Viewport To CAD

*Revit to CAD Shared Coordinates*

Helpers to export sheets from Revit to Autocad in shared coordinates

DrawRectangle.cs

		public void DrawRectangle(Document doc, View vpPlan, XYZ _max, XYZ _min){
			
			XYZ min = new XYZ(_min.X, _min.Y,0);
			XYZ max = new XYZ(_max.X, _max.Y,0);
			
			Line l1 = Line.CreateBound(min, new XYZ(max.X, min.Y,0));
			Line l2 = Line.CreateBound(min, new XYZ(min.X, max.Y,0));
			Line l3 = Line.CreateBound(new XYZ(min.X,max.Y,0), max);
			Line l4 = Line.CreateBound(max,new XYZ(max.X,min.Y,0));
			Line l5 = Line.CreateBound(min,max);
			
				doc.Create.NewDetailCurve(vpPlan,l1);
				doc.Create.NewDetailCurve(vpPlan,l2);
				doc.Create.NewDetailCurve(vpPlan,l3);
				doc.Create.NewDetailCurve(vpPlan,l4);
				doc.Create.NewDetailCurve(vpPlan,l5);
		}

FindViewportCenterOnSheet.cs

// Scope:
// 1. Find the Viewport center 
// 2. Find the Viewport's view center

public void FindViewportCenterOnSheet(){
	
	//represents a document opened in the user interface
	UIDocument uidoc = this.ActiveUIDocument;
	//obtain the database level Document (which contains interfaces not related to the UI) 
	Document doc = uidoc.Document;
	
	//***1***
	//a stable reference to a geometric object in a Revit model (?) 
	//https://www.revitapidocs.com/2015/d28155ae-817b-1f31-9c3f-c9c6a28acc0d.htm
	Reference viewportRef = uidoc.Selection.PickObject(ObjectType.Element,"Select a Viewport");
	
	//The data in a Revit document consists primarily of a collection of elements. An element usually 
	//corresponds to a single component of a building or drawing, such as a wall, door, or dimension, 
	//but it can also be something more abstract, like a wall type or a view. Every element in a document has a unique ID, 
	//represented by the ElementId class.
	Element viewportElement = doc.GetElement(viewportRef);
	
	//Cast the Element to a Viewport 
	//https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/types/casting-and-type-conversions
	Viewport viewport = viewportElement as Viewport;
	
	//Find the Viewport center
	XYZ vpMax = viewport.GetBoxOutline().MaximumPoint;
	XYZ vpMin = viewport.GetBoxOutline().MinimumPoint;
	XYZ vpCen = vpMax - vpMin;
	
	double vpX = Convert.ToInt16(viewport.GetBoxCenter().X * 304.8);
	double vpY = Convert.ToInt16(viewport.GetBoxCenter().Y * 304.8);
	double vpZ = Convert.ToInt16(viewport.GetBoxCenter().Z * 304.8);
	
	TaskDialog.Show("Viewport Center", String.Format("{0}, {1}, {2}", vpX, vpY, vpZ ));
	
	//Draw a rectangle. For the using statement see: https://thebuildingcoder.typepad.com/blog/2012/04/scope-and-dispose-transactions.html
	//in short: is the safest way to guarantee that scoped objects are destroyed in the proper order.
	using (Transaction t = new Transaction(doc, "Draw Rectangle")){
		
		t.Start();
		
		DrawRectangle(doc, doc.ActiveView, vpMax,vpMin);
		
		t.Commit();
	}

	//***2***
	//Let's now find the View center
	
	//We can get the view from the Viewport.ViewId
	View plan = doc.GetElement(viewport.ViewId) as View;
	
	//
	ViewCropRegionShapeManager vcr = plan.GetCropRegionShapeManager();
				
	CurveLoop cloop = vcr.GetAnnotationCropShape();
	List<XYZ> pts = new List<XYZ>();

	foreach (Curve crv in cloop)
	{
		pts.Add(crv.GetEndPoint(0));
		pts.Add(crv.GetEndPoint(1));
	}

	//View centroid
	XYZ center = GetCentroid(pts, pts.Count);
	
	//See the difference
	BoundingBoxXYZ bbox = plan.get_BoundingBox(plan);
	XYZ centroid = bbox.Max - bbox.Min;
	
	double centerX = (center.X * 304.8);
	double centerY = (center.Y * 304.8);
	double centerZ = (center.Z * 304.8);

	using (Transaction t = new Transaction(doc, "tes")){
		
		t.Start();
		
		//Line l = Line.CreateBound(new XYZ(0,0,0),new XYZ(centroid.X, centroid.Y,0));
		Line l = Line.CreateBound(new XYZ(0,0,0),new XYZ(center.X, center.Y,0));
		
		doc.Create.NewDetailCurve(plan, l);
		
		t.Commit();
	}
	
	//TaskDialog.Show("Viewport Center", String.Format("{0}, {1}, {2}", vpX, vpY, vpZ ));
	//TaskDialog.Show("Viewport Center", center.ToString());
	TaskDialog.Show("Viewport Center", String.Format("{0}, {1}, {2}", centerX, centerY, centerZ));
}

GetPointsCentroid.cs

// https://stackoverflow.com/questions/9815699/how-to-calculate-centroid
// http://coding-experiments.blogspot.com/2009/09/xna-quest-for-centroid-of-polygon.html

public static XYZ GetCentroid(List<XYZ> nodes, int count)
        {
            double x = 0, y = 0, area = 0, k;
            XYZ a, b = nodes[count - 1];

            for (int i = 0; i < count; i++)
            {
                a = nodes[i];

                k = a.Y * b.X - a.X * b.Y;
                area += k;
                x += (a.X + b.X) * k;
                y += (a.Y + b.Y) * k;

                b = a;
            }
            area *= 3;

            return (area == 0) ? XYZ.Zero : new XYZ(x /= area, y /= area, 0);
        }