Get FaceWall Centerline Curve(s) as Cut by View

[kudzuman]

I would like to draw a DetailCurve in the center of all Walls and FaceWalls visible in a view.

Using a FilteredElementCollector specifying a ViewID, I get all visible Walls and FaceWalls.

For the Walls I can get their Location and clone it.

For FaceWalls, Location does not return a curve so I cannot clone it.

So for FaceWalls I though maybe I could use GeometryElement with my view specified in the Options so that I get roughly what that FaceWall looks like at that view's cut section. But how do I use that to get a Curve or likely a collection of Curves to clone into a DetailCurve(s) that represent its centerline or edge along that cut plane?

One thought was to get an Interior and/or Exterior Face using HostObjectUtils.GetSideFaces(FaceWall, ShellLayerType.Interior) and then find all curves from GeometryElement that have more than 1 point intersecting that Face. I figure if a curve generated this way has its beginning and end on the face then its whole is likely on that face. But I don't know if that is possible or how to do that and would appreciate some help. I am still reading/struggling with/learning how to iterate through what GeometryElement returns for FaceWalls.

[BenoitE&A]

Hey Kudzuman,

I usually use only the LocationCurve of the walls and translate it to the faces of the walls to get the faces.

If you have a list of walls given by your FilteredElementCollector named myVisibleWalls :

List<Wall> myVisibleWalls;

for(int i =0; i< myVisibleWalls.Count ; i++)

{

Line myLine = (myVisibleWalls[i].Location as LocationCurve).Curve as Line;

// Creation of the normal vector to the location Line

XYZ normalVector = XYZ.BasisZ.CrossProduct(myLine.Direction);

// Set it to the right width (half of wall width)

normalVector = normalVector / normalVector.GetLength() * myVisibleWalls[i].WallType.Width /2;

// Translate myLine to get the 2 faces

Line l1= myLine.CreateTransformed(Transform.CreateTranslation(normalVector)) as Line;

Line l2= myLine.CreateTransformed(Transform.CreateTranslation(-normalVector)) as Line;

// You have your lines

}

Of course it does apply only to linear walls. 

If anybody has a better solution I am interested !

Benoit

[kudzuman]

Like I said the Walls I can get what I want. it is FaceWalls that I am struggling with.

[BenoitE&A]

Well the lines I create in my script are your FaceWalls cut by your view, right ? So they could be the detail lines you are searching for... Or you can use them as location for the lines you want to create.

[kudzuman]

FaceWall objects are not Wall objects. Their Location properties are different. What you propose is dealing with Wall objects and not FaceWall objects.

[JimJia]

I'm afraid this is no safe way to calculate the center line of facewall accurately because the facewall maybe sloped, or non-planar....

However, we do can calculate the centerline  approximately via Revit API, the code below demonstrates one workaround(note that the code is not safe, this is just code snippet):

The main points are: use  BooleanOperationsUtils.CutWithHalfSpace() to cut the solid of facewall by view plane, and then use the intersect curve of interior, exterior face to calculate the centerline.

I also attached the macro sample for your reference. 

		/// <summary>
		/// Retrieve center line of facewall cut by view approximately 
		/// </summary>
		public void FindFacewallCenterLine()
		{
			// find one facewall
			UIDocument uiDoc = new UIDocument(this.Document);
			Element wall = this.Document.GetElement(uiDoc.Selection.PickObject(ObjectType.Element, "Select one face wall"));
			//
			// get solid of face wall
			Options opt = new Options();
			opt.View = this.ActiveView;			
			Solid wallSolid = null;
			GeometryElement geomElem = wall.get_Geometry(opt);
			foreach(GeometryObject go in geomElem)
			{
				if(go is Solid)
				{
					wallSolid = go as Solid;
					break;				
				}			
			}
			//
			// create plane with current plane view, the normal is BasisZ
			Plane viewPlane = new Plane(XYZ.BasisZ, this.Document.ActiveView.Origin);
			//
			// cut the face wall solid with the view plane
			Solid cutSolid = BooleanOperationsUtils.CutWithHalfSpace(wallSolid, viewPlane);
			//
			// find the face which locates on the plane of the view 
			Face faceOnPlane = null;
			foreach(var face in cutSolid.Faces)
			{
				PlanarFace pface = face as PlanarFace;
				if(null == pface)
					continue;
				
				XYZ normal = pface.ComputeNormal(new UV());
				if(normal.IsAlmostEqualTo(XYZ.BasisZ) || normal.IsAlmostEqualTo(-XYZ.BasisZ))
				{
					faceOnPlane = pface;
					break;
				}
			}
			if(null == faceOnPlane)
				return;
			//
			// find the edges of the face
			List<Curve> edgeCrvs = new List<Curve>();
			foreach(EdgeArray ea in faceOnPlane.EdgeLoops)
			{
					foreach(Edge edge in ea)
					{
						edgeCrvs.Add(edge.AsCurve());
					}
			}
			if(edgeCrvs.Count < 2)
				return;
			//
			// sort curve by length
			var sortCrvs = edgeCrvs.OrderByDescending(x => x.Length).ToList();
			//
			// use the two longest to calcuate the centerline approximately
			// !!! NOTE: this is not safe way, you may use other safe way !!!
			XYZ end0 = (sortCrvs[0].GetEndPoint(0) + sortCrvs[1].GetEndPoint(1)) * 0.5;
			XYZ end1 = (sortCrvs[0].GetEndPoint(1) + sortCrvs[1].GetEndPoint(0)) * 0.5;
			Line centerLine = Line.CreateBound(end0, end1);
			//
			// draw the center line for debug
			using(Transaction tran = new Transaction(this.Document, "Curves"))
			{
				tran.Start();
				this.Document.Create.NewModelCurve(centerLine, this.ActiveView.SketchPlane);
				tran.Commit();
			}
		}

[kudzuman]

Thanks Jim.

That helped me understand what I was reading about geometry in all the documentation. However, the unsafe aspects you mention are what I am really after. The trouble I run into with your solution is that the longest edgeloops are not always straight and are likely HermiteSplines in complex double curved FaceWalls. I could offset them maybe based on the wall family's thickness but what I am after is a DetailCurve for that centerline and now I am stuck trying to convert a HermiteSpline curve into a DetailCurve. Is that possible?

In the UI there is a Convert Line Tool but is there an API process that is similar?

[JimJia]

Yes, it's possible to convert the geometry curve to curve element; for example, you can create  detailcurve element with API: Document.Create.NewDetailCurve(), see code snippet below:

			// sort intersect curves by length
			var sortCrvs = edgeCrvs.OrderByDescending(x => x.Length).ToList();
			//
			// create detail curve element with the geometry curve.
			using(Transaction tran = new Transaction(this.Document, "Curves"))
			{
				tran.Start();
				foreach(Curve crv in sortCrvs)
				{
					this.Document.Create.NewDetailCurve(this.Document.ActiveView, crv);
				}
				tran.Commit();
			}

[kudzuman]

That is the code I have but it doesn't work when the Curve (crv) is a HermiteSpline.

If the FaceWall was placed on a double curved surface then the resulting edgeLoops from cutting the solid with the CutWithHalfSpace process are HermiteSplines. When you pass a HermiteSpline Curve to Create.NewDetailCurve, nothing gets created.

I could probably make a model line from a HermiteSpline but I need a Detail line. That is why I was asking if there is a Convert Line Types method/process in the API like there is in the UI.

[Revitalizer]

Hi,

see

https://forums.autodesk.com/t5/revit-api-forum/how-to-convert-3d-curve-to-2d-curve/td-p/7492893

Revitalizer

[kudzuman]

That link seems like it would help but getting the detail curve out of the DetailCurveArray returns Nothing even though the size is > 0.

Below is a piece of my code where I am having trouble.

cv is a curve I get earlier from a process using BooleanOperationsUtils.CutWithHalfSpace and finding EdgeLoops as posted by Jim.

vwf is the current view

Dim cve As DetailCurve = Nothing
 If TypeOf cv Is HermiteSpline Then
    Dim mca As ModelCurveArray = New ModelCurveArray()
    mca.Append(doc.Create.NewModelCurve(cv, vwf.SketchPlane))
    Dim dca As DetailCurveArray = doc.ConvertModelToDetailCurves(vwf, mca)
    Dim dcai As DetailCurveArrayIterator = dca.ForwardIterator
    While dcai.MoveNext()
         cve = TryCast(dcai.Current, DetailCurve) 'dcai.size = 1 but Current = Nothing
    End While
End If

What is the best way to get the DetailCurve element out of the DetailCurveArray?

Is there maybe a better way than above to turn that HermiteSpline Curve into a DetailCurve?

[Revitalizer · Accepted solution]

Hi,

RevitAPI.cm says, regarding the NewModelCurve method and its return value:

"If successful a new model line element. Otherwise a null reference (Nothing in Visual Basic)."

Revit just cannot create a ModelCurve by the input curve.

Which options do you have?

• You could try to convert the HermiteSpline to a NurbSpline and (try to) use this as the NewModeCurve input (NurbSpline.CreateCurve method).
• You could get points from the input HermiteSpline, project them onto your view plane and create a new HermiteSpline by this points.

That's all some sort of approximation, I fear.

Revitalizer

[kudzuman]

Using NurbSpline.Create and passing the HermiteSpline object is close enough for what I need. Thanks.

The documentaion says you can't make certain curves depending on the view but doesn't elaborate on which kinds of curves and which kinds of views. I suppose HermiteSplines just can't be made into DetailCurves in plan views. So thanks for verifying and providing a good enough work around.