Topic: Transforming Points in model for calculating Viewports center, width height

[Jeff H]

I really not sure what the correct terms to use here so will give an example using drawings from autocad samples

So you take your titleblock and create a annotative block out of it or insert in model space and scale it up to match viewports scale.

So in pic titleblock is scaled by 96 for 1/8" = 1-0'



Lets say the user is prompted to select the window of the viewport in model space to be created in paperspace.
So they select the 2 corners of the yellow rectangle.
So I have the information for settings the Viewports view properties, like Viewport.ViewCenter, etc..., and to calculate its width and height,
but how would I calculate its CenterPoint?
The bottom left corner of titleblock(green rectangle) is 0,0 in paperspace.

Would create viewport in paperspace



Make sense?

[kaefer]

So I have the information for settings the Viewports view properties, like Viewport.ViewCenter, etc..., and to calculate its width and height,
but how would I calculate its CenterPoint?

I'm not sure you have to do that. Let's assume ViewDirection = Vector3d.ZAxis and also UCS = WCS (and let's ignore the block insertion point too), then it seems to be sufficient just to set ViewCenter. The block reference is cloned and placed in paperspace relative to the mid point between the two selected corners, which is paperspace origin, and the center point of the Viewport too.

Excuse the choice of language.

Code - F#: [Select]

1. [<CommandMethod("BLTRPS", CommandFlags.UsePickSet)>]
2. let blockTransPSCmd() =
3.   let doc = acadApp.DocumentManager.MdiActiveDocument
4.   let db = doc.Database
5.   let ed = doc.Editor
6.   let peo = PromptEntityOptions("Select block reference")
7.   peo.SetRejectMessage "Only a block reference allowed."
8.   peo.AllowNone <- true
9.   peo.AddAllowedClass(typeof<BlockReference>, false)
10.   let per = ed.GetEntity peo
11.   if per.Status = PromptStatus.OK then
12.     let ppo = PromptPointOptions("Pick first corner point")
13.     let ppr0 = ed.GetPoint ppo
14.     if per.Status = PromptStatus.OK then
15.       ppo.Message <- "Pick second corner point"
16.       let ppr1 = ed.GetPoint ppo
17.       if per.Status = PromptStatus.OK then
18.         use tr = db.TransactionManager.StartTransaction()
19.         let br = tr.GetObject(per.ObjectId, OpenMode.ForRead) :?> BlockReference
20.         let mp0, mp1 = ppr0.Value, ppr1.Value
21.         let mcen = mp0 + (mp1 - mp0) / 2.
22.         // Rotation and scaling from mspace to pspace
23.         let ms2ps =
24.             Matrix3d.Displacement(Point3d.Origin - mcen) *
25.             Matrix3d.Scaling(1. / br.ScaleFactors.X, mcen) *
26.             Matrix3d.Rotation(-br.Rotation, Vector3d.ZAxis, mcen) *
27.             Matrix3d.WorldToPlane(Vector3d.ZAxis)
28.         let pp0, pp1 = mp0.TransformBy ms2ps, mp1.TransformBy ms2ps
29.         let size = pp1 - pp0
30.         // Rotation for viewcenter from pspace to mspace
31.         let vcen3 =
32.             mcen.TransformBy <|
33.                 Matrix3d.Rotation(-br.Rotation, Vector3d.ZAxis, Point3d.Origin)
34.         let bt = tr.GetObject(db.BlockTableId, OpenMode.ForRead) :?> BlockTable
35.         let ps = tr.GetObject(bt.[BlockTableRecord.PaperSpace], OpenMode.ForWrite) :?> BlockTableRecord
36.         let brnew = br.Clone() :?> BlockReference
37.         brnew.TransformBy ms2ps
38.         ps.AppendEntity brnew |> ignore
39.         tr.AddNewlyCreatedDBObject(brnew, true)
40.         use vp = new Viewport(Width = abs size.X, Height = abs size.Y)
41.         let vpId = ps.AppendEntity vp
42.         tr.AddNewlyCreatedDBObject(vp, true)
43.         tr.Commit()
44.         // Viewport has to be added to database
45.         use tr = db.TransactionManager.StartTransaction()
46.         let vp = tr.GetObject(vpId, OpenMode.ForWrite) :?> Viewport
47.         vp.On <- true
48.         vp.ViewCenter <- Point2d(vcen3.X, vcen3.Y)
49.         // Rotation and scaling of viewport
50.         vp.TwistAngle <- -br.Rotation
51.         vp.ViewHeight <- abs size.Y * br.ScaleFactors.X
52.         tr.Commit()

_{Edit: Fixed issue with scaling}

[Jeff H]

Thanks kaefer,

Been really sick but will get chance today or tomorrow to where I can sit up long enough without throwing up to look at it.

[sybold]

 

been trying to work this out last year, and failed, now i need time to try again.

[Jeff H]

ahhh,

Thanks kaefer,

Was making that harder than it should be.