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.

C# Example

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();
    }
}