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

January 11, 2005 04:33 PM

Quote:
Do u think this tutorial can be finished within this month...?

I think our core engine (the part of the code we can reuse) will probably be finished within a month. Once that is done, we concentrate on the chess specific part (which shouldnt take more than 2 weeks). After that, its touch up and debugging (this part is really fun :) ).

Quote:
What kind of audio files are you going to use?
Loading WAV files using OpenAL is pretty simple, but loading OGGs can greatly decrease the size of the final application (could be useful since it's going to be downloadable; or isn't it?)

You're definitely right, WAV files are out because they would chew up too much bandwidth. I was either thinking OGGs or MP3s. Actually, I was thinking of doing an mp3 player for our unit test :) Do you guys have any preference for either OGGs or MP3s? Does anyone know of any free sound editing software we can use to make our assets?

On a side note, I dont expect sound to be a big part of this game. The only reason I'm including it is simply to show how its done. In fact our final cut (final build) may not have any sounds at all. Once you guys have the sound loading library however, you can easily add this feature and in doing so learn a lot about design.

Will post later,
- llvllatrix

wcm4Him

122

January 11, 2005 05:36 PM

Quote: Original post by llvllatrix
... I was either thinking OGGs or MP3s. Actually, I was thinking of doing an mp3 player for our unit test :) Do you guys have any preference for either OGGs or MP3s? ...
- llvllatrix

Actually I have never used either one of those formats nor do I know how to load them, does any one know of any free online tuts that show you how to load them?????

llvllatrix

Author

340

January 11, 2005 06:11 PM

No worries, I'll give a short tut on how to load the files. Its very easy with the alut library :)

Will post later,
- llvllatrix

llvllatrix

Author

340

January 13, 2005 12:06 AM

Hey Guys,

sry for the lack of posts. I've spent the last few days setting up a new contract, which means that I have to finish this project. Dont worry I'm not stopping :) Starting now you have my full, 8 hour a week, for as long as it takes, attention :D Tomorrow's tutorial will be on OpenAL, hopefully followed by a texture loading tutorial in the afternoon. After that we tackle model loading (we actually load our assets), lighting, and menu creation, which will be the end of our resource manager. Not sure how long it will take, but stay tuned. You guys should have a lot to look forward to on the weekend.

Will post tomorrow,
- llvllatrix

wcm4Him

122

January 13, 2005 12:42 AM

Quote: Original post by llvllatrix
... hopefully followed by a texture loading tutorial in the afternoon.
...

What type of textures will we be using? BMP, TGA, etc.??? I'm familiar with the TGA and BMP format.

Quote: Original post by llvllatrix
... After that we tackle model loading (we actually load our assets), lighting, and menu creation, ...

Also what model file format are we gonna use??? And as far as Lighting and menu creation, I know just a little bit about them.

[Edited by - wcm4Him on January 13, 2005 4:42:16 PM]

llvllatrix

Author

340

January 13, 2005 01:02 AM

Quote:
What type of texturs will we be using? BMP, TGA, etc.??? I'm familiar with the TGA and BMP format.

We are acutually going to use ipicture to load our textures, which can handle bmp, gif, and jpg. We will be using jpg because we want the compression for the net, but the textures can easily be replaced by bitmaps. No worries; you actually dont have to know much about file formats because ipicture handles it all.

Quote:
Also what model file format are we gonna use??? And as far as Lighting goes , I know just a little bit about it (enough to get me by).

In both cases, we are going to specify our own format and load it into our engine. We are actually going to write plugins for Milkshape3D to export to our specification but if you wanted to, you could write an export plugin or file converter for whatever editor you want to use. I choose milkshape because it is easy to learn, easy to write plugins for, has a 30 day free trial, and costs $25.00. A plugin is essentially a dll that milkshape uses to extend its functionality. No worries if you dont know about dlls; dlls are really easy to learn and I'll walk you through the entire process :)

Will post later,
- llvllatrix

wcm4Him

122

January 13, 2005 04:02 PM

Quote: Original post by llvllatrix
... No worries if you dont know about dlls; dlls are really easy to learn and I'll walk you through the entire process :) ...

That'll be good cuz I know nothing about a DLL other than what it stands for.

da_grat1

122

January 13, 2005 07:57 PM

Does the game provide options such as computer vs human and human vs human?

llvllatrix

Author

340

January 13, 2005 09:48 PM

Quote:
Does the game provide options such as computer vs human and human vs human?

At this point we can still decide what options the game provides. We can do all of these variations without having to change any of the existing code.

I also have a bit more info on the specifics of the sound system. We are going to be using ogg vorbis encoded music. After a bit of research, It turns out that mp3 the mp3 format is patented, which means to commercially release software that uses mp3s you need to pay royalties. Ogg, however is completely free, and will do compressed audio comparable to mp3, mp4, wmf ect.

I've been thinking on the future of our little game engine and I've decided, when it is done, to let anyone use it royalty free. This means that you can commercially release a game developed with this engine without having to pay anything. Currently I dont think any game engine like this exists. I think this type of release would be a great advantage to the development community. What do you guys think?

We should also give our engine a name. Any ideas?

Will post later,
- llvllatrix

wcm4Him

122

January 14, 2005 12:09 AM

Quote: Original post by llvllatrix
I've been thinking on the future of our little game engine and I've decided, when it is done, to let anyone use it royalty free. This means that you can commercially release a game developed with this engine without having to pay anything. Currently I dont think any game engine like this exists. I think this type of release would be a great advantage to the development community. What do you guys think?

We should also give our engine a name. Any ideas?

Will post later,
- llvllatrix

Yes that would be great, I can't tell you how many times i've looked for an engine to use, look over, or learn from and come to find that every one that I come across you have to pay for. So I think that by making ours free would be a great idea, I'm sure it would be good help to the community if we did this.

As far as a name goes, how do you feel about using your forum name (llvllatrix) as the name for it? I think that would sound cool, but its your name so its up to you if you want to use it, It's just the first thing that came to my mind. :D

Later.

How to program a chess: a forum based tutorial

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