Using a geometry viewer in a revit addin to preview results
Dear Jesse,
Thank you for your very pertinent query.
Implementing a decent interactive 3D viewer is certainly doable, though not completely trivial.
Depending on how much interaction you need with it and how closely you want to tie it in to your add-in specific workflows, a stand-alone viewer might provide an easier way to go?
You could use a minimal stand-alone viewer running on Windows or in your browser and hook that up to your Revit add-in.
Here are two untested options:
- Mesh Viewer (C++, Qt, OpenGL) -- http://mview.sourceforge.net
- Online 3D Viewer (JavaScript, three.js) -- https://github.com/kovacsv/Online3DViewer
They both seem a bit too disconnected from .NET and C#, though.
Here are some pointers to a more .NET related resource:
- https://stackoverflow.com/questions/16269665/c-sharp-3d-model-viewer
- https://github.com/helix-toolkit
Here is a detailed discussion of making use of it in WPF context:
Quite a while back, I implemented GeoSnoop, my own simple 2D polygon preview using Windows Forms:
That shows how to set up a minimal Windows form for geometric viewing, with no user interaction, no zoom, no pan, only 2D, so no orbit or anything. It might help provide a simple starting point if you wish to DIY.
I hope this helps.
I look forward to hearing how you end up resolving this.
Thank you!
Best regards,
Jeremy
Dear Jesse,
Some more suggestions, from Rudi @Revitalizer Honke, translated from German for you:
How about using a web browser control embedded in a dockable panel or for to display the 3D model?
Depending on the size of the content to be displayed, you might be able to use a JS library, e.g.:
You can monitor certain events to determine whether an element has been clicked.
If you use the MS-WebControl, there is the ObjectForScripting:
The document property provides access to the DOM, which includes X3D nodes.
You could also look into CEFsharp.
Or directly WPF3D:
https://www.wpftutorial.net/IntroductionTo3D.html
You might encounter performance problems with large models in WPF3D, especially if you don't just want to display a static view, but also rotate it smoothly etc.
If you do not want to display entire building models, just parts of it, e.g., a roof truss, not yet existing as a BIM element, you could build a temporary solid representation for it using GeometryCreationUtilities and extract mesh facets from that for the X3D or WPF3D IndexedFaceSets.
Thanks to Rudi for his suggestions!
I hope this helps even more.
I look forward to hearing how you end up resolving this.
Thank you!
Best regards,
Jeremy
Dear Jesse,
Congratulations on successfully implementing the two versions of the viewer, and thank you for sharing the interesting results.
Regarding your question on performance:
I see several possibly reasons for the 'laggyness'.
On one hand, the Revit API runs only in a single thread, no multi-threading is supported.
On the other hand, I have repeatedly heard of special WPF related issues interacting with Revit.
Maybe either or both of those aspects are affecting the responsiveness.
One option to resolve that issue would be to decouple the viewer from the Revit API completely, as described in the article on using IPC for disentanglement of CEFSharp from Revit:
How important is it for you to have the viewer tightly integrated with Revit?
Does it have to be an add-in?
Could you use IPC as described above to hook up the stand-alone viewer sufficiently closely with Revit to satisfy your needs?
Best regards,
Jeremy
Dear Jesse,
Congratulations on completing this task and thank you very much for letting us know!
I am very glad to hear that you are able to use the OBJ viewer.
Here are some examples of implementing custom exporters:
https://thebuildingcoder.typepad.com/blog/about-the-author.html#5.1
It is pretty straightforward, actually.
Best regards,
Jeremy
Any news n this? Possibly some updated sample code to share? Another question came up today on making use of the Helix viewer with Revit... Thank you!
Wow, looks absolutely great!
Thank you very much for implementing and sharing this!
Would you like to create a GitHub repository for the source code, to make it easier for others to access, discuss, contribute, enhance, raise issues, etc.?
I will gladly promote this to a min blog post on The Building Coder to ensure it gets the visibility it deserves.
Best regards,
Jeremy
Thank you once again for your impressive implementation and kind sharing. I promoted it to a main blog post for maximum exposure:
Communicating geometry back again is not so simple, since Revit is a parametrically driven BIM modeller.
Hence, not geometry driven.
The geometry is just a view resulting from the elements, the constraints between them and their driving parameters.
So, you basically cannot communicate back stupid geometry.
For example, for a wall, you would have to communicate back the upper and lower binding levels, the offsets from those levels, the location curve, etc.
Hi @jeremytammik ,
Thanks for the answer. I tried some things out to see if you only can get a simple wall to the viewer, without the need of running the viewer exe. So directly in Revit. I used as a startpoint the example from @jesse.mom " HelixToolkitInRevitOne" and added the following code:
public Result Execute(ExternalCommandData data, ref string message, ElementSet elemSet)
{
try
{
MainWindow mw = new MainWindow();
UIApplication uiapp = data.Application;
UIDocument uidoc = uiapp.ActiveUIDocument;
Application app = uiapp.Application;
Document doc = uidoc.Document;
{
var meshBuilder = new MeshBuilder();
GeometryModel3D wall = new GeometryModel3D();
IList<Reference> reference = uidoc.Selection.PickObjects(ObjectType.Element, new ImportSelectionFilter(), "Select wall to convert Geometry");
foreach (Reference r in reference)
{
var import = doc.GetElement(r) as Wall;
Autodesk.Revit.DB.Options opt = new Options();
Autodesk.Revit.DB.GeometryElement geomElem = import.get_Geometry(opt);
foreach (GeometryObject geomObj in geomElem)
{
Solid geomSolid = geomObj as Solid;
if (null != geomSolid)
{
foreach (Face geomFace in geomSolid.Faces)
{
Mesh mesh = geomFace.Triangulate();
XYZ[] triangleCorners = new XYZ[3];
for (int i = 0; i < mesh.NumTriangles; ++i)
{
MeshTriangle triangle = mesh.get_Triangle(i);
triangleCorners[0] = triangle.get_Vertex(0);
triangleCorners[1] = triangle.get_Vertex(1);
triangleCorners[2] = triangle.get_Vertex(2);
meshBuilder.AddPolygon(listPoints(triangleCorners));
}
}
}
}
}
ModelVisual3D visual = new ModelVisual3D();
wall.Geometry = meshBuilder.ToMesh();
wall.Material = new DiffuseMaterial(new SolidColorBrush(Colors.Gray));
wall.BackMaterial = new DiffuseMaterial(new SolidColorBrush(Colors.Gray));
Model3DGroup modelGroup = new Model3DGroup();
modelGroup.Children.Add(wall);
visual.Content = modelGroup;
mw.viewPort3d.Children.Add(visual);
mw.Show();
}
}
catch (Exception ex)
{
string exMessage = "No exception message was included";
if (ex.Message != null)
{
if (ex.Message.Length > 0)
{
exMessage = ex.Message;
}
}
TaskDialog.Show("error", exMessage);
}
return Result.Succeeded;
}
public List<Point3D> listPoints(XYZ[] p)
{
List<Point3D> listP = new List<Point3D>();
foreach (XYZ points in p)
{
Point3D p1 = new Point3D(points.X*304.8, points.Y*304.8, points.Z*304.8);
listP.Add(p1);
}
return listP;
}
}When running this code in Revit it is running smoothly unless you zoom to close. But to come real close to the extension "Wood Framing Walls" i think this is a good starting point or you could maybe pass the geometry data to the exe version with some sort of data txt file?
Result running within Revit, faces are looking much nicer this way:
Dear Folkert,
Wow, that looks great!
And very simple, as well.
I definitely agree this is a brilliant starting point.
Why would you want to pass the geometry data to the external exe version?
If you really wanted to, you could either use a file or an in-memory communication channel.
With the geometry data in hand, you can also easily generate a useful generic file format like glTF:
Could you possibly share the entire Visual Studio solution to make it very simple for others to recompile and test?
Thank you!
Best regards,
Jeremy
Dear Folkert,
Thank you for the Visual Studio solution.
I have not done much for or with glTF, but it seems like an extremely efficient and well-thought-out format.
I implemented a data collector for it in the room volume glTF generator:
https://thebuildingcoder.typepad.com/blog/2019/06/room-volume-gltf-generator.html
I left the further processing and final glTF file generation to Michael Beale, though, and I don't know whether he published his results.
Cheers,
Jeremy
