polygons

I want to make a block of a triangle using vb.net

I know my geometry to be a 3 sided polygon circumscribed about a 3,5 rasdius circle but I can't find the polygon object. Does it exist in VB.Net?

I know I can construct my triangle in other ways but I thought a polygon would be easier.

Dave, are you doing this in VB or C#?

Have a look in your Jerry Winters book Chapter 14. He deals with drawing polygons there.

Basically you have a function that takes a centre point, the number of sides and the radius and then returns the points required to draw polygon. Then use

DatabaseServices.Poly3DType.SimplePoly, PointsIn, True

Hope that helps.

If I am understanding you correctly, you're after either the Polyline2d, or Polyline3d type found under Autodesk.AutoCAD.DatabaseServices in Object Browser.

At last I beat RenderMan to the draw

At last I beat RenderMan to the draw

...

Dave, there are several ways to accomplish this task.

For example, you could register an ObjectAppended, and CommandEnded Event handler, and invoke the POLYGON Command, such that when the ObjectAppended Event is raised, you can store the Polyline* typed object's ObjectId (the one just added to the Database) to an internal Property object, so that when the CommandEnded Event is raised you can then modify said ObjectId.

Also... So that this code is not always processing every Object appended to the Database, you might consider registering a CommandWillStart Event handler, to filter for the POLYGON Command, and conditionally register the ObjectAppended Event handler... Just be mindful to unregister the ObjectAppended Event handler via the CommandCancelled, CommandEnded, or CommandFailed Events (you can use the same Method for all three if you like).

In this manor, only when the user invokes the built-in POLYGON Command is your code 'watching' for Polyline* typed objects being appended to the Database, and programmatically acting on said object once successfully created.

The alternative is to filter each-and-every object appended to the Database for PolyLine* typed objects, but even then, how to distinguish a generic polyline from the polyline created via the POLYGON Command? Just a thought.

Thanks for the answers. One thing I didn't state was that I was just about to leave work until Friday so won't be able t examine answers in detail. To be honest, I didn't expect any answers!

Dave, are you doing this in VB or C#?

 

Have a look in your Jerry Winters book Chapter 14. He deals with drawing polygons there.

 

Basically you have a function that takes a centre point, the number of sides and the radius and then returns the points required to draw polygon. Then use

DatabaseServices.Poly3DType.SimplePoly, PointsIn, True

 

 

Hope that helps.

For when you come back, here's a quickly written, working framework (in C#) for what I've outlined above... In this pseudo-code, I simply change the ColorIndex Property to 1 (Red) for each 'polygon' the user adds to the Database via the POLYGON Command:

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

using acApp = Autodesk.AutoCAD.ApplicationServices.Application;

using System;
using System.IO;
using System.Reflection;

[assembly: ExtensionApplication(typeof(CADTutor.Sample.AllPolygonsRed))]

namespace CADTutor.Sample
{
   class AllPolygonsRed : IExtensionApplication
   {
       #region Properties

       public static ObjectId Polygon { get; internal set; }

       #endregion

       #region Initialization

       void IExtensionApplication.Initialize()
       {
           DocumentCollection acDocs = acApp.DocumentManager;
           Document doc = acDocs.MdiActiveDocument;
           Editor ed = doc.Editor;

           acDocs.DocumentCreated += OnDocumentCreated;
           doc.CommandWillStart += OnCommandWillStart;

           ed.WriteMessage("\n** " + 
               Path.GetFileNameWithoutExtension(Assembly.GetExecutingAssembly().Location) 
               + " loaded ** \n");
       }

       void IExtensionApplication.Terminate()
       {
       }

       #endregion

       #region Methods

       public static void OnCommandEnded(object sender, CommandEventArgs e)
       {
           Document doc = acApp.DocumentManager.MdiActiveDocument;
           Editor ed = doc.Editor;

           UnRegisterEvents(doc);

           try
           {
               using (DocumentLock docLock = doc.LockDocument())
               {
                   using (Transaction trans =
                       doc.Database.TransactionManager.StartOpenCloseTransaction())
                   {
                       if (Polygon != null)
                       {
                           Entity entity =
                                   trans.GetObject(Polygon, OpenMode.ForWrite) as Entity;

                           if (entity != null)
                               entity.ColorIndex = 1;

                           ed.WriteMessage("** Polygon entity color changed to red ** \n");
                       }

                       trans.Commit();
                   }
               }
           }

           catch (System.Exception ex)
           {
               ed.WriteMessage("\nSystem.Exception error: " + ex.Message);
           }
       }

       public static void OnCommandWillStart(object sender, CommandEventArgs e)
       {
           string cmd = e.GlobalCommandName.ToString().ToUpper();

           if (cmd != null && Utils.WcMatch(cmd, "*POLYGON"))
               RegisterEvents(acApp.DocumentManager.MdiActiveDocument);
       }

       public static void OnDocumentCreated(Object sender, DocumentCollectionEventArgs e)
       {
           Document doc = e.Document;

           if (doc != null)
               doc.CommandWillStart += OnCommandWillStart;
       }

       public static void OnObjectAppended(object sender, ObjectEventArgs e)
       {
           ObjectId id = e.DBObject.ObjectId;

           if (id != null)
               Polygon = id;
       }

       public static void RegisterEvents(Document doc)
       {
           if (doc != null)
           {
               Editor ed = doc.Editor;

               // command events
               doc.CommandCancelled += OnCommandEnded;
               doc.CommandEnded += OnCommandEnded;
               doc.CommandFailed += OnCommandEnded;

               // database events
               doc.Database.ObjectAppended += OnObjectAppended;

               ed.WriteMessage("\n** Polygon events registered ** \n");
           }
       }

       public static void UnRegisterEvents(Document doc)
       {
           if (doc != null)
           {
               Editor ed = doc.Editor;

               // command events
               doc.CommandCancelled -= OnCommandEnded;
               doc.CommandEnded -= OnCommandEnded;
               doc.CommandFailed -= OnCommandEnded;

               // database events
               doc.Database.ObjectAppended -= OnObjectAppended;

               ed.WriteMessage("\n** Polygon events unregistered ** \n");
           }
       }

       #endregion
   }
}