Explode Objects

Exploding an object converts the single object to its constituent parts. You use the Explode function to explode an object, and it requires a DBObjectCollection object in which is used to return the resulting objects. For example, exploding a polyline can result in the creation of an object collection that contains multiple lines and arcs.

If a block is exploded, the object collection returned holds the graphical objects in which define the block. After an object is exploded, the original object is left unaltered. If you want the returned objects to replace the original object, the original object must be erased and then the returned objects must be added to a block table record.

For more information about exploding objects, see “Disassociate Compound Objects (Explode)” in the AutoCAD User's Guide.

Explode a polyline

This example creates a lightweight polyline object and then explodes the polyline into its simplest objects. After the polyline is exploded, it is disposed of and the returned objects are added to Model space.

VB.NET

Imports Autodesk.AutoCAD.Runtime

Imports Autodesk.AutoCAD.ApplicationServices

Imports Autodesk.AutoCAD.DatabaseServices

Imports Autodesk.AutoCAD.Geometry

<CommandMethod("ExplodeObject")> _

Public Sub ExplodeObject()

  '' Get the current document and database

  Dim acDoc As Document = Application.DocumentManager.MdiActiveDocument

  Dim acCurDb As Database = acDoc.Database

  '' Start a transaction

  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 lightweight polyline

      Using acPoly As Polyline = New Polyline()

          acPoly.AddVertexAt(0, New Point2d(1, 1), 0, 0, 0)

          acPoly.AddVertexAt(1, New Point2d(1, 2), 0, 0, 0)

          acPoly.AddVertexAt(2, New Point2d(2, 2), 0, 0, 0)

          acPoly.AddVertexAt(3, New Point2d(3, 2), 0, 0, 0)

          acPoly.AddVertexAt(4, New Point2d(4, 4), 0, 0, 0)

          acPoly.AddVertexAt(5, New Point2d(4, 1), 0, 0, 0)

          '' Sets the bulge at index 3

          acPoly.SetBulgeAt(3, -0.5)

          '' Explodes the polyline

          Dim acDBObjColl As DBObjectCollection = New DBObjectCollection()

          acPoly.Explode(acDBObjColl)

          For Each acEnt As Entity In acDBObjColl

              '' Add the new object to the block table record and the transaction

              acBlkTblRec.AppendEntity(acEnt)

              acTrans.AddNewlyCreatedDBObject(acEnt, True)

          Next

          '' Dispose of the in memory polyline

      End Using

      '' 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.Geometry;

[CommandMethod("ExplodeObject")]

public static void ExplodeObject()

  // 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 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 lightweight polyline

      using (Polyline acPoly = new Polyline())

          acPoly.AddVertexAt(0, new Point2d(1, 1), 0, 0, 0);

          acPoly.AddVertexAt(1, new Point2d(1, 2), 0, 0, 0);

          acPoly.AddVertexAt(2, new Point2d(2, 2), 0, 0, 0);

          acPoly.AddVertexAt(3, new Point2d(3, 2), 0, 0, 0);

          acPoly.AddVertexAt(4, new Point2d(4, 4), 0, 0, 0);

          acPoly.AddVertexAt(5, new Point2d(4, 1), 0, 0, 0);

          // Sets the bulge at index 3

          acPoly.SetBulgeAt(3, -0.5);

          // Explodes the polyline

          DBObjectCollection acDBObjColl = new DBObjectCollection();

          acPoly.Explode(acDBObjColl);

          foreach (Entity acEnt in acDBObjColl)

              // Add the new object to the block table record and the transaction

              acBlkTblRec.AppendEntity(acEnt);

              acTrans.AddNewlyCreatedDBObject(acEnt, true);

          // Dispose of the in memory polyline

      // Save the new objects to the database

      acTrans.Commit();

VBA/ActiveX Code Reference