Explode Objects (.NET)

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.

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.

C# Example

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();
    }
}