (a 3D rectangular box) that describes the shape of the Section Box
    BoundingBoxXYZ bbox = view3d.SectionBox;

    // The coordinates of the bounding box are defined relative to a coordinate system specific to the bounding box
    // When setting the view range offsets, the values will need to be relative to the model 

    // This transform translates from coordinate system of the bounding box to the model coordinate system
    Transform transform = bbox.Transform;
    // Transform.Origin defines the origin of the bounding box's coordinate system in the model coordinate system
    // The Z value indicates the vertical offset of the bounding box's coordinate system
    double bboxOriginZ = transform.Origin.Z;

    // BoundingBoxXYZ.Min.Z and BoundingBoxXYZ.Max.Z give the Z values for the bottom and top of the section box
    // Adding the Transform.Origin.Z converts the value to the model coordinate system
    double minZ = bbox.Min.Z + bboxOriginZ;
    double maxZ = bbox.Max.Z + bboxOriginZ;

    // Get the PlanViewRange object from the plan view
    PlanViewRange viewRange = viewPlan.GetViewRange();

    // Set all planes of the view range to use the plan view's level
    viewRange.SetLevelId(PlanViewPlane.TopClipPlane, level.Id);
    viewRange.SetLevelId(PlanViewPlane.CutPlane, level.Id);
    viewRange.SetLevelId(PlanViewPlane.BottomClipPlane, level.Id);
    viewRange.SetLevelId(PlanViewPlane.ViewDepthPlane, level.Id);

    // Set the view depth offset to the difference between the bottom of the section box and
    // the elevation of the level
    viewRange.SetOffset(PlanViewPlane.ViewDepthPlane, minZ - level.Elevation);

    // Set all other offsets to to the difference between the top of the section box and
    // the elevation of the level
    viewRange.SetOffset(PlanViewPlane.TopClipPlane, maxZ - level.Elevation);
    viewRange.SetOffset(PlanViewPlane.CutPlane, maxZ - level.Elevation);
    viewRange.SetOffset(PlanViewPlane.BottomClipPlane, maxZ - level.Elevation);

    using (Transaction t = new Transaction(doc, "Set View Range"))
    {
        t.Start();
        // Set the view range
        viewPlan.SetViewRange(viewRange);
        t.Commit();
    }
}

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