Here is a list of interesting web adresses for helping you in .NET programming.
This list will be updated regularly by the webmaster.

• AutoCAD .NET Basics, a PDF course from Autodesk University 2007
• A recording of AutoCAD .NET Basics, originally presented as DE205-4 in the ADN Developer track at AU 2008 by Stephen Preston
• A tutorial by Kean Walmsley to get you started @keanw
• AutoCAD .NET developper guide online
• Autodesk .NET forum
• Conversion tool from C# to VB
• Google code search

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Patriiick

You seem to have forgotten one of the better and longstanding forums
http://www.theswamp.org/index.php?board=27.0

Hi,

A new tutorial from Autodesk: My First Plug-in Training

Hi

Stephen Preston may add C# versions (see here).

Waiting this, I purpose my conversion of the provided samples.

The two main differences between VB and C# are syntax and strictness (while VB option 'strict' is off which is the default).
C# is more strongly typed and allows less implicit casts.

KeepAttributesHorizontal - Lesson 1 Completed
Only syntax differences with the VB code.
Prefixing the class fields with an underscore is not requiered (it's only a convention as using 'my*' in VB languages).

using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.Runtime;

namespace KeepAttributesHorizontalCs
{
    public class Commands
    {
        private static KeepStraightOverrule _overrule;

        [CommandMethod("KeepStraight")]
        public static void ImplementOverrule()
        {
            // We only want to create our overrule instance once,
            // so we check if it already exists before we create it
            // (i.e. this may be the 2nd time we've run the command)
            if (_overrule == null)
            {
                // Instantiate our overrule class
                _overrule = new KeepStraightOverrule();
                // Register the overrule
                Overrule.AddOverrule
                    (RXClass.GetClass(typeof(AttributeReference)),
                    _overrule, false);
            }
            // Make sure overruling is turned on so our overrule works
            Overrule.Overruling = true;
        }
    }

    // Our custom overrule class derived from TransformOverrule
    public class KeepStraightOverrule : TransformOverrule
    {
        // We want to change how an AttributeReference responds to being
        // transformed (moved, rotated, etc.), so we override its
        // standard TransformBy function.
        public override void TransformBy(Entity entity, Matrix3d transform)
        {
            // Call the normal TransformBy function for the attribute
            // reference we're overruling.
            base.TransformBy(entity, transform);
            // We know entity must be an AttributeReference because
            // that is the only entity we registered the overrule for.
            AttributeReference attRef = (AttributeReference)entity;
            // Set rotation of attribute reference to 0 (horizontal)
            attRef.Rotation = 0.0;
        }
    }
}


ObjectOrientedSample

using Autodesk.AutoCAD.Runtime;

namespace ObjectOrientedSampleCs
{
    public class Commands
    {
        [CommandMethod("RunTest")]
        public void Test()
        {
            Point pt1 = new Point();
            // Use Step Into on the next line to step into SetLocation
            pt1.SetLocation(10, 10);
            int xVal1 = pt1.X;
            pt1.X = 9;
            int xVal2 = pt1.X;

            NewPoint pt2 = new NewPoint();
            pt2.SetLocation(20, 20);
            int xVal3 = pt2.X;
            pt2.X = 9;
            // Z is new to the NewPoint class
            pt2.Z = 12;
            Point pt3 = pt2;
            // pt3 is variable of type Point, but holds an object of type NewPoint
        }
    }

    public class Point
    {
        private int _xCoord;
        private int _yCoord;

        public void SetLocation(int x, int y)
        {
            _xCoord = x;
            _yCoord = y;
        }

        public int X
        {
            get { return _xCoord; }
            set { _xCoord = value; }
        }

        public int Y
        {
            get { return _yCoord; }
            set { _yCoord = value; }
        }
    }

    public class NewPoint : Point
    {
        private int _zCoord;

        public int Z
        {
            get { return _zCoord; }
            set
            {
                // Don't accept negative Z values
                if (value >= 0)
                {
                    _zCoord = value;
                } 
            }
        }
    }
}


KeepAttributesHorizontal - Lesson 5 Completed
Strictness difference:
VB = implicit cast from Entity to AttributeReference:
Dim attRef As AttributeReference = entity
C# = explicit cast from Entity to AttributeReference
AttributeReference attRef = (AttributeReference)entity;

Array size initialisation difference:
VB = upper  bound
ReDim objIds(attRefColl.Count)
attRefColl.CopyTo(objIds, 0)
ReDim Preserve objIds(attRefColl.Count - 1)
C# = number of items
ObjectId[] objIds = new ObjectId[attRefColl.Count + 1];
attRefColl.CopyTo(objIds, 0);
System.Array.Resize(ref objIds, attRefColl.Count);

Imports Autodesk.AutoCAD.Runtime
Imports Autodesk.AutoCAD.DatabaseServices
Imports Autodesk.AutoCAD.Geometry
Imports Autodesk.AutoCAD.ApplicationServices
Imports Autodesk.AutoCAD.EditorInput


Namespace HorizontalAttributes

    Public Class Commands

        ' Class variable to store the instance of our overrule
        Private Shared myOverrule As KeepStraightOverrule

        <CommandMethod("KeepStraight")>
        Public Shared Sub ImplementOverrule()

            Dim doc As Document =
                    Application.DocumentManager.MdiActiveDocument
            Dim ed As Editor = doc.Editor

            ' Select a block reference

            Dim opts As New PromptEntityOptions(
              vbLf & "Select a block reference:")
            opts.SetRejectMessage(vbLf & "Must be block reference...")
            opts.AddAllowedClass(GetType(BlockReference), True)

            Dim res As PromptEntityResult = ed.GetEntity(opts)

            If res.Status <> PromptStatus.OK Then
                Exit Sub
            End If

            Dim objIds() As ObjectId
            Dim db As Database = doc.Database
            Using trans As Transaction =
                  db.TransactionManager.StartTransaction

                ' Open the BlockReference for read.
                ' We know its a BlockReference because we set a filter in
                '  our PromptEntityOptions
                Dim blkRef As BlockReference =
                        trans.GetObject(res.ObjectId, OpenMode.ForRead)
                ' Record the ObjectIds of all AttributeReferences
                '  attached to the BlockReference.
                Dim attRefColl As AttributeCollection =
                                                  blkRef.AttributeCollection
                ReDim objIds(attRefColl.Count)
                attRefColl.CopyTo(objIds, 0)
                ReDim Preserve objIds(attRefColl.Count - 1)
            End Using

            'We only want to create our overrule instance once,
            ' so we check if it already exists before we create it
            ' (i.e. this may be the 2nd time we've run the command)
            If myOverrule Is Nothing Then
                'Instantiate our overrule class
                myOverrule = New KeepStraightOverrule
                'Register the overrule
                Overrule.AddOverrule(
                  RXClass.GetClass(GetType(AttributeReference)),
                  myOverrule, False)
            End If

            'Specify which Attributes will be overruled
            myOverrule.SetIdFilter(objIds)

            'Make sure overruling is turned on so our overrule works
            Overrule.Overruling = True

        End Sub
    End Class

    'Our custom overrule class derived from TransformOverrule
    Public Class KeepStraightOverrule
        Inherits TransformOverrule

        'We want to change how an AttributeReference responds to being
        ' transformed (moved, rotated, etc.), so we override its
        ' standard TransformBy function.
        Public Overrides Sub TransformBy(ByVal entity As Entity,
                                         ByVal transform As Matrix3d)

            'Call the normal TransformBy function for the attribute
            ' reference we're overruling.
            MyBase.TransformBy(entity, transform)
            'We know entity must be an AttributeReference because
            ' that is the only entity we registered the overrule for.
            Dim attRef As AttributeReference = entity
            'Set rotation of attribute reference to 0 (horizontal)
            attRef.Rotation = 0.0

        End Sub
    End Class
End Namespace


KeepAttributesHorizontal - Lesson 6 Completed

using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;

namespace KeepAttributesHorizontalCs
{
    public class Commands
    {
        // Class variable to store the instance of our overrule
        private static KeepStraightOverrule _overrule;
        // Registered Application Id for Xdata
        private const string _regAppName = "ADSK_ATTRIBUTE_ZERO_OVERRULE";

        [CommandMethod("KeepStraight")]
        public static void ImplementOverrule()
        {
            Document doc = Application.DocumentManager.MdiActiveDocument;
            Editor ed = doc.Editor;

            // Select a block reference

            PromptEntityOptions opts = new PromptEntityOptions("\nSelect a block reference: ");
            opts.SetRejectMessage("\nMust be block reference...");
            opts.AddAllowedClass(typeof(BlockReference), true);

            PromptEntityResult res = ed.GetEntity(opts);

            if (res.Status != PromptStatus.OK)
                return;

            Database db = doc.Database;

            AddRegAppId(db);

            using (Transaction trans = db.TransactionManager.StartTransaction())
            {
                // Open the BlockReference for read.
                // We know its a BlockReference because we set a filter in
                // our PromptEntityOptions.
                BlockReference blkRef =
                    (BlockReference)trans.GetObject(res.ObjectId, OpenMode.ForRead);
                // Record the ObjectIds of all AttributeReferences
                // attached to the BlockReference.
                AttributeCollection attRefColl = blkRef.AttributeCollection;

                // Iterate through  ObjectIds of all AttributeReferences
                // attached to the BlockReference, opening each
                // AttributeReference and adding xdata to it.
                foreach (ObjectId objId in attRefColl)
                {
                    AttributeReference attRef =
                        (AttributeReference)trans.GetObject(objId, OpenMode.ForWrite);
                    // Create new xdata containing the overrule filter name
                    using (ResultBuffer resBuf = new ResultBuffer(
                        new TypedValue((int)DxfCode.ExtendedDataRegAppName, _regAppName),
                        new TypedValue((int)DxfCode.ExtendedDataAsciiString, "Dummy text")))
                    {
                        // Add the xdata
                        attRef.XData = resBuf;
                    }
                }
                trans.Commit();
            }
            // Create and register our overrule and turn overruling on.
            ActivateOverrule();
        }

        [CommandMethod("DontKeepStraight")]
        public static void RemoveXdata()
        {
            Document doc = Application.DocumentManager.MdiActiveDocument;
            Editor ed = doc.Editor;

            // Select a block reference

            PromptEntityOptions opts = new PromptEntityOptions("\nSelect a block reference: ");
            opts.SetRejectMessage("\nMust be block reference...");
            opts.AddAllowedClass(typeof(BlockReference), true);

            PromptEntityResult res = ed.GetEntity(opts);

            if (res.Status != PromptStatus.OK)
                return;

            Database db = doc.Database;

            AddRegAppId(db);

            using (Transaction trans = db.TransactionManager.StartTransaction())
            {
                // Open the BlockReference for read.
                // We know its a BlockReference because we set a filter in
                // our PromptEntityOptions.
                BlockReference blkRef =
                    (BlockReference)trans.GetObject(res.ObjectId, OpenMode.ForRead);
                // Record the ObjectIds of all AttributeReferences
                // attached to the BlockReference.
                AttributeCollection attRefColl = blkRef.AttributeCollection;

                // Iterate through  ObjectIds of all AttributeReferences
                // attached to the BlockReference, opening each
                // AttributeReference and adding xdata to it.
                foreach (ObjectId objId in attRefColl)
                {
                    AttributeReference attRef =
                        (AttributeReference)trans.GetObject(objId, OpenMode.ForWrite);
                    // Create new xdata containing the overrule filter name
                    using (ResultBuffer resBuf = new ResultBuffer(
                        new TypedValue((int)DxfCode.ExtendedDataRegAppName, _regAppName)))
                    {
                        // Add the xdata
                        // Because we leave this blank except for the regappid,
                        // it erases any Xdata we previously added.
                        attRef.XData = resBuf;
                    }
                }
                trans.Commit();
            }
        }

        [CommandMethod("ActivateOverrule")]
        private static void ActivateOverrule()
        {
            // We only want to create our overrule instance once,
            // so we check if it already exists before we create it
            // (i.e. this may be the 2nd time we've run the command)
            if (_overrule == null)
            {
                // Instantiate our overrule class
                _overrule = new KeepStraightOverrule();
                // Register the overrule
                Overrule.AddOverrule
                    (RXClass.GetClass(typeof(AttributeReference)),
                    _overrule, false);
            }
            // Specify which Attributes will be overruled
            _overrule.SetXDataFilter(_regAppName);
            // Make sure overruling is turned on so our overrule works
            Overrule.Overruling = true;
        }

        private static void AddRegAppId(Database db)
        {
            using (Transaction trans = db.TransactionManager.StartTransaction())
            {
                // First create our RegAppId (if it doesn't already exist)
                RegAppTable appTbl =
                    (RegAppTable)trans.GetObject(db.RegAppTableId, OpenMode.ForRead);

                if (!appTbl.Has(_regAppName))
                {
                    RegAppTableRecord appTblRec = new RegAppTableRecord();
                    appTblRec.Name = _regAppName;
                    appTbl.UpgradeOpen();
                    appTbl.Add(appTblRec);
                    trans.AddNewlyCreatedDBObject(appTblRec, true);
                }
                trans.Commit();
            }
        }
    }

    // Our custom overrule class derived from TransformOverrule
    public class KeepStraightOverrule : TransformOverrule
    {
        // We want to change how an AttributeReference responds to being
        // transformed (moved, rotated, etc.), so we override its
        // standard TransformBy function.
        public override void TransformBy(Entity entity, Matrix3d transform)
        {
            // Call the normal TransformBy function for the attribute
            // reference we're overruling.
            base.TransformBy(entity, transform);
            // We know entity must be an AttributeReference because
            // that is the only entity we registered the overrule for.
            AttributeReference attRef = (AttributeReference)entity;
            // Set rotation of attribute reference to 0 (horizontal)
            attRef.Rotation = 0.0;
        }
    }
}


Thanks Gille, did you used an automatic conversion tool?

I updated the code of the 'Bonus Plugin'.
I re-write the the matrix calculation in the BillboardAttributesOverrule.ViewportDraw() method so that it works whatever the block insertion plane.

From Stephen Preston announcement at TheSwamp:

The My First AutoCAD Plugin tutorial is now out of Beta, which means we've added the missing videos and fixed a few bugs. You'll find the tutorial here: http://www.autodesk.com/myfirstautocadplugin. And you can watch a (slightly tongue-in-cheek) promo video here: http://www.youtube.com/watch?v=5a50QULamuU.