Rotate in 3D (.NET)

With the TransformBy method of an object and the Rotation method of a Matrix, you can rotate objects in 2D about a specified point. The direction of rotation for 2D objects is around the Z axis. For 3D objects, the axis of rotation is not limited to the Z axis. When using the Rotation method instead of using the Z axis for the rotation axis, you specify a specific 3D vector.

Create a 3D box and rotate it about an axis

This example creates a 3D box. It then defines the axis for rotation and finally rotates the box 30 degrees about the axis.

VB.NET

Imports Autodesk.AutoCAD.Runtime
Imports Autodesk.AutoCAD.ApplicationServices
Imports Autodesk.AutoCAD.DatabaseServices
Imports Autodesk.AutoCAD.Geometry
 
<CommandMethod("Rotate_3DBox")> _
Public Sub Rotate_3DBox()
    '' 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 Block table for read
        Dim acBlkTbl As BlockTable
        acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId, _
                                     OpenMode.ForRead)

        '' Open the Block table record Model space for write
        Dim acBlkTblRec As BlockTableRecord
        acBlkTblRec = acTrans.GetObject(acBlkTbl(BlockTableRecord.ModelSpace), _
                                        OpenMode.ForWrite)

        '' Create a 3D solid box
        Using acSol3D As Solid3d = New Solid3d()
            acSol3D.CreateBox(5, 7, 10)

            '' Position the center of the 3D solid at (5,5,0) 
            acSol3D.TransformBy(Matrix3d.Displacement(New Point3d(5, 5, 0) - _
                                                      Point3d.Origin))

            Dim curUCSMatrix As Matrix3d = acDoc.Editor.CurrentUserCoordinateSystem
            Dim curUCS As CoordinateSystem3d = curUCSMatrix.CoordinateSystem3d

            '' Rotate the 3D solid 30 degrees around the axis that is
            '' defined by the points (-3,4,0) and (-3,-4,0)
            Dim vRot As Vector3d = New Point3d(-3, 4, 0). _
                                   GetVectorTo(New Point3d(-3, -4, 0))

            acSol3D.TransformBy(Matrix3d.Rotation(0.5236, _
                                                  vRot, _
                                                  New Point3d(-3, 4, 0)))

            '' Add the new object to the block table record and the transaction
            acBlkTblRec.AppendEntity(acSol3D)
            acTrans.AddNewlyCreatedDBObject(acSol3D, True)
        End Using

        '' Save the new objects to the database
        acTrans.Commit()
    End Using
End Sub

C#

using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
 
[CommandMethod("Rotate_3DBox")]
public static void Rotate_3DBox()
{
    // 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 Block table for read
        BlockTable acBlkTbl;
        acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId,
                                        OpenMode.ForRead) as BlockTable;

        // Open the Block table record Model space for write
        BlockTableRecord acBlkTblRec;
        acBlkTblRec = acTrans.GetObject(acBlkTbl[BlockTableRecord.ModelSpace],
                                        OpenMode.ForWrite) as BlockTableRecord;

        // Create a 3D solid box
        using (Solid3d acSol3D = new Solid3d())
        {
            acSol3D.CreateBox(5, 7, 10);

            // Position the center of the 3D solid at (5,5,0) 
            acSol3D.TransformBy(Matrix3d.Displacement(new Point3d(5, 5, 0) -
                                                        Point3d.Origin));

            Matrix3d curUCSMatrix = acDoc.Editor.CurrentUserCoordinateSystem;
            CoordinateSystem3d curUCS = curUCSMatrix.CoordinateSystem3d;

            // Rotate the 3D solid 30 degrees around the axis that is
            // defined by the points (-3,4,0) and (-3,-4,0)
            Vector3d vRot = new Point3d(-3, 4, 0).
                            GetVectorTo(new Point3d(-3, -4, 0));

            acSol3D.TransformBy(Matrix3d.Rotation(0.5236,
                                                    vRot,
                                                    new Point3d(-3, 4, 0)));

            // Add the new object to the block table record and the transaction
            acBlkTblRec.AppendEntity(acSol3D);
            acTrans.AddNewlyCreatedDBObject(acSol3D, true);
        }

        // Save the new objects to the database
        acTrans.Commit();
    }
}

VBA/ActiveX Code Reference

Sub Rotate_3DBox()
    Dim boxObj As Acad3DSolid
    Dim length As Double
    Dim width As Double
    Dim height As Double
    Dim center(0 To 2) As Double
 
    ' Define the box
    center(0) = 5: center(1) = 5: center(2) = 0
    length = 5
    width = 7
    height = 10
 
    ' Create the box object in model space
    Set boxObj = ThisDrawing.ModelSpace. _
                     AddBox(center, length, width, height)
 
    ' Define the rotation axis with two points
    Dim rotatePt1(0 To 2) As Double
    Dim rotatePt2(0 To 2) As Double
    Dim rotateAngle As Double
    rotatePt1(0) = -3: rotatePt1(1) = 4: rotatePt1(2) = 0
    rotatePt2(0) = -3: rotatePt2(1) = -4: rotatePt2(2) = 0
    rotateAngle = 30
    rotateAngle = rotateAngle * 3.141592 / 180#
 
    ' Rotate the box
    boxObj.Rotate3D rotatePt1, rotatePt2, rotateAngle
 
    ZoomAll
End Sub