How to program a chess: a forum based tutorial

llvllatrix · 2005-04-02T02:01:34

Introductions (ie what the heck is this thread about): This thread was born when da_grat1 asked me about model loading. After a bit of discussion it turned out that he was trying to program a chess game and wondered if I had any advice. The result; a good excuse to talk design. Although this may seem off topic on this forum, I think nehe is best for several reasons. This forum has a wide variety of visitors, both advanced and beginner (you'll see why this is important later...keep reading :) ). I also dont have to go over OGL, which we will be using to do our graphics. Most of you have also already taken a look at some general demo design as well as loading and playing sound, which is a bonus. Also note that da_grat1 will be trying to implement this, so I'm going to try my best to keep us on topic and drive us through the end. k, so its obvious that i cant tell you that if you follow steps 1 - X you'll successfully complete your project, or game ect. (lol, its just not possible) Instead, what I want to do with this thread is to start a discussion about game design from start to where ever we take it. Consider this an online, dynamic tutorial with many authors. You guys should feel free to tell me that I'm wrong (giving a reason for your decisions is very important because we are all of different expertise in different areas). Remember that even if you feel you cannot contribute because you dont have the experience, asking questions is just as valuable (they determine where this discussion will go). Questions you guys ask will determine what issues get addressed and in what order. So sit back and get ready for what will hopefully be a long and productive discussion. I think the best place to start is at the beginning. You'd be surprised how many people dont start there. Imagine how terrible it would be if you hired a company to build you a corporate headquarters for your multi-million dollar game development studio and when you open the door, the thing crashes down on you. Then, when your in your hospital bed you find out that its because the guys who built the place didnt do any planning or draw any blue prints and just started building the place without thinking twice. The reason this kind of thing doesn't happen with building companies is because architects and engineers design and test the building long before anyone uses a hammer or saw. However, this happens all to often in software engineering; people just dont start at the beginning. They jump into projects and start coding without design documents. Remember your friend who said he would make an amazing game and ended up not finishing it? Its because when he was nailing some code together, the structure fell straight down on top of his head and he couldnt continue...anyway I tink I made my point...design twice, build once...so lets get to some code design...that and I ran out of building analogies ;) ... Programming is like chewing a pack of bubble gum. If you chew it all at once you're going to die. Its best if you divide the pack into pieces and chew each separately. There’s no guarantee you're not going to choke on a small piece but at least if you do you can probably spit it back up. So the first thing to do is establish exactly what we hope to accomplish and then keep breaking it down till we can implement it. To break it down on a business level, the "what are we going to do" is the project proposal. The "break down" is the design document/feasibility study and the implement it is "code till it works". Side trackin': In this quick paragraph I'm going to describe my tendencies when it comes to game programming. Most of the reasons for this stuff comes from code on the cob (http://www.gamedev.net/reference/list.asp?categoryid=45#115) and we'll hopefully see it used and justified further on in the discussion. Game programming (unlike word processors) are made using synthesis. We are going to take elements like graphics, audio ect and put them together to make a product. To do the synthesis I typically use function libraries as the glue that holds my program together (think OpenGL's interface). Classes and inheritance usually dont work for this kind of thing (think MFC). I'm not saying to totally abandon classes, I'm saying "use them to do a job behind a function library so that whatever uses the library doesn’t have to know about them". Keep your interfaces clean and whatever you build with them will look ok...irregardless of what is behind the interface. What are we going to do? So we're making a chess game. It will have 3d pieces that move accross the board (as apposed to appearing where ever you clicked), an animated camera, ai which you can play against (not good ai, but ai none the less), a console for testing (not as complex as you think, but it will just take a long time to implement), sound for coolness, and the ability to save your game. That sound good to everyone? How are we going to do this? Well, first step is decomposition, but what exactly does that mean? If you refer to my side track up there, why are we decomposing, shouldn’t we be synthesizing? In truth, there are actually two different phases here that use different techniques to get their jobs done. The first phase is the design phase where we decompose our problem into sub problems till we are satisfied we can tackle them. Then we go to the implementation phase where we take the easiest sub problems, solve them, and their solutions to solve larger problems till we have a final solution; our game (this is what i mean by synthesis). So what is this design thingy all about? Decomposition is the answer to the question, "how the hell am i supposed to do that?" Design is about making a decomposition that works both now and in the future (you'll see what i mean). Pop quiz: what did a software blue print look like back when king tut was writing security software for his sarcophagus (namely the 7 Egyptian curses of death)? Ans: Same as they look today ; a pyramid. On the top of the pyramid is our goal (namely, a game) and on the very bottom is stuff we know we have to use to achieve our goal (our requirements). I our case, we have stuff like OpenGL, Windows, and fmod on the bottom. At the top of our pyramid is our chess game. Let the designing begin: A quick way to start is by listing a bunch of stuff you're probably going to need. In any game, we're going to need a main screen (the thing people see when they start the game), a game screen(the game itself), a menu (drawn over the screen), a way to tell if the game is over, a way to tell what screen gets input, a way to get the input, a way to keep track of time, a way to draw objects as apposed to triangles, a way to easily play a sound, a way to load files, a way for the ai to think, a way to control the camera, and a whole bunch of other stuff. The next thing to tackle is to organize this stuff in a pyramid and then fill in the gaps where we need to. We then keep doing this (decomposing these subsystems) till we can implement each subsystem without having to decompose it. So the next thing to tackle is to rearrange the subsystems i've listed (as well as others you guys come up with) into the pyramid and this i'm going to leave to anyone with time on their hands (this is a good exercise to do) or to my next post (which ever comes first). will post later, - llvllatrix

llvllatrix

Author

340

March 13, 2005 08:11 AM

Quote:
The next one is you are going to implement the SDL and UI right...that means we should be able to load the graphics aswell right..?

Yup. Once we finish the SDL and UI wrappers we can start making the game specific components of the engine. By this I mean each of our contexts which compose our main game screens.

Quote:
ick, the basecode for this is a pain, I dunno what state 11v11atrix is at, but I'm gonna start busting out wxWindows on this thing, and see where I get to, his basecode is all totally windows centric :(

lol, I was affraid of that. Perhaps we could move all of our ui specific code onto the console? The systems that should be moved are the display error subsystem and the loading dialog. We should be able to accomplish both using text. This way all of our code should be cross platform except for our timing code and our disk access code. We should be able to use SDL to do both. Is there anything else we should change?

Cheers,
- llvllatrix

da_grat1

122

March 13, 2005 10:00 PM

llvllatrix.. I believe you almost done with the SDL wrapping right.. :)
I think the only left is to load the graphic, moving the pieces and menu..
Do we need to use the same method to load the graphics? and how about moving the pieces... array is required right...?

[Edited by - da_grat1 on March 13, 2005 10:00:34 PM]

da_grat1

122

March 14, 2005 01:11 PM

after I go throught the lastest code.. I figure out that most of the codes have been modified..

I don't think I can use you the same method to load the graphics.. :) ...
yo llvalltrix.... any progress...

llvllatrix

Author

340

March 14, 2005 01:22 PM

Yup; I have an sdl window up. We should be able to get rid of the gl basecode soon and start working on our own.

da_grat1

122

March 14, 2005 02:16 PM

that means, you are going to upload the latest source code soon... then the next tutorial will be the graphics... :)

da_grat1

122

March 15, 2005 04:18 AM

llvllatrix... Will it take to long to load the graphics? Are we going to use mouse pick drag the pieces.. maybe I've been asking this many times.. :P ..I just want to know the details... I think mouse dragging is the most difficult part... I wonder when are we going to start doing it..I am very curious...
How is your SDL window...? :)

llvllatrix

Author

340

March 15, 2005 11:32 AM

Quote:
llvllatrix... Will it take to long to load the graphics? Are we going to use mouse pick drag the pieces.. maybe I've been asking this many times.. :P ..I just want to know the details... I think mouse dragging is the most difficult part... I wonder when are we going to start doing it..I am very curious...
How is your SDL window...? :)

Hey,

I've been thinking about the input mechanism. There are a few things we could do. Unfortunately, my development pc is almost dead. I've had parts ordered for it and they should be here within the week. In the mean time I can use another machine to basically work out the final design of the game in documentation.

In professional game development companies the ui teams usually write a bunch of docs on standards ect while the programmers are busy laying out the bottom layers of the game. Standards describe how the ui will look, how it will behave if you click cancel and other details. Since we're acting as the entire dev team we also have to go through this process if we want our game to have a consistent feel.

Some of the things i'll be discussing are things like what options are first cut will support (none actually). What ui components will be supported in the main hud. The options that are avaliable through the submenu. I'm thinking of foregoing the console for the time being. Is that ok with everyone?

Cheers,
- llvllatrix

da_grat1

122

March 15, 2005 02:35 PM

Quote: I'm thinking of foregoing the console for the time being. Is that ok with everyone?

But we have been in the console for most of the time.. at least we do something else like dragging the pieces.. that is what I really want to learn :)

llvllatrix

Author

340

March 15, 2005 02:44 PM

Quote:
But we have been in the console for most of the time.. at least we do something else like dragging the pieces.. that is what I really want to learn :)

lol, sry i should have been more clear. By console I mean a console like the one in Counter Strike. Its basically like a command prompt in the game that will let you call functions in the game for testing. I personally dont think its important for a game this size.

We'll be sticking to a basic 3d chess game where u can click and drag to move pieces.

Ceers,
- llvllatrix

da_grat1

122

March 15, 2005 04:24 PM

Quote: By console I mean a console like the one in Counter Strike

wow, that's great, I remember last time I used to play counter strike with my friends in college.. we used to go to the cyber cafe when we are having stress and go kill people..I mean play counter strike... lol.. :)

Quote: We'll be sticking to a basic 3d chess game where u can click and drag to move pieces.

Really, :) thanks... I have been waiting for that for a long time... Now I finally have the chance to learn that.. so where should we start.. do we need to put all the pieces into array..
I too excited right now.. :)

How to program a chess: a forum based tutorial

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