N ways to draw small circles in CAD—CAD secondary development guide
N ways to draw small circles in CAD—CAD secondary development guide
Official Account: Non-Deconstructive · Author: Zhou Wenqi (Venchy)
For all drawing dogs who use CAD to draw, just drawing a circle does not seem to be a difficult task.Click the command bar, click the toolbar, and enter the shortcut key directly.。。When seeing this title, the drawing dogs may laugh and say Are you kidding me?！Is this topic worthy of writing a public account?！！
As an editor who is not experienced in drawing dogs, drawing circles with bare hands is of course not a problem.However, does AutoCAD only provide us with such mechanical operations?！Are there areas we haven’t discovered yet that are worth exploring?Today, the editor will use the case of drawing circles to discuss with you the various possibilities of secondary development on AutoCAD.
- LISP
LISP is a general-purpose high-level computer programming language that has long monopolized applications in the field of artificial intelligence.As a language designed for artificial intelligence, LISP is the first declarative functional programming language, which is different from the imperative procedural C, Fortran and object-oriented structured programming languages such as Java and C#. AutoLISP is a LISP programming language developed by Autodesk. LISP is the abbreviation of List Processor.Through autolisp programming, engineers can save a lot of time.AutoLISP language, as an intelligent programming language embedded in AutoCAD, is an indispensable tool for developing and applying AutoCAD. Among them, there are many ways to draw a circle using only the AutoLisp language for secondary development:
(1) COMMAND command
Open the AutoLisp secondary development IDE through tool-》autolisp-》visual lisp editor under the cad interface.A particularly simple programming method provided by Lisp is to use the “command” command.
Under the command command, you only need to serialize your mouse operation process into a string of codes in the CAD interface, and you can complete a series of operations at once.The disadvantage is that only one command can be run at a time. The code for drawing a circle is as follows:
(defun c:cir() (setq point1 (getpoint)) ;define center point of the circle (command “circle” point1 100 "");command )
Save the lisp file and drag it into cad or load it through the netload command. With only two simple lines of code, you can complete the drawing of a circle.
(2) ENTMAKE command
From the perspective of Lisp language, each CAD primitive is a collection of a series of attributes.Such a collection of attributes is defined as an entity group.Each entity group has a string of codes.Let’s read the entity group code for a regular circle:
((-1 . <Entity name: 7ff422e04d60>) (0 . “CIRCLE”) (330 . <Entity name: 7ff422e039f0>) (5 . “266”) (100 . “AcDbEntity”) (67 . 0) (410 . “Model”) (8 . “0”) (100 . “AcDbCircle”) (10 17.5337 30.5646 0.0) (40 . 100.0) (210 0.0 0.0 1.0))
Among them, (0 . “CIRCLE”) represents the entity group as a circle, and (10 17.5337 30.5646 0.0) represents the center of the circle.。。。Just read the relevant instructions to read the meaning of each entity group code.So, can we use related entity groups to generate a circle in CAD?The entmake command can achieve this purpose. The following is the code for drawing a circle using the entmake command:
(defun c:cir() (entmake ’( (0 . “CIRCLE”) ;define circle (62 . 1) ;define color (10 0.0 0.0 0.0) ;define center (40 . 50.0) ; define radius ) ) )
Or load lisp first, enter the command, and you’re done.
(3) Reactor
A reactor is a simple link between AutoCAD and the user’s application, which allows functions to respond to events that occur within AutoCAD.For example, you can create a reactor to notify the user’s application that a primitive has been deleted.At this time, the application will perform some actions to respond to this event.A button on a form is a simple example of an event-driven program that uses events and responses to perform actions.When the button is selected, it activates an event, like a signal or broadcast.The event is detected by the reactor and the resulting action is performed using a process called a callback. Here is the code to draw a circle using the reactor:
(defun c:cir() (setq thisdrawing (vla-get-activedocument (vlax-get-acad-object))) ;get drawing object (setq mspace (vla-get-modelspace thisdrawing));get model space (setq pt1 (vlax-3d-point (getpoint “\nCenter point: ”)));define center of circle (vla-AddCircle mspace pt1 50) ;add circle )
- VBA
Visual Basic for Applications (VBA) is a macro language of Visual Basic, a programming language developed by Microsoft to perform common automation (OLE) tasks in its desktop applications.It can mainly be used to extend the functionality of Windows applications, especially Microsoft Office software.VBA is also the integrated development environment of AutoCAD. The addition of VBA expands AutoCAD’s integrated customization capabilities.The development environment of AutoCAD is also a visual development environment.
But when we try to open the VBA IDE in AutoCAD, it often prompts that there is no related program.This is because since AutoCAD2010, AutoCAD has canceled the VBA IDE interface.If you want to use VBA for secondary development of AutoCAD, you need to install the AutoCAD VBA enabler. The download address is as follows: (1)http://www.autodesk.com/vba-download (2)http://www.cad8.net/thread-12322-1-1.html When the installation is complete, repeat the previous operation or enter vbaide on the cad command line, and the VBA IDE under the cad interface will appear as shown in the figure.
This interface is exactly the same as the VBA interface in Excel. If you feel a little helpless, enter F2, as shown in the figure below, and the paths for various functions of AutoCAD’s VBA secondary development will appear.
The following is the code for drawing a circle in AutoCAD using VBA:
Sub addcir() Dim point1(0 To 2) As Double ‘define point1 Dim cir As AcadCircle ‘define circle object point1(0) = 0 ‘define coordinate of point1 point1(1) = 0 point1(2) = 0 Set cir = ThisDrawing.ModelSpace.AddCircle(point1, 100) End Sub
The following is the drawing process:
You’re done!
- C#.NET
As for the VBA and VLisp mentioned earlier, their advantages and disadvantages are obvious: ObjectArx is powerful and has high programming efficiency, but its disadvantage is that programmers must master VC++, and this language is very difficult to learn; although VBA and VLisp are simple and easy to use, they seem to be incapable of developing large programs.So is there a language that can combine their advantages and try to avoid their shortcomings? The answer is yes, that is Microsoft’s new 21st century programming language C#. C# communicates with AutoCAD through the AutoCAD ActiveX bridge.AutoCAD ActiveX enables users to programmatically operate AutoCAD from within or outside AutoCAD.It does this by displaying AutoCAD objects to the “outside world”.Once these objects are displayed, many different programming languages and environments can access them.Regarding AutoCAD ActiveX, you can refer to the help that comes with AutoCAD.
Regarding C#’s description of AutoCAD secondary development environment: Due to the continuous upgrading of AutoCAD’s development framework, different versions of CAD need to correspond to different versions of the netframework framework, and correspondingly to different Visual Studio.The requirements for each development version are as follows:
The editor’s development environment is Visual Studio 2010 version and AutoCAD 2012. Development process: (1) Create a class library in VS.
(2) Reference CAD internal assemblies, including acdbmgd.dll, acmgd.dll, AcCui.dll and accoremgd.dll, etc.It should be noted that after adding the reference, you need to right-click the reference property and adjust Copy Local to false.
(3) Set the target framework and debugging method.Right click on the selected project and select Properties.Choose the appropriate external program (acad.exe) and the appropriate framework.
The following is the code for drawing a circle using C#.net:
using System; using System.Collections.Generic; using System.Linq; using System.Text; using Autodesk.AutoCAD.DatabaseServices; using Autodesk.AutoCAD.Geometry; using Autodesk.AutoCAD.Runtime;
namespace Autodesk { public class Class1 { [CommandMethod(“Drawcir”)] //Define circle drawing function public void Drawcir() { //Get the current active graphics database Database db = HostApplicationServices.WorkingDatabase; //Define the center of the circle Point3d stPoint = new Point3d(0, 0, 0); //Define circle Circle cir= new Circle(stPoint,Vector3d.ZAxis,100); using (Transaction tr = db.TransactionManager.StartTransaction()) { BlockTable bt = (BlockTable)tr.GetObject(db.BlockTableId, OpenMode.ForRead); BlockTableRecord btr = (BlockTableRecord)tr.GetObject(bt[BlockTableRecord.ModelSpace], OpenMode.ForWrite); //Add the circle to the block table.This method has a return value and can return the id of the entity object btr.AppendEntity(cir); //Add the object to the transaction tr.AddNewlyCreatedDBObject(cir, true); //Submit transaction processing tr.Commit(); } } } }
Special attention needs to be paid to the several pieces of code added in orange. After the code is written, right-click on the project to generate, and the dll file of the project will be generated in the bin folder of the corresponding project path.Use the netload command in cad to load the relevant dll files, and you can get the relevant results.
- Extra chapter
In addition to the above methods, CAD also provides secondary development methods such as C++ and VB.The figure below shows the ability and learning difficulty of developing CAD in various languages.
In terms of programming learning efficiency and ease of use, various programming languages have their own strengths and weaknesses.Everyone can choose different methods to carry out related secondary development according to their own needs.Judging from the numerous CAD plug-ins in your collection, the utility of mastering a secondary development language of AutoCAD is self-evident.The feeling of pleasure when using plug-ins written by myself is much greater than using Explorer Shenma!
References: Wilson Wu .NET-based CAD secondary development (introduction) Structural Utopia https://mp.weixin.qq.com/s/i2Ql_5-yI0Lv7ZpfByCYOw
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