Hands-on Introduction to VB.NET Add-Ins for AutoCAD

JERRY WINTERS: This session is being recorded. Please don't hesitate to ask questions if you have questions. Even though it's being recorded, I'll try to repeat the question to make sure everyone hears it. And we can get that on the recording as well. So just fair warning, anything you say can and will be used against you. All right?

There are seats available. If you want to drive and you're not driving right now, if you don't have an actual keyboard in front of you, you're welcome to come up here and use the presentation computer and I'll just kind of stand behind you and let you do it. If anyone would like to do that, that would be just fine. OK. All right, so we've got a couple here. So if you want to drive, there's a couple of people here that have laptops that they could actually do stuff on. So let one of the assistants know if you'd like to drive, and they can kind of curate that.

All right, I think it's time we get started here. Welcome to the hands on Introduction to VB.NET add-ins for AutoCAD SD 197926-L class. My name is Jerry Winters. I'm excited to be here. Glad to be here with you. My goal today is to have you leave and have you be able to go back to your homes, back to your offices, and create a brand new project from scratch. Get some code in there and make it work. That's my hope and my goal with this class.

And so we've got excellent assistants here to help you with that as well. We've got Carl, James, and [? Yuri ?] that will be assisting you with that. So if you have questions or problems, feel free to raise your hand. If you're watching this class online after the fact, let me give you the cell phone numbers of these guys and you can just call them directly, right? Maybe not. All right.

We're going to have four primary learning objectives today. First of all is how to create a new AutoCAD add-in with VB.NET. Next how to create a new command in VB.NET. And next, learning the basics of drawing in AutoCAD through the .NET API. And last, how to extract block and attribute information to the .NET API. In the handout, there's a little section called extra content. If we have time to do some more stuff, we will. And once again, please feel free to raise your hand or ask questions if you have any questions. Let's jump into it.

The first thing you need to know is that we'll be using the Visual Studio 2017 Community Edition. This is a free thing from Microsoft. You can go to their website. It's in the handout as how to get it. You can download it, install it. And everything we do in this class is based on that free version of Visual Studio. You don't have to go out and buy Visual Studio Professional or anything like that. It won't give you anything extra that you need that we're doing in the class today. So that's the first things first. In the lab here, though, those are already installed here.

All right, let's jump into it. How do we create a brand new AutoCAD add-in in VB.NET? First of all, we're using Visual Studio 2017 and AutoCAD 2019 is installed here. So Visual Studio should already be started for you on the left hand side of your screen. If you'll go to the Menu, go to File, and down to New, and then over to Project. File, New, Project. On the left hand side, you'll notice there are several different types of templates going on here. You want to pick Visual Basic. Pick Windows Desktop. We want class library .NET framework. Yes?

AUDIENCE: [INAUDIBLE]

JERRY WINTERS: Great question. The question was, how many versions back will this work? In other words, maybe you're not on-- you'll be just fine. You'll be just fine. So if you're in 2016, you can run through this as well. We'll just pick different DLLs than you'll pick on your laptop.

All right, so we're going to pick class library. Let's give this a project name called Program A. Now, you want to take note of the location. Mine says C users mainframe two source repos. That's what mine says. We want to keep note of that in our minds where that's at. There's little checkbox here that says Create Directory For Solution. We want that off. Just turn that checkbox off.

And lastly, we want to make sure that the .NET framework here is 4.7 or above. So we're at 4.7.2 on this particular machine. Now, this is for AutoCAD 2019. Prior versions of AutoCAD, you'd want to select probably a prior version of the .NET framework. So for 2016, you're gonna go to 4.5, 4.6 for that.

So let's see here. I've got Windows Desktop .NET framework class library. My name is Program A. I'm looking at the location. Got that. Framework 4.7. I've turned off my directory for solution. I'm going to click the OK button now on the keyboard. And I have a brand new blank project.

I'm gonna stop right there. Let's make sure that everyone is up to speed here. Does anyone need help getting to this point? Excellent.

All right, so first step is to create a new class library. Second, we're going to add some references. So go to the menu. Actually, that has to be third. We started Visual Studio. Third, we're gonna add the references here. So go up to Project and down to Add Reference. In the menu in Visual Studio, Project, Add Reference. We're going to go to browse on the left hand side here. And then we're gonna click on the Browse button at the bottom.

So what we're doing here is we're telling our project there are three DLLs that I want to be able to communicate with and understand. Three different DLLs. So we're going to browse for those. And I'm just going to go to C, Program Files, Autodesk, AutoCAD 2019.

Once I get to this point, you'll notice in really big letters in the handout, we're going to type in AC star MGD dot DLL and then hit Enter. AC star MGD dot DLL Enter. And then we're going to scroll down. The AutoCAD 2019 directory, as well as the 2018, 2017, et cetera, has a lot of files in there.

If we type in AC star MGD dot DLL and hit Enter, it will filter and only show us the files that meet that criteria. Makes it a lot easier to find those three DLLs that we're looking for. And they just happen to be the ones on the top here. AC core managed, ACDB managed, and AC managed dot DLL. Those are the three DLLs we want. Three DLLs. AC core, ACDB, and AC managed. All right.

Next thing we'll do is click on the Add button. And then we'll click on the OK button. And that's where we're at. Does anyone need help getting to this point? This is actually the most challenging part of the whole class, I promise you, is creating a new project. There are a number of steps. If we get them all, we're in great shape. If we miss one of them, then things aren't going to work right. So all right, let's move on.

We have our three DLLs referenced. The next thing we're going to do is we're going to set a property in the debug window. So File. Sorry, not File. Project. Down at the very bottom here, mind says Program A properties. If your program is named Program B, then it'll say Program B properties, Program C, whatever. So we'll click on Program A properties.

And then we'll click on the debug node over here. And we're gonna click on the Start External Program radio button here. What we're doing here is we're saying, when I start debugging my program, I want you to start AutoCAD. So Project, down to Properties, Debug, Start External Program. I'm just going to type it in, but you can browse for it if you wanted to.

We want the path to the acad.exe file. That's what we're looking for. The path to acad.exe. What we're saying is when you start the program, that's where we want to start. OK, we'll stop right there for one second. Is everyone good? Raise your hand if you're not to this point here.

All right. So if we'll just go ahead and go to the next page. We're now on page nine of the handout. So the fifth step in writing a VB.NET add-in here is to write amazing code. Now, we're not going to do that yet. What we are going to do is we're going to click on the Start button. At the very top of the screen here in Visual Studio, you see a button that says Start. So go ahead and click on that. And if things are all lined up correctly, what should happen is AutoCAD should start.

So what happens is when Visual Studio starts AutoCAD, there's a link between Visual Studio and AutoCAD. They're actually communicating with one another. And depending on which windows are showing in Visual Studio, you might see a bunch of debug messages from AutoCAD as well. So you can see here the AutoCAD is starting up.

Now, notice that it actually takes a little time for AutoCAD to start up. Takes a little time to get it going here. So we really don't want to have to do that every single time we're actually trying to change our code and work through our code. And we'll get to how we take care of that.

All right, next thing. Let's click on Start Drawing. We'll just start a blank AutoCAD drawing here. All right. Bring this back up here. So when we click the Start button in Visual Studio, here's what happens. The first thing is Visual Studio saves our project by default. So any changes we've made to our code, they get saved when we hit the start button. Visual Studio compiles our code into a DLL. And we added three DLLs as references, and so it brings those DLLs over as well into the project directory.

And it also brings any of the supporting DLLs that they may need. Then Visual Studio starts this external program. We told it to start AutoCAD for us. And that link is created. Once we're here now, what we want to use is the net load command. So we're on page 10 of the handout. So inside of AutoCAD here, I'll type net load. N-E-T L-O-A-D. And hit Enter.

Now, when we first started our project here, one of the directories was, what's the project directory? Where are we going to store this? And so that's what we need to browse to now. So I'm going to go to drop this down here and we're gonna pick on mainframe two. That's the name of the computer I've got here, or the user. Your user will be a little bit different probably. There's an easier way.

AUDIENCE: [INAUDIBLE] Go to File. Start screen. And it'll bring you up to your project. You can right click on your project [INAUDIBLE].

JERRY WINTERS: OK. So you're saying--

AUDIENCE: Go to File.

JERRY WINTERS: File.

AUDIENCE: Go to start page.

JERRY WINTERS: Start page.

AUDIENCE: Right click on your [INAUDIBLE].

JERRY WINTERS: OK. That works too. Good idea. Thank you for that. If you get lost on that, other options are you can also go to your Solution Explorer and look for a file there and look at the properties of that file and see what the path is of that, that kind of thing as well. There's the same path there. So several ways to get that.

So my user. There's a directory here called Source and then a directory called Repos and there's my Program A and Bin and Debug. Now, it's a lot of, so I'm just gonna open this window here leave it there. And if you have a hard time finding your project path, just raise your hand here if you need a hand getting to this. Yeah, debug bin. Right. Or bin debug, sorry. Bin debug. That's the path you want to be in.

And you look in there, you'll see a bunch of AC windows dot DLL, Autodesk AutoCAD interop common DLL. Bunch of DLLs in there. And what we want to look for is the DLL of our project. So if I pull this down just a little bit here, you'll see we've got this Program A at the very bottom down here. So pick your DLL, the DLL you just created, by starting the debug process. Once you get that, go ahead and click the Open button on that dialog.

Now I mention this is the most challenging part of the whole class, getting this project started. Once we get to this point and we get to where we can do this comfortably, getting the code in there is pretty easy to do. Anyone have any problems? Raise your hand if you have any issues.

So when you click on Open, you might get a dialog that says, do you want to load this application always, just once, et cetera. I haven't shown that on my screen yet here. You can click Always or Just Once. It won't really matter, because the next time you compile it, it will ask you that again. If you're tired of seeing that, you can set your secure load variable to 0 and that should disappear. Thank you.

OK, if you successfully were able to load your application. Let me finish the process here on the screen. So in my screen here, AutoCAD has loaded that application now.

Now, the question is, what can I do with my application? Nothing, right? We didn't add any code to it. What we did is we successfully created a new VB.NET add-in that does nothing. We're going to obviously do some things in a minute.

What I'd like you to do-- and this is going to seem kind of chaotic. It's OK. If you have a question, just raise your hand. I'd like you to close down AutoCAD and close down Visual Studio and go through that same process two or three more times. You should be able to get to the point and you can actually create a new add-in in like a minute. All right?

So take a second. I want you to go through the steps again several times. Get used to it. Get it to where you can feel comfortable doing that. So it's going to be a little noisy and a little chaotic, but go ahead and do that just two or three times. Create a new project. Call it Program B, Program C, Program D.

So a question was asked, is this the process we go through every time I create a new project, a new program or whatever, some kind of a template that I use? So in the Community Edition, this is what I do. There is a way to save a template, but it doesn't always get everything that you need settings wise in the template. So this is what I do. It takes less than a minute to get it set up. And then kind of go from there. Now, there are other ways we can get our code easy to access and drag and drop things into a project, and we'll kind of go through those too. Great question, thank you.

So I'll go through on my screen a few times the same process. I'll close down AutoCAD. Visual Studio closed down. The server will stop itself in just a second now that AutoCAD is closed. There we go. File, New Project. Window Desktop. Class library. I'm gonna call this project or Program B. That's where I'm saving this. .NET framework's good. I'm not creating a directory. I'll click OK. All right. That's good. Let's go back to the handout here. Make sure we follow our steps correctly.

All right, let's add our references here. Project. Add Reference. Now, you'll notice that now that we've added these DLLs before, they actually show up in our recent list. So we don't have to browse for it every time. I've got my three references there. That's good. Let's set AutoCAD as the start up project. Project Properties. Debug. Start External Program. Program Files. Autodesk. Be right with you.

AutoCAD 2019. acad.exe. That's what I want right there. All right. I hit the Start button on the Visual Studio. AutoCAD starts up. Let's start a new drawing. Net load. Catch us up here on that. And we're not in the Program A anymore. We want to skip over to Program B. Bin. Debug. And there's my DLL. Open. Always Load. And we're good to go.

OK, a question was asked about the DLLs. A couple of questions. So each version of AutoCAD has those same three DLLs, at least the last number of years, has those same three DLLs located in their paths. So if you're programming for AutoCAD 2017, then you'd browse to the AutoCAD 2017 directory and pick those same three DLLs.

Now, a question was asked about would it make sense to copy those to some other directory? If you go to Google and type in object ARX SDK, object ARX SDK, you can download the Software Development Kit, that's SDK, from Autodesk for current versions of AutoCAD as well as prior versions of AutoCAD. And in those downloads are the DLLs that you need. So even if you don't have AutoCAD 2017 on your computer, you can download the ARX, the object ARX SDK for 2017. You can pick the three DLLs out of that download and compile it.

So even without AutoCAD 2017 on your computer, you can compile against those DLLs and then distribute your DLL to people that have AutoCAD 2017. So that's preferable to actually copying and making your own little directories, because they have all the other supportive DLLs that they need. So that's the object ARX SDK.

How are we doing? Are we creating projects? Everyone good? You've created a couple, two or three maybe? All right, now seriously, that was the most challenging part of the whole thing. There are specific steps that have to be followed. If you follow the steps, you're going to be in great shape. We good?

All right, who's ready to write some code? Go ahead and shut down AutoCAD. Let's get back to Visual Studio. And let's create a new command in AutoCAD.

All right, our second learning objective here is how to create an AutoCAD command. Now, when you and I use the line command in AutoCAD or the circle command in AutoCAD-- I'm old school. I'm typing it at the command line. I don't know what you're doing. You might be hunting for the button. But I'm just typing it in. You might have little shortcuts to commands in that.

But the first thing you need to ask yourself is, what do I want to name this command? My guess is it would be a bad idea to create a new command called Line. We don't want to try to step on the toes of something that's already in AutoCAD. So we see here that we're gonna create a new command called Run Me. Now, I don't know if you've heard of Hello World. Who's heard of Hello World? Most of you that have done software kind of things. This is my version of Hello World. If you want to type Hello World instead of Run Me, that's fine. I'm just anti Hello World. So we're creating a new command.

What we're going to do is go to our project and go into the class of our project and type in the code we see here in the window. So Autodesk dot AutoCAD dot runtime. Now, if you watch my screen for one second, I typed in RU for runtime. And you'll notice runtime is selected. If I hit the Tab key on the keyboard, it fills it in for me. So once in a while, it might seem like I'm typing really fast. I'm actually just using the Tab key.

So we're creating a new command called Run Me. Very simple command. A message box that says I hope this works. I'm going to make my text a little bit larger here. That might be easier to read. That's a little better.

So when you use net load in AutoCAD, one of the things that happens behind the scenes is AutoCAD looks at your DLL and looks for any command methods that you may have created, because it needs to add those commands to its little stack of commands that you can run. So we're saying I've got a new command I'm creating called Run Me.

Go ahead and type it in. As you're typing, kind of keep your eye on the screen. See what's happening. Visual Studio is always trying to give you more information and give you feedback and give you helpful hints. So kind of keep your eye on the screen a little bit and see what's happening. See how Visual Studio is helping you.

OK, once you get your command written, go ahead and run the start button again. That will start the debugging process. It will start AutoCAD. You'll type net load. You'll pick your DLL, and then you can run the Run Me command. All right? After you successfully run the Run Me command, don't close down AutoCAD. Just leave it there for a minute, all right?

All right, does it work? Does anyone get a message box? I hope it works. I hope this works. Let me try running mine here. I'll click on the Start button. That will start AutoCAD for us here. It works. Good.

Now, I've got to tell you, as a instructor here at Autodesk University, now we've gotten through this, and I'm very impressed. In a half an hour, we've created a new program for AutoCAD and a new command in AutoCAD and it works and that's awesome. Most instructors at Autodesk University, if something doesn't work, there are a million things they can blame it on, right? It's got a bug in the software. The hardware has got problems.

Well, if it's a bug in the software, whose fault is it? It's ours now, right? So that's kind of the scary thing about this type of a class. But if we've gotten to this point, we're going to do awesome. We're going to be in great shape. We're half an hour in. We're already creating add-ins for AutoCAD. Yes, question over here?

All right. So we're going to talk about what just happened here kind of line by line in the handout, all right? I'll click on OK here. Let's talk about what's happening here. I'm gonna widen this up so we can see it's nice and big.

All right, first bit of code here. Autodesk, AutoCAD, AutoCAD. Sorry, Autodesk and AutoCAD runtime command method, Run Me. That line of code says, I want to create a new command that can be run inside of AutoCAD called Run Me. All right, that's all that's happening there.

It's always placed directly above a public sub statement. Public sub means I've got a procedure that I want to create now, and I want it to be able to be called from outside of the class that it's in right now. That may mean nothing to you at all right now, and that's OK if it doesn't. But that's what's happening. And then it also has a name, and I've named this Run Me. Now, does the AutoCAD command have to be named the exact same thing as the procedure command? It does not. But I don't know why you'd want to have them named differently. It's just easier to find things.

Next thing we have a message box. Message box. We're applying a parameter that says I hope this works. And then we have end sub. So everything between the sub and the end sup is what gets run when we run our command called Run Me. All right, very simple, very straightforward.

There's our command Run Me. We've gotten to that point. Here's we're right now. We're on page 14 of the handout if you're following along. What I'd like you to do is we're going to add a break point now. So hopefully AutoCAD is still running. Don't close down AutoCAD if you did, go ahead and start the debugging process again by clicking Start. We're going to go back to our code.

And in the gray column in our code, we're going to click right here. I'm going to kind of click it on and off here. We're going to add a break point. The break point says, as I'm debugging this, when you get to this line of code, stop. Don't actually execute this line of code. Just stop there for a minute. That's called a break point. And we're at the bottom of page 15 in the handout here. 14. I'm sorry, bottom of page 14. Sorry. Bottom of page 14.

Now, with that break point in place, go back into AutoCAD now and run your command again. Run Me. Hit Enter. What should happen-- remember when we start the debugging process, a link between AutoCAD and Visual Studio gets created. I type the Run Me command in AutoCAD and it sees a break point in Visual Studio. It jumps back to Visual Studio.

Now, you'll notice the whole line there is now highlighted in yellow. The yellow line means this is the line of code that is next in line to be executed. So it already ran the public sub line. Now we're going to do the message box. What I'd like you to do is look on the keyboard for the F11 key. F11.

If I hit the F11 key, what should happen is we should jump back into AutoCAD, because that one line of code, I basically said run one more line of code, F11. Jumps back to AutoCAD. Shows the message box. If I click on the OK button now in AutoCAD, it jumps back over to Visual Studio.

Now, you've seen that it takes a few minutes. Well, not a few minutes. I take that back. It takes a minute or so for AutoCAD to start every time we start debugging process, right? If you had to start AutoCAD, try it, close AutoCAD, make a change, start AutoCAD, try it. If you had to do that every time you made a change to your code, it would take forever to write code.

What I'd like you to do is change. Now, I'm back in Visual Studio here. Change from I hope this works to I'm glad this works. So change the text from I hope this works to I'm glad this works. So remember, AutoCAD is still running over here. Visual Studio is running over here. And we just changed our code without stopping AutoCAD, without stopping Visual Studio and recompiling. We just changed our code.

Now, big warning here. If you're working with prior versions of AutoCAD, this does not always work. There were issues with the edit and continue with some prior versions of AutoCAD in 64-bit environments. If you're running a 32-bit environment, it works fine. So just a big warning. If you're working in prior versions of AutoCAD, it might make sense, if you can't get this to work in prior versions of AutoCAD, it might make sense to run it as a 32-bit AutoCAD 32-bit Visual Studio and a 32-bit version of Windows. All right?

When this kind of came out and it didn't work for me, for my projects, it made sense to actually have a VM running, just a VMware machine running a 32-bit Windows with 32-bit AutoCAD, 32-bit Visual Studio in there. So I could write all my code in there, and it was writing code that was shared back to my 64-bit operating system. So just be aware that. If you go back and it doesn't work, that's why.

All right. What I want to do-- I just made a change to my message box, right? I want to sear this run again. Now, I could let the code finish and then just type Run Me again. But I don't want to do that. What I want to do is grab this arrow over here. Grab it, drag it, and drop it back up on line four.

Drag and drop the arrow back up on line four. What should happen is that line should now be highlighted in yellow. And now if I hit the F11 key again on the keyboard, I now get I'm glad this works in my message box. I say OK that. I'm back to my end sub now. Remember, end sub hasn't run yet. I'm still in my program. I'm still in my command called Run Me. I could change that message box again. I could write 2,000 more lines of code and then go back, drag and drop the yellow arrow.

Now, right now we have, what, one line of code, right? A message box. And dragging and dropping the little yellow arrow thing is not too bad right now. If you had a lot of code, though, it would become a little more difficult. Here's what I prefer to do with this. I prefer to come up on the line that I want, just kind of click on there, then do a right click and go to Set Next Statement. That's what I prefer to do, because that way I know I'm going to get it.

Sometimes when you're dragging and it's scrolling and stuff like that, things don't work terribly smoothly. I'd rather scroll to the line I want, right click, Set Next Statement. Set Next Statement. That's at the bottom of page 17. F11 on the keyboard. There's my message box again. Right click, Set Next Statement. F11 on the keyboard and OK.

All right, how are we doing? Is everyone up to speed here? Excellent. All right. Let's do a little more code then, shall we? Right now I'm in the debugging process. You'll notice up here it says debugging on Visual Studio. We're on the end sub. I've got some options. I can hit F11, and that'll go to the next line. Or I could hit F5 on the keyboard. F5 means just run it. So I'm just going to hit F5 on the keyboard and let it finish running that amazing command.

All right, let's go to page 18 in the handout. OK, showing a message box. Not the most amazing feat, I know. So let's talk about drawing inside of AutoCAD.

There was a time when our AutoCAD DWG files would get corrupted a lot. I don't know if any of you are old enough to remember when that kind of thing happened, but that seemed to happen quite often. Especially with AutoCAD version 13. Remember that? Interesting version of AutoCAD.

So in order to keep our drawing files from getting corrupted, what we do in our code is we do everything under the umbrella of a transaction. So a transaction is basically saying I'm going to start doing things to the database, and if there's something wrong inside of our transaction, then the thing that's wrong happens inside the transaction and doesn't affect the rest of our drawing. That's one way to describe a transaction. It's basically a way to make sure our drawing files don't get corrupted. Everything happens under this umbrella of a transaction. That's one thing you need to kind of understand. And we'll see this in a second.

We're going to take a look at some code here. Before we do that, let's do this. I want you to copy the code from the PDF file, the handout. Copy that. I need to close down AutoCAD here. Go ahead and close down AutoCAD. Let's get back to our project in Visual Studio. So copy the imports code. And this goes at the very top of the class, above the class.

AUDIENCE: Close AutoCAD?

JERRY WINTERS: Close AutoCAD, yeah. Go back to Visual Studio. And we're going to copy and paste the import statements. Now, our Run Me command is Autodesk dot AutoCAD dot runtime. That's called a namespace. If you have to type out all that stuff every time you use something in that namespace, your code is going to look really crazy. So what we're going to do to simplify things, we're going to import some namespaces so we don't have to type that over and over and over again. So copy and paste the import statements.

Next we're going to take a look at this code here. Here's my command method here. It says draw a line. What am I going to do? I think I'm going to draw a line. In our code, we get the current document. And then we get the database of that document. An AutoCAD DWG file is a database. It's a database like any other database you've seen or used or worked with or heard about. An AutoCAD DWG file is a database.

The AutoCAD program, the editor, is a graphical interface to the database. So databases have tables. Database tables have records inside those tables. So in AutoCAD, we have-- this is how we talk to our files. So we get the database of the active document, and then we get the editor of that document as well. The editor is the window that you and I work in when we're working with AutoCAD. If I want to draw a line at AutoCAD, I type line and I pick my two points, then I've got a line. So we're getting the editor, because we want to have some interaction with that.

And then we start this transaction thing. We start a transaction. And then we get the current space. Am I in model space? Am I in a paper space layout? Where am I? We get the current space, whatever that is. Now, in AutoCAD programming, we go to the object ID, and we get that object for either read or write.

In this case, we're just going to open that up for write. We want to add something to that line. So we're gonna open it for right. If some of this is totally going over your head, please don't get concerned. That's OK. So we're going to get a variable here named my BTR. It's a block table record. And we're getting the current space. This will be model space. That's what we'll do today.

The next thing we do is have a variable here. So [INAUDIBLE] means we've got a variable. Its name is start point. What kind of an object is it? It's a point 3D object. And I'm going to the editor. That variable is set up here. I'm going to the editor and saying, I want to get a point. And here's what we want to prompt the user to say. Select start point. I want to get the value of that get point.

The next thing we're going to get a prompt point option, because we want to have the same rubber band type effect when we pick our second point. Now, once again, if this is kind of you feel like it's going over your head, don't worry about it. Just kind of be patient with yourselves. So we want to create the rubber band effect when we pick the second point. We do that through something called a prompt point option, which is here.

And then we use that my PPO variable over here when we get that second point. So we get point again. Only instead of saying what the prompt is here, like we did up here, we use a prompt point option. We'll step through this code so you can see how it works. Then we create a new line based on the selected start point and end point. We append it to model space or paper space. We add it to the transaction, and then we commit the transaction.

Let's copy and paste this command from the handout into our project. Now, pay very careful attention. You don't want to copy it inside the sub that's already there. I'm just going to enter, make a big space here. It needs to be inside the class. So I'll copy and paste my code, and there it is. Once you get to this point, go ahead and start it. Start the debugging process. Try running your draw line command and then don't close down AutoCAD. Do not close down AutoCAD, please.

So the question was-- well, actually, I'll answer that question in a minute when we get back to the code. Let's go ahead and run the code. And if it works, we're in good shape. Is anyone drawing lines yet in AutoCAD? OK, who's drawing lines in AutoCAD? If you run it, it should ask you to pick two points. You should see the rubber band effect from the two points there.

AUDIENCE: [INAUDIBLE]

JERRY WINTERS: No, this is called draw line. So let's net load this. And there's Program B. That's fine. Draw a line. There's my start point. There's my end point. OK, if I come back to model space, I'll run that command again. Start point, end point. [INAUDIBLE] start point, end point. Go ahead and come back into AutoCAD here. Or in Visual Studio, I'm sorry. And add a break point somewhere. Then go back AutoCAD and start the command again.

AUDIENCE: Anywhere?

JERRY WINTERS: Anywhere's fine, yeah. Anywhere's fine. Let's take a look at that. So I've got my break point here.

Now, someone asked a question about how do I find help about this certain thing? How do I find out about how this thing works for any object? So let's just talk about a couple of things that Visual Studio does for us here to help us out.

First of all, when you're in the debugging process, Visual Studio will tell you about stuff. If I hold my cursor over my editor and drop that down, it will tell me the properties of that editor. If I go to my DB and drop that down, we're gonna see a lot of properties. Ready? I'm scrolling through it here.

I can see my A units is set to 0 and my add mode is set to one. I can see my current colors by layer here, my line weight, my chamfer A, B, C, D. I can see-- what else can I see here? Dim vars. Who loves dim vars? There they all are, all my dim vars for this database. So lots of dimensioning variables there that I can look at.

So as I go through the debugging process, what hopefully is happening is I'm kind of seeing little things here. I'm learning about things. If I want to find out what the current dim scale is, I can come here to my database, and let's see if we got dim scale here. Is dim scale here? Is dim scale here? There's dim scale right there. My dim scale is set to one.

So let's do this. Let's step through this. Go here. Next line. My block table record. This is the current space. What is that? Let's go to my BTR. Let's see where we're at here. Does it have a name? Let's scroll down here and see if-- there's a name. The name is star model space. Path name. This is not an xref. Interesting things there in the block table record.

Let's go to the start point. I'll pick a point. Then it jumps back into Visual Studio. Let's come through here. Pick my end point. I'll go boom, pick that point there. I created my new line. Let's take a look at the line object. What's in here? The angle is 0.302. That's in radians. So I can see properties there.

Let's see what else I've got here. The deltas for the X, Y, and Z deltas. That's pretty interesting there. I've got a-- I think I might have a length down here somewhere. There's my length right there. Line type. Line weight. So as you're debugging through your code, take time to look and see what kind of properties you have available to you on those different objects. OK. Yes?

AUDIENCE: [INAUDIBLE]

JERRY WINTERS: Yeah, so if you always want your start point to be a certain coordinate, you can hard code that in. Watch, you'll see an example of that in one second. Yes?

All right. Let's keep going. Let's get some more code in here, shall we? Go ahead and stop AutoCAD. Stop Visual Studio. Stop, stop, stop it. And let's get some more code in place here. So that's just some kind of hints as to get things going here on your debugging your application. Let's come down here and go to the next bit of code here called draw grid.

Now, someone asked a question about if I already know what points I want, what do I do? And this draw grid actually has that kind of an example here where we're actually got points we're specifying. We've got a loop here from 0 to 10 on the x and a loop from 0 to 10 on the y, and we're stepping in half unit increments. Half unit increments.

And then we're seeing-- I'm gonna use the x here for the start point and the x here for the end point and 0 for the y and 10 for the y on this line. And then we come down here and we say we're gonna use 0 for the x, 10 for the x, and then the y variables. So if we run this command here, what we'll get is a grid here. So let me try running this one. So this particular example uses a couple of loops. It uses a loop inside of a loop.

Start a new drawing. Net load. There's my program. I'm gonna go back to model space here. You can do it in paper space. I'm gonna go to model space. And as a matter of fact, let's see here. Are we drawing specifically in model space? No, current space. OK. So we're gonna type in draw grid. Hit Enter, and there's my grid. I'll do an erase all.

And let's come back into the grid here and put a break point there. And then run the command again. Draw a grid. Let's try taking the step on the x at a 0.25 and see what happens. I could step through line by line with the F11 key, but that'll take a while. So I'll just hit the F5 key on the keyboard. And now on the x, we're stepping at 0.25 and the y, we're stepping at one still. Or sorry, 0.5 in the y. What was that?

AUDIENCE: [INAUDIBLE]

JERRY WINTERS: Yeah. So add a break point somewhere in the code. And then make a change somewhere. You can change the step. You can go from 0 to 100 instead of from 0 to 10. Add a break point. Make a change. Hit the F5 key on the keyboard. Remember, you need to start the command in AutoCAD first. So we'll try draw a grid. Hit Enter. I'm gonna change that back to 0.5. And let's try 100 on the x. Run it. And there's 100 on the x.

AUDIENCE: [INAUDIBLE]

JERRY WINTERS: Did you start the command?

AUDIENCE: [INAUDIBLE]

JERRY WINTERS: Yes. Yeah, start the command first, and then hit the break point, and then you can change the code when you're hitting the break point. So you might want to be able to create a program that does some drawing inside of AutoCAD. That might be your thing. If that's the case, you could write code many, many times to draw a line in AutoCAD. You could do that. Or you could create a function that does it for you, that draws the line for you.

So what I'd like to do is close down AutoCAD here. In the handout, let's go over to page now 20. And notice we've got two things here. We've got a draw line function and a draw line test. I'm going to copy both those and paste it into my project here. And let's just take a look at what this draw line function is doing.