Hatch using the AutoCAD .NET API

Jul 30, 2012

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Below code shows the procedure to create associative hatch using .NET. Before making the hatch “Associative”, hatch object is added to database.

[CommandMethod("testHatch")]
static public void testHatch()
{
    Document doc = Application.DocumentManager.MdiActiveDocument;
    Database db = doc.Database;
    Editor ed = doc.Editor;
 
    using (Transaction Tx = db.TransactionManager.StartTransaction())
    {
        ObjectId ModelSpaceId =
                SymbolUtilityServices.GetBlockModelSpaceId(db);
 
        BlockTableRecord btr = Tx.GetObject(ModelSpaceId,
                          OpenMode.ForWrite) as BlockTableRecord;
 
        Point2d pt = new Point2d(0.0, 0.0);
        Autodesk.AutoCAD.DatabaseServices.Polyline plBox = 
                  new Autodesk.AutoCAD.DatabaseServices.Polyline(4);
 
        plBox.Normal = Vector3d.ZAxis;
        plBox.AddVertexAt(0, pt, 0.0, -1.0, -1.0);
        plBox.AddVertexAt(1, 
                     new Point2d(pt.X + 10, pt.Y), 0.0, -1.0, -1.0);
        plBox.AddVertexAt(2, 
                  new Point2d(pt.X + 10, pt.Y + 5), 0.0, -1.0, -1.0);
        plBox.AddVertexAt(3, 
                      new Point2d(pt.X, pt.Y + 5), 0.0, -1.0, -1.0);
        plBox.Closed = true;
 
        ObjectId pLineId;
        pLineId = btr.AppendEntity(plBox);
        Tx.AddNewlyCreatedDBObject(plBox, true);
 
        ObjectIdCollection ObjIds = new ObjectIdCollection();
        ObjIds.Add(pLineId);
 
        Hatch oHatch = new Hatch();
        Vector3d normal = new Vector3d(0.0, 0.0, 1.0);
        oHatch.Normal = normal;
        oHatch.Elevation = 0.0;
        oHatch.PatternScale = 2.0;
        oHatch.SetHatchPattern(HatchPatternType.PreDefined, "ZIGZAG");
        oHatch.ColorIndex = 1;
 
        btr.AppendEntity(oHatch);
        Tx.AddNewlyCreatedDBObject(oHatch, true);
        //this works ok   
        oHatch.Associative = true;
        oHatch.AppendLoop((int)HatchLoopTypes.Default, ObjIds);
        oHatch.EvaluateHatch(true);
 
        Tx.Commit();
    }
 
}

Comments

7 responses to “Hatch using the AutoCAD .NET API”

Dale Bartlett

November 18, 2012

Many thanks for your excellent examples. With this one I have changed to a user-defined hatch type as follows:
oHatch.SetHatchPattern(HatchPatternType.UserDefined, “_USER”);
oHatch.PatternScale = 1000.0;
oHatch.PatternAngle = MathTools.DegreeToRadian(45.0);
oHatch.PatternSpace = 1000.0;
oHatch.PatternDouble = false;
Unfortunately I get an error eInvalidInput at line oHatch.EvaluateHatch(true);
This is a common problem on the forums, but I have not been able to resolve. Any ideas? Regards, Dale

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rajesh

May 9, 2013

I too have the problem.
Does some one has a solution?

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Ryan Thomas

August 22, 2013

I ran into this problem (and many variations of it) as well. I found that the API is very peculiar about the order in which you set the property values of the hatch.
This worked for me:
Hatch oHatch = new Hatch();
// set the hatch pattern first
oHatch.SetHatchPattern(HatchPatternType.UserDefined, “_USER”);
// set other properties
Vector3d normal = new Vector3d(0.0, 0.0, 1.0);
oHatch.Normal = normal;
oHatch.Elevation = 0.0;
oHatch.PatternScale = 2.0;
oHatch.PatternAngle = 0.0;
oHatch.ColorIndex = 1;
oHatch.Layer = “00-Construction”;
// !!IMPORTANT You must reaffirm the hatch pattern
oHatch.SetHatchPattern(HatchPatternType.UserDefined, “_USER”);
// Then you can proceed as normal
btr.AppendEntity(oHatch);
Tx.AddNewlyCreatedDBObject(oHatch, true);
oHatch.Associative = true;
oHatch.AppendLoop((int)HatchLoopTypes.Default, ObjIds);
oHatch.EvaluateHatch(true);
Tx.Commit();

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Tom DiVittis

February 17, 2017

Some documentation on this order issue would be spectacular. This is costing days (literally) to figure out by the poke and hope method.

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Larn Regis

March 11, 2019

Is there any example how to create a hatch on a region? Especially a region which has a hole in it, like a rectangle with a small circle in it.
ObjectIdCollection acObjIdColl = new ObjectIdCollection();
acObjIdColl.Add(re.ObjectId);
hat.AppendLoop(HatchLoopTypes.Default, acObjIdColl);
re is my region
hat is the hatch
I tried all HatchLoopTypes, but none of them worked.
I always get eInvalidInput on AppendLoop.
Do i have to explode the region back into multiple polylines and then build the hatch from these?

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viru

March 11, 2019

Hi,
see if https://adndevblog.typepad.com/autocad/2013/07/create-hatch-objects-using-trace-boundaries-using-net.html or https://stackoverflow.com/questions/19922816/how-to-cut-a-hole-in-a-hatch-autocad/19930730#19930730 helps.
Thanks

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Larn Regis

March 11, 2019

I got it working by converting the region back into polylines using the example from
https://through-the-interface.typepad.com/through_the_interface/2008/08/creating-a-seri.html
then i had to sort the resulting DBObjectCollection by Area size, so i get the biggest first.
Then i was able to create the hatch using the following code
dbo is the sorted DBObjectCollection with the biggest one first
for (int i = 0; i < dbo.Count; i++)
{
ObjectIdCollection acObjIdColl = new ObjectIdCollection();
Entity e = (Entity)dbo[i];
btr_entity.AppendEntity(e);
acTrans.AddNewlyCreatedDBObject(e, true);//the entity needs to exist in the DB, otherwise AppendLoop throws an eInvalidInput exception
acObjIdColl.Add(e.ObjectId);
if (i == 0)
hat.AppendLoop(HatchLoopTypes.Outermost, acObjIdColl);
else
hat.AppendLoop(HatchLoopTypes.Default, acObjIdColl);
e.Erase(); //remove the temporary Entity again
}

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