You define a user coordinate system ( UCS ) object to change the location of the (0, 0, 0) origin point and the orientation of the XY plane and Z axis. You can locate and orient a UCS anywhere in 3D space, and you can define, save, and recall as many user coordinate systems as you require. Coordinate input and display are relative to the current UCS.
To indicate the origin and orientation of the UCS, you can display the UCS icon at the UCS origin point using the IconAtOrigin property of a Viewport object or the UCSICON system variable. If the UCS icon is turned on (IconVisible property) and is not displayed at the origin, it is displayed at the WCS coordinate defined by the UCSORG system variable.
You can create a new user coordinate system using the Add method of the UCSTable object. This method requires four values as input: the coordinate of the origin, a coordinate on the X and Y axes, and the name of the UCS.
All coordinates in the AutoCAD ® ActiveX Automation are entered in the world coordinate system. Use the GetUCSMatrix method to return the transformation matrix of a given UCS. Use this transformation matrix to find the equivalent WCS coordinates.
To make a UCS active, use the ActiveUCS property on the Document object. If changes are made to the active UCS, the new UCS object must be reset as the active UCS for the changes to appear. To reset the active UCS, simply call the ActiveUCS property again with the updated UCS object.
The following subroutine creates a new UCS and sets it as the active UCS for the drawing. It then asks the user to pick a point in the drawing, and returns both WCS and UCS coordinates for the point.
Imports Autodesk.AutoCAD.Runtime
Imports Autodesk.AutoCAD.ApplicationServices
Imports Autodesk.AutoCAD.DatabaseServices
Imports Autodesk.AutoCAD.EditorInput
Imports Autodesk.AutoCAD.Geometry
<CommandMethod("NewUCS")> _
Public Sub NewUCS()
'' Get the current document and database, and start a transaction
Dim acDoc As Document = Application.DocumentManager.MdiActiveDocument
Dim acCurDb As Database = acDoc.Database
Using acTrans As Transaction = acCurDb.TransactionManager.StartTransaction()
'' Open the UCS table for read
Dim acUCSTbl As UcsTable
acUCSTbl = acTrans.GetObject(acCurDb.UcsTableId, _
OpenMode.ForRead)
Dim acUCSTblRec As UcsTableRecord
'' Check to see if the "New_UCS" UCS table record exists
If acUCSTbl.Has("New_UCS") = False Then
acUCSTblRec = New UcsTableRecord()
acUCSTblRec.Name = "New_UCS"
'' Open the UCSTable for write
acUCSTbl.UpgradeOpen()
'' Add the new UCS table record
acUCSTbl.Add(acUCSTblRec)
acTrans.AddNewlyCreatedDBObject(acUCSTblRec, True)
acUCSTblRec.Dispose()
Else
acUCSTblRec = acTrans.GetObject(acUCSTbl("New_UCS"), _
OpenMode.ForWrite)
End If
acUCSTblRec.Origin = New Point3d(4, 5, 3)
acUCSTblRec.XAxis = New Vector3d(1, 0, 0)
acUCSTblRec.YAxis = New Vector3d(0, 1, 0)
'' Open the active viewport
Dim acVportTblRec As ViewportTableRecord
acVportTblRec = acTrans.GetObject(acDoc.Editor.ActiveViewportId, _
OpenMode.ForWrite)
'' Display the UCS Icon at the origin of the current viewport
acVportTblRec.IconAtOrigin = True
acVportTblRec.IconEnabled = True
'' Set the UCS current
acVportTblRec.SetUcs(acUCSTblRec.ObjectId)
acDoc.Editor.UpdateTiledViewportsFromDatabase()
'' Display the name of the current UCS
Dim acUCSTblRecActive As UcsTableRecord
acUCSTblRecActive = acTrans.GetObject(acVportTblRec.UcsName, _
OpenMode.ForRead)
Application.ShowAlertDialog("The current UCS is: " & _
acUCSTblRecActive.Name)
Dim pPtRes As PromptPointResult
Dim pPtOpts As PromptPointOptions = New PromptPointOptions("")
'' Prompt for a point
pPtOpts.Message = vbLf & "Enter a point: "
pPtRes = acDoc.Editor.GetPoint(pPtOpts)
Dim pPt3dWCS As Point3d
Dim pPt3dUCS As Point3d
'' If a point was entered, then translate it to the current UCS
If pPtRes.Status = PromptStatus.OK Then
pPt3dWCS = pPtRes.Value
pPt3dUCS = pPtRes.Value
'' Translate the point from the current UCS to the WCS
Dim newMatrix As Matrix3d = New Matrix3d()
newMatrix = Matrix3d.AlignCoordinateSystem(Point3d.Origin, _
Vector3d.XAxis, _
Vector3d.YAxis, _
Vector3d.ZAxis, _
acVportTblRec.Ucs.Origin, _
acVportTblRec.Ucs.Xaxis, _
acVportTblRec.Ucs.Yaxis, _
acVportTblRec.Ucs.Zaxis)
pPt3dWCS = pPt3dWCS.TransformBy(newMatrix)
Application.ShowAlertDialog("The WCS coordinates are: " & vbLf & _
pPt3dWCS.ToString() & vbLf & _
"The UCS coordinates are: " & vbLf & _
pPt3dUCS.ToString())
End If
'' Save the new objects to the database
acTrans.Commit()
End Using
End Sub
using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Geometry;
[CommandMethod("NewUCS")]
public static void NewUCS()
{
// Get the current document and database, and start a transaction
Document acDoc = Application.DocumentManager.MdiActiveDocument;
Database acCurDb = acDoc.Database;
using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
{
// Open the UCS table for read
UcsTable acUCSTbl;
acUCSTbl = acTrans.GetObject(acCurDb.UcsTableId,
OpenMode.ForRead) as UcsTable;
UcsTableRecord acUCSTblRec;
// Check to see if the "New_UCS" UCS table record exists
if (acUCSTbl.Has("New_UCS") == false)
{
acUCSTblRec = new UcsTableRecord();
acUCSTblRec.Name = "New_UCS";
// Open the UCSTable for write
acUCSTbl.UpgradeOpen();
// Add the new UCS table record
acUCSTbl.Add(acUCSTblRec);
acTrans.AddNewlyCreatedDBObject(acUCSTblRec, true);
acUCSTblRec.Dispose();
}
else
{
acUCSTblRec = acTrans.GetObject(acUCSTbl["New_UCS"],
OpenMode.ForWrite) as UcsTableRecord;
}
acUCSTblRec.Origin = new Point3d(4, 5, 3);
acUCSTblRec.XAxis = new Vector3d(1, 0, 0);
acUCSTblRec.YAxis = new Vector3d(0, 1, 0);
// Open the active viewport
ViewportTableRecord acVportTblRec;
acVportTblRec = acTrans.GetObject(acDoc.Editor.ActiveViewportId,
OpenMode.ForWrite) as ViewportTableRecord;
// Display the UCS Icon at the origin of the current viewport
acVportTblRec.IconAtOrigin = true;
acVportTblRec.IconEnabled = true;
// Set the UCS current
acVportTblRec.SetUcs(acUCSTblRec.ObjectId);
acDoc.Editor.UpdateTiledViewportsFromDatabase();
// Display the name of the current UCS
UcsTableRecord acUCSTblRecActive;
acUCSTblRecActive = acTrans.GetObject(acVportTblRec.UcsName,
OpenMode.ForRead) as UcsTableRecord;
Application.ShowAlertDialog("The current UCS is: " +
acUCSTblRecActive.Name);
PromptPointResult pPtRes;
PromptPointOptions pPtOpts = new PromptPointOptions("");
// Prompt for a point
pPtOpts.Message = "\nEnter a point: ";
pPtRes = acDoc.Editor.GetPoint(pPtOpts);
Point3d pPt3dWCS;
Point3d pPt3dUCS;
// If a point was entered, then translate it to the current UCS
if (pPtRes.Status == PromptStatus.OK)
{
pPt3dWCS = pPtRes.Value;
pPt3dUCS = pPtRes.Value;
// Translate the point from the current UCS to the WCS
Matrix3d newMatrix = new Matrix3d();
newMatrix = Matrix3d.AlignCoordinateSystem(Point3d.Origin,
Vector3d.XAxis,
Vector3d.YAxis,
Vector3d.ZAxis,
acVportTblRec.Ucs.Origin,
acVportTblRec.Ucs.Xaxis,
acVportTblRec.Ucs.Yaxis,
acVportTblRec.Ucs.Zaxis);
pPt3dWCS = pPt3dWCS.TransformBy(newMatrix);
Application.ShowAlertDialog("The WCS coordinates are: \n" +
pPt3dWCS.ToString() + "\n" +
"The UCS coordinates are: \n" +
pPt3dUCS.ToString());
}
// Save the new objects to the database
acTrans.Commit();
}
}
Sub NewUCS()
' Define the variables we will need
Dim ucsObj As AcadUCS
Dim origin(0 To 2) As Double
Dim xAxisPnt(0 To 2) As Double
Dim yAxisPnt(0 To 2) As Double
' Define the UCS points
origin(0) = 4: origin(1) = 5: origin(2) = 3
xAxisPnt(0) = 5: xAxisPnt(1) = 5: xAxisPnt(2) = 3
yAxisPnt(0) = 4: yAxisPnt(1) = 6: yAxisPnt(2) = 3
' Add the UCS to the
' UserCoordinatesSystems collection
Set ucsObj = ThisDrawing.UserCoordinateSystems. _
Add(origin, xAxisPnt, yAxisPnt, "New_UCS")
' Display the UCS icon
ThisDrawing.ActiveViewport.UCSIconAtOrigin = True
ThisDrawing.ActiveViewport.UCSIconOn = True
' Make the new UCS the active UCS
ThisDrawing.ActiveUCS = ucsObj
MsgBox "The current UCS is : " & ThisDrawing.ActiveUCS.Name _
& vbCrLf & " Pick a point in the drawing."
' Find the WCS and UCS coordinate of a point
Dim WCSPnt As Variant
Dim UCSPnt As Variant
WCSPnt = ThisDrawing.Utility.GetPoint(, "Enter a point: ")
UCSPnt = ThisDrawing.Utility.TranslateCoordinates _
(WCSPnt, acWorld, acUCS, False)
MsgBox "The WCS coordinates are: " & WCSPnt(0) & ", " _
& WCSPnt(1) & ", " & WCSPnt(2) & vbCrLf & _
"The UCS coordinates are: " & UCSPnt(0) & ", " _
& UCSPnt(1) & ", " & UCSPnt(2)
End Sub