Create Polar Arrays (.NET)

This example creates a circle, and then performs a polar array of the circle. This creates four circles filling 180 degrees around a base point of (4, 4, 0).

C# Example

using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
 
static Point2d PolarPoints(Point2d pPt, double dAng, double dDist)
{
  return new Point2d(pPt.X + dDist * Math.Cos(dAng),
                     pPt.Y + dDist * Math.Sin(dAng));
}
 
[CommandMethod("PolarArrayObject")]
public static void PolarArrayObject()
{
    // Get the current document and database
    Document acDoc = Application.DocumentManager.MdiActiveDocument;
    Database acCurDb = acDoc.Database;

    // Start a transaction
    using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
    {
        // Open the Block table record 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 circle that is at 2,2 with a radius of 1
        using (Circle acCirc = new Circle())
        {
            acCirc.Center = new Point3d(2, 2, 0);
            acCirc.Radius = 1;

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

            // Create a 4 object polar array that goes a 180
            int nCount = 1;

            // Set a value in radians for 60 degrees
            double dAng = 1.0472;

            // Use (4,4,0) as the base point for the array
            Point2d acPt2dArrayBase = new Point2d(4, 4);

            while (nCount < 4)
            {
                Entity acEntClone = acCirc.Clone() as Entity;

                Extents3d acExts;
                Point2d acPtObjBase;

                // Typically the upper-left corner of an object's extents is used
                // for the point on the object to be arrayed unless it is
                // an object like a circle.
                Circle acCircArrObj = acEntClone as Circle;

                if (acCircArrObj != null)
                {
                    acPtObjBase = new Point2d(acCircArrObj.Center.X,
                                              acCircArrObj.Center.Y);
                }
                else
                {
                    acExts = acEntClone.Bounds.GetValueOrDefault();
                    acPtObjBase = new Point2d(acExts.MinPoint.X,
                                              acExts.MaxPoint.Y);
                }

                double dDist = acPt2dArrayBase.GetDistanceTo(acPtObjBase);
                double dAngFromX = acPt2dArrayBase.GetVectorTo(acPtObjBase).Angle;

                Point2d acPt2dTo = PolarPoints(acPt2dArrayBase,
                                               (nCount * dAng) + dAngFromX,
                                               dDist);

                Vector2d acVec2d = acPtObjBase.GetVectorTo(acPt2dTo);
                Vector3d acVec3d = new Vector3d(acVec2d.X, acVec2d.Y, 0);
                acEntClone.TransformBy(Matrix3d.Displacement(acVec3d));

                /*
                // The following code demonstrates how to rotate each object like
                // the ARRAY command does.
                acExts = acEntClone.Bounds.GetValueOrDefault();
                acPtObjBase = new Point2d(acExts.MinPoint.X,
                                          acExts.MaxPoint.Y);
                
                // Rotate the cloned entity around its upper-left extents point
                Matrix3d curUCSMatrix = acDoc.Editor.CurrentUserCoordinateSystem;
                CoordinateSystem3d curUCS = curUCSMatrix.CoordinateSystem3d;
                acEntClone.TransformBy(Matrix3d.Rotation(nCount * dAng,
                                                         curUCS.Zaxis,
                                                         new Point3d(acPtObjBase.X,
                                                                     acPtObjBase.Y, 0)));
                */

                acBlkTblRec.AppendEntity(acEntClone);
                acTrans.AddNewlyCreatedDBObject(acEntClone, true);

                nCount = nCount + 1;
            }
        }

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