Define the Hatch Boundaries (.NET)

Once the Hatch object is created, the hatch boundaries can be added. Boundaries can be any combination of lines, arcs, circles, 2D polylines, ellipses, splines, and regions.

The first boundary added must be the outer boundary, which defines the outermost limits to be filled by the hatch. To add the outer boundary, use the AppendLoop method with the HatchLoopTypes.Outermost constant for the type of loop to append.

Once the outer boundary is defined, you can continue adding additional boundaries. Add inner boundaries using the AppendLoop method with the HatchLoopTypes.Default constant.

Inner boundaries define islands within the hatch. How these islands are handled by the Hatch object depends on the setting of the HatchStyle property. The HatchStyle property can be set to one of the following conditions:

Hatch style definitions
HatchStyle	Condition	Description
	Normal (HatchStyle.Normal)	Specifies standard style, or normal. This option hatches inward from the outermost area boundary. If AutoCAD encounters an internal boundary, it turns off hatching until it encounters another boundary. This is the default setting for the HatchStyle property.
	Outer (HatchStyle.Outer)	Fills the outermost areas only. This style also hatches inward from the area boundary, but it turns off hatching if it encounters an internal boundary and does not turn it back on again.
	Ignore (HatchStyle.Ignore)	Ignores internal structure. This option hatches through all internal objects.

When you have finished defining the hatch it must be evaluated before it can be displayed. Use the EvaluateHatch method to do this.

Create a Hatch object

The following example creates an associated hatch in Model space. Once the hatch has been created, you can change the size of the circle that the hatch is associated with. The hatch will change to match the size of the circle.

VB.NET

Imports Autodesk.AutoCAD.Runtime
Imports Autodesk.AutoCAD.ApplicationServices
Imports Autodesk.AutoCAD.DatabaseServices
Imports Autodesk.AutoCAD.Geometry
 
<CommandMethod("AddHatch")> _
Public Sub AddHatch()
    '' 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 circle object for the closed boundary to hatch
        Using acCirc As Circle = New Circle()
            acCirc.Center = New Point3d(3, 3, 0)
            acCirc.Radius = 1

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

            '' Adds the circle to an object id array
            Dim acObjIdColl As ObjectIdCollection = New ObjectIdCollection()
            acObjIdColl.Add(acCirc.ObjectId)

            '' Create the hatch object and append it to the block table record
            Using acHatch As Hatch = New Hatch()
                acBlkTblRec.AppendEntity(acHatch)
                acTrans.AddNewlyCreatedDBObject(acHatch, True)

                '' Set the properties of the hatch object
                '' Associative must be set after the hatch object is appended to the 
                '' block table record and before AppendLoop
                acHatch.SetHatchPattern(HatchPatternType.PreDefined, "ANSI31")
                acHatch.Associative = True
                acHatch.AppendLoop(HatchLoopTypes.Outermost, acObjIdColl)
                acHatch.EvaluateHatch(True)
            End Using
        End Using

        '' Save the new object 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("AddHatch")]
public static void AddHatch()
{
    // 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 circle object for the closed boundary to hatch
        using (Circle acCirc = new Circle())
        {
            acCirc.Center = new Point3d(3, 3, 0);
            acCirc.Radius = 1;

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

            // Adds the circle to an object id array
            ObjectIdCollection acObjIdColl = new ObjectIdCollection();
            acObjIdColl.Add(acCirc.ObjectId);

            // Create the hatch object and append it to the block table record
            using (Hatch acHatch = new Hatch())
            {
                acBlkTblRec.AppendEntity(acHatch);
                acTrans.AddNewlyCreatedDBObject(acHatch, true);

                // Set the properties of the hatch object
                // Associative must be set after the hatch object is appended to the 
                // block table record and before AppendLoop
                acHatch.SetHatchPattern(HatchPatternType.PreDefined, "ANSI31");
                acHatch.Associative = true;
                acHatch.AppendLoop(HatchLoopTypes.Outermost, acObjIdColl);
                acHatch.EvaluateHatch(true);
            }
        }

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

VBA/ActiveX Code Reference

Sub AddHatch()
    Dim hatchObj As AcadHatch
    Dim patternName As String
    Dim PatternType As Long
    Dim bAssociativity As Boolean
 
    ' Define the hatch
    patternName = "ANSI31"
    PatternType = 0
    bAssociativity = True
 
    ' Create the associative Hatch object
    Set hatchObj = ThisDrawing.ModelSpace.AddHatch _
                       (PatternType, patternName, bAssociativity)
 
    ' Create the outer boundary for the hatch. (a circle)
    Dim outerLoop(0 To 0) As AcadEntity
    Dim center(0 To 2) As Double
    Dim radius As Double
    center(0) = 3: center(1) = 3: center(2) = 0
    radius = 1
    Set outerLoop(0) = ThisDrawing.ModelSpace. _
                           AddCircle(center, radius)
 
    ' Append the outerboundary to the hatch
    ' object, and display the hatch
    hatchObj.AppendOuterLoop (outerLoop)
    hatchObj.Evaluate
    ThisDrawing.Regen True
End Sub