Coordinates for center of viewport in WCS

[joshua.prettyman]

I've been trying to get the center coordinates of a viewport for the last few days with no consistent success.  Any help?

Here's the code I've been using:

using (Database _wdb = HostApplicationServices.WorkingDatabase)
                {
                    using (Transaction _trn = _wdb.TransactionManager.StartTransaction())
                    {
                         Editor _edt = Application.DocumentManager.MdiActiveDocument.Editor;
                        Viewport _cvp = (Viewport)_trn.GetObject(_edt.CurrentViewportObjectId,OpenMode.ForRead);

                        Point2d _try1 = _cvp.ViewCenter;
                        Point3d _try2 = _edt.GetCurrentView().Target;

                    }
              }

 The "ViewCenter" property will occasionally return a valid point, but mostly they both return (0,0) or something similar.  Any help?

[cadMeUp · Accepted solution]

This is one way you can go about it, might seem a little awkward:

Editor _edt = Application.DocumentManager.MdiActiveDocument.Editor;

Viewport _cvp = (Viewport)_trn.GetObject(_edt.CurrentViewportObjectId,OpenMode.ForRead);

_edt.SwitchToModelSpace();

Application.SetSystemVariable("CVPORT", _cvp.Number);

Point3d cenPnt = (Point3d)Application.GetSystemVariable("VIEWCTR");

_edt.SwitchToPaperSpace();

[SENL1362]

maybe this simplified code may help you to do the math as well.

Matrix3d ps2wcs = pvp2.GetModelToPaperTransform().Inverse();

        public static Matrix3d GetModelToPaperTransform(this Autodesk.AutoCAD.DatabaseServices.Viewport pvp)
        {
            Point3d center = new Point3d(pvp.ViewCenter.X, pvp.ViewCenter.Y, 0.0);
            Vector3d v = new Vector3d(pvp.CenterPoint.X - center.X, pvp.CenterPoint.Y - center.Y, 0.0);
            return Matrix3d.Displacement(v)
            * Matrix3d.Scaling(pvp.CustomScale, center)
            * Matrix3d.Rotation(pvp.TwistAngle, Vector3d.ZAxis, Point3d.Origin)
            * Matrix3d.WorldToPlane(new Plane(pvp.ViewTarget, pvp.ViewDirection));
        }

Credits to Gile, see http://www.acadnetwork.com/topic-19.0.html#c2

...

using GeometryExtensions;

...

//Create the Paperspace Viewport boundary in Modelspace.

       [CommandMethod("msPVPByGile")]
        public void CreateViewportBorderInModelSpaceByGile()
        {
            Document doc = Application.DocumentManager.MdiActiveDocument;
            Database db = doc.Database;
            Editor ed = doc.Editor;

            if (db.TileMode)
            {
                ed.WriteMessage("\nStart from within Paperspace!");
                return;
            }
            using (Transaction tr = db.TransactionManager.StartTransaction())
            {
                BlockTable bt = (BlockTable)tr.GetObject(db.BlockTableId, OpenMode.ForRead);
                BlockTableRecord ms = (BlockTableRecord)tr.GetObject(bt[BlockTableRecord.ModelSpace], OpenMode.ForWrite);
                BlockTableRecord ps = (BlockTableRecord)tr.GetObject(bt[BlockTableRecord.PaperSpace], OpenMode.ForWrite);

                LayoutManager layMgr = LayoutManager.Current;
                Layout lay = (Layout)tr.GetObject(layMgr.GetLayoutId(layMgr.CurrentLayout), OpenMode.ForRead);

                Viewport pvp2 = (Viewport)tr.GetObject(lay.GetViewports()[1], OpenMode.ForRead);
                Polyline vpPoly = pvp2.GetPaperSpaceBoundary();
                Polyline msKader = (Polyline)vpPoly.Clone();
                ps.AppendEntity(vpPoly);
                tr.AddNewlyCreatedDBObject(vpPoly, true);

                //Matrix3d ps2wcs = pvp2.PSDCS2DCS() * pvp2.DCS2WCS();
                Matrix3d ps2wcs = pvp2.DCS2WCS() * pvp2.PSDCS2DCS();
                msKader.TransformBy(ps2wcs);

                ms.AppendEntity(msKader);
                tr.AddNewlyCreatedDBObject(msKader, true);

                tr.Commit();
            }
        }

    public static class ViewportExtensions
    {

       public static Polyline GetPaperSpaceBoundary(this Autodesk.AutoCAD.DatabaseServices.Viewport pvp)
        {
            Polyline vpPoly = null;

            if (!pvp.NonRectClipOn)
            {
                Extents3d vpExt = pvp.GeometricExtents;
                vpPoly = new Polyline(4);
                vpPoly.AddVertexAt(0, new Point2d(vpExt.MinPoint.X, vpExt.MinPoint.Y), 0, 0, 0);
                vpPoly.AddVertexAt(1, new Point2d(vpExt.MaxPoint.X, vpExt.MinPoint.Y), 0, 0, 0);
                vpPoly.AddVertexAt(2, new Point2d(vpExt.MaxPoint.X, vpExt.MaxPoint.Y), 0, 0, 0);
                vpPoly.AddVertexAt(3, new Point2d(vpExt.MinPoint.X, vpExt.MaxPoint.Y), 0, 0, 0);
                vpPoly.Closed = true;
            }
            else
            {
                vpPoly = (Polyline)pvp.NonRectClipEntityId.GetObject(OpenMode.ForRead).Clone();
            }
            return vpPoly;
        }

}