AutoCAD DevBlog

Set origin while creating a hatch using .NET

By Deepak Nadig

We had an issue raised by a customer regarding setting origin(image) during hatch creation.

It was found that origin of hatch has to be set in a transaction other than the one in which it is created for it to work correctly.
Below code can be used for testing : 

[CommandMethod("setOrginHatch")]
public void setOriginHatch()
{
    Document doc = Application.DocumentManager.MdiActiveDocument;
    Database db = doc.Database;
    Editor ed = doc.Editor;

    ObjectId mHatchId;
    Hatch mHatch = new Hatch();
    using (Transaction tr1 = db.TransactionManager.StartTransaction())
    {
        BlockTable bt = (BlockTable)tr1.GetObject(doc.Database.BlockTableId, OpenMode.ForRead);
        BlockTableRecord btr = (BlockTableRecord)tr1.GetObject(db.CurrentSpaceId, OpenMode.ForWrite);

        Point2d pt = new Point2d(0, 0);
        Polyline mPolyline = new Polyline(4);
        mPolyline.AddVertexAt(0, pt, 0.0, -1.0, -1.0);
        mPolyline.Normal = Vector3d.ZAxis;
        mPolyline.AddVertexAt(1, new Point2d(pt.X + 10, pt.Y), 0.0, -1.0, -1.0);
        mPolyline.AddVertexAt(2, new Point2d(pt.X + 10, pt.Y + 5), 0.0, -1.0, -1.0);
        mPolyline.AddVertexAt(3, new Point2d(pt.X, pt.Y + 5), 0.0, -1.0, -1.0);
        mPolyline.Closed = true;

        ObjectId mPlineId;
        mPlineId = btr.AppendEntity(mPolyline);
        tr1.AddNewlyCreatedDBObject(mPolyline, true);

        ObjectIdCollection ObjIds = new ObjectIdCollection();
        ObjIds.Add(mPlineId);

        Vector3d normal = new Vector3d(0.0, 0.0, 1.0);
        mHatch.Normal = normal;
        mHatch.Elevation = 0.0;
        mHatch.PatternScale = 2.0;
        mHatch.SetHatchPattern(HatchPatternType.PreDefined, "NET");
        mHatch.ColorIndex = 1;
        mHatch.PatternAngle = 2;

        //trying to set origin here does not work 
        //Point2d setOrigin = new Point2d(6.698, 2.78);
        //mHatch.Origin = setOrigin;

        btr.AppendEntity(mHatch);
        tr1.AddNewlyCreatedDBObject(mHatch, true);

        mHatch.Associative = true;
        mHatch.AppendLoop(HatchLoopTypes.Outermost, ObjIds);
        mHatch.EvaluateHatch(true);

        //get the ObjectId of hatch 
        mHatchId = mHatch.ObjectId;

        tr1.Commit();
    }
    //to set the origin use another transaction 
    using (Transaction tr2 = doc.TransactionManager.StartTransaction())
    {
        Entity ent = (Entity)tr2.GetObject(mHatchId, OpenMode.ForWrite);
        if (ent != null)
        {
            Hatch nHatch = ent as Hatch;
            String hatchName = nHatch.PatternName;
            Point2d setOrigin = new Point2d(6.698, 2.78);
            nHatch.Origin = setOrigin;
            nHatch.SetHatchPattern(HatchPatternType.PreDefined, hatchName);
            nHatch.EvaluateHatch(true);
            nHatch.Draw();
        }
        tr2.Commit();
    }
}

Running OEMMAKEWIZARD from Command Line

By Madhukar Moogala

This is small batch script may be useful for OEM Developers.

Once you have created your project, you can run the AutoCAD OEM Make Wizard from the command line to automate building your product. In this mode, you can use any of the build options available on the Build Your Product page of the AutoCAD OEM Make Wizard. Enter the following command to display a Help screen describing the command-line options for the AutoCAD OEM Make Wizard:

oemmakewizard /? 

Build Options:

Path Options  
   /PA:  Specifies the path for AutoCAD OEM location  
   /PB:  Specifies the path for bitmap location  
Import Options  
   /IC:  Specifies a file for enabling\disabling AutoCAD commands  
   /IAS:  Specifies a file for adding your commands  
   /IRS:  Specifies a file that allows you to remove user specified commands or setvars  
Build Options  
   /BALL  Builds all (does not include the files executed by /BT command)  
   /BA  Binds ObjectARX/Core ObjectARX applications  
   /BB  Binds managed applications  
   /BBA  Binds managed ObjectARX applications  
   /BL  Binds AutoLISP applications  
   /BD  Binds DLL modules  
   /BV  Bind DVB macros  
   /BC  Copies files  
   /BT  Builds type libraries and registry files  
   /BT+  Registers associated registry files  
   /BI  Change icons  
   /BR  Rebuilds resources  
   /BR+  Rebuilds resources and uses settings with AutoCAD OEM  
   /BR-  Rebuilds resources, but does not bind the DLLs  
   /STOP  Interrupts batch mode when errors are encountered  
   /?  Displays the Help screen for all command options

Viewing LineType Appearance

By Madhukar Moogala

I have recieved this query, user would like to get appearance of LineTypeRecord or LineTypes through API.

We can use Comments API to gets the Linetype appearance in the form of ascii string.

Code:

public static void LineTypeAppearance()
        {
            Database database = HostApplicationServices.WorkingDatabase;
            var ed = AcCore.Application.DocumentManager.MdiActiveDocument.Editor;
            using (Transaction t = database.TransactionManager.StartTransaction())
            {
                var symTable = (SymbolTable)t.GetObject(database.LinetypeTableId,
                                                        OpenMode.ForRead);
                foreach (ObjectId id in symTable)
                {
                    var symbol = (LinetypeTableRecord)t.GetObject(id, OpenMode.ForRead);
                    ed.WriteMessage(string.Format("\nName: {0}\t Appearance: {1}",
                                                    symbol.Name, symbol.Comments));
                }

                t.Commit();
            }
        }

Output

Name: BYBLOCK   Desc:
Name: BYLAYER   Desc:
Name: CONTINUOUS      Desc: Solid line
Name: Wall Base|CENTER     Desc: Center ____ _ ____ _ ____ _ ____ _ ____ _ ____
Name: Wall Base|DASHED     Desc: Dashed __ __ __ __ __ __ __ __ __ __ __ __ __ _

Determine the radius and center of circular cone base using .NET

By Deepak Nadig

We can make use of Brep support to determine the radius and center of a cone( properties shown up in  the image image) with circular base.    

 Below .NET code snippet can be used : 

[CommandMethod("circularConeRadiusAndCenter")]
public void circularConeRadiusAndCenter()
{
    Document doc = Autodesk.AutoCAD.ApplicationServices.Application.DocumentManager.MdiActiveDocument;
    Database db = doc.Database;
    Editor ed = doc.Editor;

    // Ask the user to select a solid
    PromptEntityOptions peo = new PromptEntityOptions("Select a 3D solid");
    peo.SetRejectMessage("\nA 3D solid must be selected.");
    peo.AddAllowedClass(typeof(Solid3d), true);
    PromptEntityResult per = ed.GetEntity(peo);

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

    Transaction tr = db.TransactionManager.StartTransaction();
    using (tr)
    {
        Solid3d sol = tr.GetObject(per.ObjectId, OpenMode.ForRead) as Solid3d;
        using (Brep brep = new Brep(sol))
        {
            //check if base is a circular. If yes, then determine the center and radius
            foreach (Complex cmp in brep.Complexes)
            {
                int edgeCnt = 1;
                foreach (Edge edge in brep.Edges)
                {
                    ed.WriteMessage("\n --> Edge : {0}", edgeCnt++);
                    Curve3d edgeCurve = edge.Curve;
                    if (edgeCurve is ExternalCurve3d)
                    {
                        ed.WriteMessage("\n Edge type : {0}", "ExternalCurve3d");
                        ExternalCurve3d extCurve3d = edgeCurve as ExternalCurve3d;
                        Curve3d nativeCurve = extCurve3d.NativeCurve;
                        if (nativeCurve is CircularArc3d)
                        {
                            ed.WriteMessage("\n Native curve type : {0}", "CircularArc3d");
                            CircularArc3d circArc3d = nativeCurve as CircularArc3d;
                            ed.WriteMessage("\n radius is " + circArc3d.Radius.ToString());                                    
                            ed.WriteMessage("\n center is " + PointToStr(circArc3d.Center));
                        }
                        else
                        {
                            ed.WriteMessage("\n Native curve type of cone is not Circular");
                            return;
                        }

                    }

                }
            }
        }
    }
}
private string PointToStr(Point3d point)
{
    return "[" +
        point.X.ToString("F2") + ", " +
        point.Y.ToString("F2") + ", " +
        point.Z.ToString("F2")
        + "]";
}

Forge NextGen webinars!

Are you ready to learn about the new technologies that will become available on the Forge platform? 
Then you should not miss these webinars :)

Date : 26th April 2018
Time : 8.00 AM PST
Duration : 90 minutes
Title : The Future of Making Things on Forge: Sneak Peek at Forge NextGen (HFDM & App Framework)
Registration Link: https://attendee.gotowebinar.com/register/8209398405782333955
Presenter:  Lior Gerling, Sr. Product Manager Forge Platform
 
Date : May 9th 2018
Time : 8.00 AM PST
Duration : 90 minutes
Title : A technical introduction to Forge High Frequency Data Management (HFDM) SDK and Forge App Framework
Registration Link: https://attendee.gotowebinar.com/register/3624195224359611394  
Presenter:  Kai Schroeder, Engineering Manager, Forge Platform

AutoCAD 2019 ObjectARX and .NET wizards

By Deepak Nadig

We have had many users asking for new versions of wizards that are Visual Studio 2017 compatible to work with AutoCAD 2019. Here they are  : 

AutoCAD ObjectARX 2019 Wizard 

AutoCAD .NET 2019 Wizard

P.S:
We will soon have these wizards downloadable from the Tools section of https://www.autodesk.com/developer-network/platform-technologies/autocad

RealDWG: Implementation of dumpAcDbSubDMesh

By Madhukar Moogala

In RealDWG dumpDWG sample project [RealDWG 2018\Samples\DumpDWG], dumpAcDbSubDMesh implementation is missing, I received a query from a ADN partner, so for the benefit of every one I blogging this.

Context: If input drawing to your RealDWG app contains Mesh elements, and you would like to view this elements in any other 3d viewer for example, OpenGL, this implementation will come handy.

void dumpAcDbSubDMesh(AcDbEntity *pEnt)
{
entInfo(pEnt, sizeof(AcDbSubDMesh));
if (pEnt->isKindOf(AcDbSubDMesh::desc())) 
{
	entInfo(pEnt, sizeof(AcDbSubDMesh));
	AcDbSubDMesh *pMesh = AcDbSubDMesh::cast(pEnt);
	Adesk::Int32  nFaces, 
					nEdges, 
					nVertices,
					nSubFaces,
					nSubVertices,
					nSubdLevel;
	bool bWaterTight;
	Acad::ErrorStatus es = pMesh->numOfFaces(nFaces);
	es = pMesh->numOfVertices(nVertices);
	AcGePoint3d pt;
	// this is just for simplicity instead of 
	//traversing all the vertices. 
	//if the vertices > 50 it increments by that number fold.
	int increment = nVertices / 50;
	if (!increment)increment++;
	for (int i = 0; igetVertexAt(i, pt);
		_print(_T("\t\t Vertex Points[%d] %g,%g,%g\n"), i,
			pt.x, pt.y, pt.z);
	}

	es = pMesh->numOfSubDividedFaces(nSubFaces);
	es = pMesh->numOfSubDividedVertices(nSubVertices);
	es = pMesh->isWatertight(bWaterTight);
	es = pMesh->subdLevel(nSubdLevel);
	es = pMesh->numOfEdges(nEdges);
	
	AcGePoint3dArray nsubVerticesArray;
	es = pMesh->getSubDividedVertices(nsubVerticesArray);

	AcArray nsubfacesArray;
	es = pMesh->getSubDividedFaceArray(nsubfacesArray);
	// The content of the faces list is like so :
	// [number of vertices of next face],
	// ,
	// e.g. [4], <1, 2, 3, 4>, [3], <1, 2, 3>, etc


	for (int numVertices = 0, 
		i = 0; 
		i < nsubfacesArray.length();
		i += numVertices + 1)
	{
	numVertices = nsubfacesArray.at(i);
	// Let's print the edges of the face
	_print(_T("\t SubDMesh Edge Points \n"));
	_print(_T("\t\t Face vertex Points[%d] \n"), numVertices);						
	for (int j = 0; j < numVertices; j++)
	{
		AcGePoint3d startPt = 
		nsubVerticesArray.at(nsubfacesArray.at(i + j + 1));
		AcGePoint3d endPt =
		nsubVerticesArray.at(nsubfacesArray.at(i + ((j + 1) % numVertices) + 1));							
		_print(_T("\t\t Vertex Points[%d] [{%g,%g,%g} ,{ %g,%g,%g }]\n"), j,
			startPt.x, startPt.y, startPt.z , endPt.x, endPt.y, endPt.z);
		//Now you can draw lines using these points in OpenGl

	}
	}
}
}

Sample Output

SubDMesh Edge Points
                 Face vertex Points[4]
                 Vertex Points[0] [{10.1735,8.28866,16.5088} ,{ 16.5135,8.28866,16.5088 }]
                 Vertex Points[1] [{16.5135,8.28866,16.5088} ,{ 16.5135,11.4619,16.5088 }]
                 Vertex Points[2] [{16.5135,11.4619,16.5088} ,{ 10.1735,11.4619,16.5088 }]
                 Vertex Points[3] [{10.1735,11.4619,16.5088} ,{ 10.1735,8.28866,16.5088 }]
         SubDMesh Edge Points
                 Face vertex Points[4]
                 Vertex Points[0] [{10.1735,5.11544,16.5088} ,{ 16.5135,5.11544,16.5088 }]
                 Vertex Points[1] [{16.5135,5.11544,16.5088} ,{ 16.5135,8.28866,16.5088 }]
                 Vertex Points[2] [{16.5135,8.28866,16.5088} ,{ 10.1735,8.28866,16.5088 }]
                 Vertex Points[3] [{10.1735,8.28866,16.5088} ,{ 10.1735,5.11544,16.5088 }]
         SubDMesh Edge Points
                 Face vertex Points[4]
                 Vertex Points[0] [{10.1735,1.94223,16.5088} ,{ 16.5135,1.94223,16.5088 }]
                 Vertex Points[1] [{16.5135,1.94223,16.5088} ,{ 16.5135,5.11544,16.5088 }]
                 Vertex Points[2] [{16.5135,5.11544,16.5088} ,{ 10.1735,5.11544,16.5088 }]
                 Vertex Points[3] [{10.1735,5.11544,16.5088} ,{ 10.1735,1.94223,16.5088 }]
         SubDMesh Edge Points
                 Face vertex Points[4]
                 Vertex Points[0] [{16.5135,8.28866,16.5088} ,{ 22.8534,8.28866,16.5088 }]
                 Vertex Points[1] [{22.8534,8.28866,16.5088} ,{ 22.8534,11.4619,16.5088 }]
                 Vertex Points[2] [{22.8534,11.4619,16.5088} ,{ 16.5135,11.4619,16.5088 }]
                 Vertex Points[3] [{16.5135,11.4619,16.5088} ,{ 16.5135,8.28866,16.5088 }]
         SubDMesh Edge Points
                 Face vertex Points[4]
                 Vertex Points[0] [{16.5135,5.11544,16.5088} ,{ 22.8534,5.11544,16.5088 }]
                 Vertex Points[1] [{22.8534,5.11544,16.5088} ,{ 22.8534,8.28866,16.5088 }]
                 Vertex Points[2] [{22.8534,8.28866,16.5088} ,{ 16.5135,8.28866,16.5088 }]
                 Vertex Points[3] [{16.5135,8.28866,16.5088} ,{ 16.5135,5.11544,16.5088 }]
         SubDMesh Edge Points
                 Face vertex Points[4]
                 Vertex Points[0] [{16.5135,1.94223,16.5088} ,{ 22.8534,1.94223,16.5088 }]
                 Vertex Points[1] [{22.8534,1.94223,16.5088} ,{ 22.8534,5.11544,16.5088 }]
                 Vertex Points[2] [{22.8534,5.11544,16.5088} ,{ 16.5135,5.11544,16.5088 }]
                 Vertex Points[3] [{16.5135,5.11544,16.5088} ,{ 16.5135,1.94223,16.5088 }]
         SubDMesh Edge Points
                 Face vertex Points[4]
                 Vertex Points[0] [{22.8534,8.28866,16.5088} ,{ 29.1934,8.28866,16.5088 }]
                 Vertex Points[1] [{29.1934,8.28866,16.5088} ,{ 29.1934,11.4619,16.5088 }]
                 Vertex Points[2] [{29.1934,11.4619,16.5088} ,{ 22.8534,11.4619,16.5088 }]
                 Vertex Points[3] [{22.8534,11.4619,16.5088} ,{ 22.8534,8.28866,16.5088 }]
         SubDMesh Edge Points
                 Face vertex Points[4]
                 Vertex Points[0] [{22.8534,5.11544,16.5088} ,{ 29.1934,5.11544,16.5088 }]
                 Vertex Points[1] [{29.1934,5.11544,16.5088} ,{ 29.1934,8.28866,16.5088 }]
                 Vertex Points[2] [{29.1934,8.28866,16.5088} ,{ 22.8534,8.28866,16.5088 }]
                 Vertex Points[3] [{22.8534,8.28866,16.5088} ,{ 22.8534,5.11544,16.5088 }]
         SubDMesh Edge Points
                 Face vertex Points[4]
                 Vertex Points[0] [{22.8534,1.94223,16.5088} ,{ 29.1934,1.94223,16.5088 }]
                 Vertex Points[1] [{29.1934,1.94223,16.5088} ,{ 29.1934,5.11544,16.5088 }]
                 Vertex Points[2] [{29.1934,5.11544,16.5088} ,{ 22.8534,5.11544,16.5088 }]
                 Vertex Points[3] [{22.8534,5.11544,16.5088} ,{ 22.8534,1.94223,16.5088 }]

AcCoreConsole: Explode DBText To Geometry

By Madhukar Moogala

I received a query from one of our Technical Sales Specialist whose customer would like to automate a design workflow using Forge Design Automation one aspect of work flow is to explode Text objects in to Geometry [polylines and arcs].

We have an existing express tool called TXTEXP, unfortunately this tool is not available for Forge or AcCoreConsole, I created a simple C# program which explodes a text object in to geometry, this custom program can be used as custom command in AcCoreConsole.

public void EXPTXT()
{
    var doc = Application.DocumentManager.MdiActiveDocument;
    var db = doc.Database;
    var ed = doc.Editor;
    // selection text
    ObjectId[] dbtextIds = ed.SelectTextEntitesInModelSpace();
    foreach (ObjectId id in dbtextIds)
    {
        using (Transaction tr = db.TransactionManager.StartTransaction())
        {
            var text = (DBText)tr.GetObject(id, OpenMode.ForWrite);
            ObjectId[] ids = new ObjectId[1];
            ids[0] = id;
            ed.SetImpliedSelection(ids);
            var tempFile = Path.Combine(Path.GetTempPath(), "Q.wmf");

            if (File.Exists(tempFile))
            {
                File.Delete(tempFile);
            }
            ed.Command("_.WMFOUT", tempFile, "", "");
            var viewSize = (double)Application.GetSystemVariable("VIEWSIZE");
            var screenSize = (Point2d)Application.GetSystemVariable("SCREENSIZE");
            double factor = viewSize * (screenSize.X / screenSize.Y);
            var viewCtr = (Point3d)Application.GetSystemVariable("VIEWCTR");
            //Transform viewCtr from UCS to DCS
            Matrix3d matUCS2DCS = ed.UCS2WCS() * ed.WCS2DCS();
            viewCtr = viewCtr.TransformBy(matUCS2DCS);
            var p1 = new Point3d(viewCtr.X - (factor / 2.0), 
                                 viewCtr.Y - (viewSize / 2.0), .0);
            var p2 = new Point3d(viewCtr.X + (factor / 2.0),
                                viewCtr.Y + (viewSize / 2.0), .0);
            //Transorm p1,p2 from DCS to UCS;
            Matrix3d matDCS2UCS = ed.DCS2WCS() * ed.WCS2UCS();
            p1 = p1.TransformBy(matDCS2UCS);
            p2 = p2.TransformBy(matDCS2UCS);
            Point2d wmfinBlockPos = new Point2d(p1.X, p2.Y);
            var tempWithOutExt = Path.Combine(Path.GetDirectoryName(tempFile),
                                 Path.GetFileNameWithoutExtension(tempFile));
            ed.Command("_.WMFIN", tempWithOutExt, wmfinBlockPos, "2", "", "");
            try
            {
                var wmfBlock = tr.GetObject(ed.SelectLastEnt(), OpenMode.ForWrite) as BlockReference;
                DBObjectCollection pElems = new DBObjectCollection();
                wmfBlock?.Explode(pElems);
                var space = (BlockTableRecord)tr.GetObject(db.CurrentSpaceId, OpenMode.ForWrite);
                foreach (DBObject elem in pElems)
                {
                    space.AppendEntity(elem as Entity);
                    tr.AddNewlyCreatedDBObject(elem, true);
                }
                //Purge unused WMFIN Block and reference
                ObjectId wmfBtr = GetNonErasedTableRecordId(db.BlockTableId, wmfBlock.Name);
                ObjectIdCollection blockIds = new ObjectIdCollection();
                blockIds.Add(wmfBtr);
                db.Purge(blockIds);
                foreach (ObjectId oId in blockIds)
                {
                    DBObject obj = tr.GetObject(oId, OpenMode.ForWrite);
                    obj.Erase();

                }
            }
            catch (Exception ex)
            {
                ed.WriteMessage(ex.Message);
            }
            finally
            {
                //Erase text entity
                text.Erase();
                tr.Commit();
            }
        }

    }

}

source:

Explode-Text-To-Geomety

Preview In Action

Entitlement: How To Display Autodesk Sign In Dialog

By Madhukar Moogala

This is a small post which will be useful by App publishers, in case if user is not logged, app developers can display Autodesk Sign In Dialog.

bool bIsUserLoggedIn = true;
#define CONNECTTOWEB _T("CONNECTWEBSERVICES")
void onlineUI()
{
	//if user isn't logged, onlineuserid will be empty
	struct resbuf rb;
	acedGetVar(_T("ONLINEUSERID"), &rb);
	if (rb.resval.rstring != NULL) {

		CString userId(rb.resval.rstring);
		if (userId.IsEmpty()) bIsUserLoggedIn = false;
		// Release memory acquired for string:
		free(rb.resval.rstring);
	}
	// pop once only
	if (!bIsUserLoggedIn) {
		// prompt user to login
		// ensure unload-able from ui
		acrxLoadModule(_T("AcConnectWebServices.arx"), false, true);
		acrxLoadModule(_T("AcConnectWebServices.arx"), false, false);

		ASSERT(acrxServiceIsRegistered(CONNECTTOWEB));
		if (acrxServiceIsRegistered(CONNECTTOWEB))
		{
			typedef void(*ADSKLOGIN) ();
			ADSKLOGIN pAdskLogin = (ADSKLOGIN)
				acrxDynamicLinker->getSymbolAddress(CONNECTTOWEB,
					_T("AcConnectWebServicesLogin"));
			ASSERT(pAdskLogin);
			if (pAdskLogin != NULL)
				pAdskLogin();
		}
		acrxUnloadModule(_T("AcConnectWebServices.arx"), false);
	}

}

namespace MgdOnlineUI
{
    public class WebUtils
    {
        [DllImport("AcConnectWebServices.arx", EntryPoint = "AcConnectWebServicesLogin")]
            public static extern bool AcConnectWebServicesLogin();
    }
    public class Class1
    {
        [CommandMethod("ONLINEUI")]
        public void Onlineui()
        {
            //If ONLINEUSERID is empty or null, user is not logged in to system.
            if(String.IsNullOrEmpty((string)Application.GetSystemVariable("ONLINEUSERID")))
            {
                WebUtils.AcConnectWebServicesLogin();
            }
        }
    }
}

Set ColumnType of MText on creation of MText Object

By Deepak Nadig

We recently had a query regarding eNotApplicable runtime exception thrown trying to set ColumnType when MText is created as in the snippet: 

MText mytext = new MText();
mytext.SetDatabaseDefaults();
mytext.Contents = "mytext";
mytext.Layer = "0";
mytext.ColorIndex = 3;
mytext.Location = new Point3d(0.0, 0.0, 0.0);
mytext.ColumnType = ColumnType.NoColumns;

To avoid this exception it is required to set MText.Width value greater than 0.0 before setting the ColumnType. Below command sets ColumnType 

[CommandMethod("TESTMTEXT")]
public static void testMtext()
{
    Document doc = Autodesk.AutoCAD.ApplicationServices.Core.Application.DocumentManager.MdiActiveDocument;
    if (doc == null)
        return;
    try
    {
        using (Transaction tr = doc.TransactionManager.StartTransaction())
        {
            MText mytext = new MText();
            mytext.SetDatabaseDefaults();
            mytext.Contents = "mytext";
            mytext.Layer = "0";
            mytext.ColorIndex = 3;
            mytext.Location = new Point3d(0.0, 0.0, 0.0);
            mytext.Width = 0.0; // don't forget me 
            if(mytext.Width > 0.0)
            mytext.ColumnType = ColumnType.NoColumns;

            BlockTable bt = (BlockTable)tr.GetObject(doc.Database.BlockTableId, OpenMode.ForRead);
            BlockTableRecord btr = (BlockTableRecord)tr.GetObject(bt[BlockTableRecord.ModelSpace], OpenMode.ForWrite);
            btr.AppendEntity(mytext);
            tr.AddNewlyCreatedDBObject(mytext, true);
            tr.Commit();
        }
    }
    catch (System.Exception ex)
    {
        doc.Editor.WriteMessage("\nError: " + ex.ToString());
    }
}

It is notable that trying to change ColumnType of selected MText without setting Defined width value above 0.0 is not possible in UI :