Selecting Model Space entities from Paper Space using AutoCAD Selection Sets in C#

By Fenton Webb

I recently posted a blog on Converting Paper Space point to Model Space using AutoCAD.NET and I thought I’d extend that same blog to include using a Paper Space Vport geometry to select all of the Model Space objects that it displays…

So here goes :

// select all entities in Model Space using Paper Space viewport
// by Fenton Webb, DevTech, Autodesk, 02/Apr/2012
[CommandMethod("selectMsFromPs", CommandFlags.NoTileMode)]
static public void selectMsFromPs()
{
    Editor ed = Application.DocumentManager.MdiActiveDocument.Editor;

    // pick a PS Viewport
    PromptEntityOptions opts = new PromptEntityOptions("Pick PS Viewport");
    opts.SetRejectMessage("Must select PS Viewport objects only");
    opts.AddAllowedClass(typeof(Autodesk.AutoCAD.DatabaseServices.Viewport), false);
    PromptEntityResult res = ed.GetEntity(opts);

    if (res.Status == PromptStatus.OK)
    {
        int vpNumber = 0;
        // extract the viewport points
        Point3dCollection psVpPnts = new Point3dCollection();
        using (Autodesk.AutoCAD.DatabaseServices.Viewport psVp = 
            res.ObjectId.Open(OpenMode.ForRead) as Autodesk.AutoCAD.DatabaseServices.Viewport)
        {
            // get the vp number
            vpNumber = psVp.Number;
            // now extract the viewport geometry
            psVp.GetGripPoints(psVpPnts, new IntegerCollection(), new IntegerCollection());
        }

        // let's assume a rectangular vport for now, make the cross-direction grips square
        Point3d tmp = psVpPnts[2];
        psVpPnts[2] = psVpPnts[1];
        psVpPnts[1] = tmp;

        // Transform the PS points to MS points
        ResultBuffer rbFrom = new ResultBuffer(new TypedValue(5003, 3));
        ResultBuffer rbTo = new ResultBuffer(new TypedValue(5003, 2));
        double[] retPoint = new double[] { 0, 0, 0 };
        // loop the ps points
        Point3dCollection msVpPnts = new Point3dCollection();
        foreach (Point3d pnt in psVpPnts)
        {
            // translate from from the DCS of Paper Space (PSDCS) RTSHORT=3 and
            // the DCS of the current model space viewport RTSHORT=2
            acedTrans(pnt.ToArray(), rbFrom.UnmanagedObject, rbTo.UnmanagedObject, 0, retPoint);
            // add the resulting point to the ms pnt array
            msVpPnts.Add(new Point3d(retPoint));
            ed.WriteMessage("\n" + new Point3d(retPoint).ToString());
        }

        // now switch to MS
        ed.SwitchToModelSpace();
        // set the CVPort
        Application.SetSystemVariable("CVPORT", vpNumber);
        // once switched, we can use the normal selection mode to select
        PromptSelectionResult selectionresult = ed.SelectCrossingPolygon(msVpPnts);
        // now switch back to PS
        ed.SwitchToPaperSpace();
    }
}