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 17, 2005 12:44 PM

hmm...odd problem...

Quote:
I copied all the contents from openalsdk include folder ("al.h", "alc.h","alctypes.h","altypes.h","alu.h","alut.h","aluttypes.h",
"alutpyes.h") into Microsoft visual C++ include folder.. and the contents of openalsdk lib folder("ALut", "OpenAL32") into MVC++ lib folder..

What ide are you using? The headers should be coppied into a new folder called AL in your include directory like this: 'AL/al.h'. I think however, that the OpenAL install should have done that for you. What happened when you tried to install the OpenAL sdk from Creative?

Some notes on dlls:
You shouldnt have to include any of the dlls in the same path of the program. The ogg/vorbis dlls are statically linked and whomever is trying to run the program should have the openal binaries (OpenAL32.dll) installed on their system (In any folder specified in your system PATH).

Will post later,
- llvllatrix

lazork357

148

January 17, 2005 02:05 PM

Quote:
whomever is trying to run the program should have the openal binaries (OpenAL32.dll) installed on their system

Wouldn't it be better to allow everyone to use this app (regardless of the dll in their system folder), simply by placing the dll in the same folder as the program?

About the others dll's:
I have to include them because I compile my project using Dev-c++, so the libraries I use are not exaclty the same ones included in the package downloadable from the link you gave.
Please excuse me if I'm making such a big mess for such a small thing, but I don't use dll's that much and I've installed OpenAL only once some time ago (not that much, but memory is not my strong point).

Quote:
The headers should be coppied into a new folder called AL in your include directory like this: 'AL/al.h'.

That's precisely what I meant to say...
but I admit it wasn't clear at all in my previous post.
I'd better learn to explain things

llvllatrix

Author

340

January 17, 2005 02:45 PM

Quote:
Wouldn't it be better to allow everyone to use this app (regardless of the dll in their system folder), simply by placing the dll in the same folder as the program?

The advantage of packaging the dll with the program (kinda like what we did for ogg) is that you do not have to install OpenAL to use our program. The disadvantage is that we will not be running the most up to date version. For something like ogg, which is a decoder, I think its fine because we know which sound files we will be decoding (namely our assets). For something like OpenAL, where we don’t know which sound hardware we are running on, I think its best if we use what is on the system. This way we get the most up to date version of the dll, which will hopefully provide the best performance on the machine it is running on.

Quote:
Please excuse me if I'm making such a big mess for such a small thing

No worries :) Its good that you want to discuss it because you usually never get discussions like this in a class (usually its dictated to you). I'm glad you brought it up :D

Quote:
That's precisely what I meant to say...
but I admit it wasn't clear at all in my previous post.
I'd better learn to explain things

lol, I need to work on my communication skills as well :) Communication in a team (which is kinda what this is) is something you really only get exposed to in the workplace. Unfortunately English, imo, is a poor language to reason in. My favorite language is math, followed by c++ :)

Another thing we can do with this thread is guest tutoring:

- Once I finish a part of the code, I'll post with the new source and articles discussing how the code is put together (just like the gamedev articles I posted earlier).
- You guys can then take the articles and source and write a quick post explaining what the code is doing and more importantly why it is doing it, in detail. You should tailor your response to a novice audience (so that it is accessible to everyone in the forum).

Doing things this way would give me more time to concentrate on the source and give you guys a chance to practice your communication skills :) That said, the sound resource component tutorial is up for grabs (feel free to email me at thereisnocowlevel@hotmail.com if you have any questions for your tutorial). Anyone what to go first?

Will post later,
- llvllatrix

da_grat1

122

January 17, 2005 05:05 PM

Quote: The headers should be coppied into a new folder called AL in your include directory like this:I think however, that the OpenAL install should have done that for you.

No.. when i install openAlsdk.. there is no AL folder inside the include folder.. Then I create a new folder called AL just as you said,, and put all the include folder content inside the AL folder..

After that I copied the content of openAl library "Alut.lib" and "OpenAL32.lib" into MVC++ lib folder... Then I compile it.. yeah it works..
but then when i choose the sound from openAl sample sound, It doesn't work T_T

Dos
Test res_snd_sound.h

res_snd_init_sound(); correct result: true, result: true
res_snd_set_listener_orientation_6f successful
res_snd_set_listener_position_3f successful
res_snd_set_listener_velocity_3f successful
res_snd_set_listener_volume_f successful
sound_buffer.load_sound_file(); correct result: true, result: false
sound_source.set_buffer_i(...); successful
sound_source.play(); successful
Press any key to continue

everything look successful.. when i choose the sound such as "ding" sound.. a message box appeared.. It says "console Basecode.exe has encountered a problem and needs to close. We are sorry for the inconvenience." T_T
Did I do wrong? What else did i miss?

llvllatrix

Author

340

January 17, 2005 05:47 PM

Unfortunately the program only plays ogg file. You can either download ogg files (you can get one from the ogg article on gamedev) or you can convert .mp3 ect. to .ogg.

da_grat1

122

January 17, 2005 06:27 PM

Thanks for your explaination.. Now I don't have to worry anymore, All I have to do is to convert the file to .ogg :) and test it..

da_grat1

122

January 18, 2005 08:40 AM

Quote: Next on our to do list is a texture loading resource component.

Great.... :) ... I want to see the chess pieces on the chess board.. :)

Mezmirous

122

January 18, 2005 02:16 PM

I might just take a look into that code, I'de wager I'll develop it with classes..but possibly structs and funcs depending on how things turn out.

Lately I've been having some "issues" with OpenAL ;) But I'm sure they'll be fairly easy to overcome, just one error to get down and I'll be able to get most of OpenAL down. So far it's a pretty straightforward, simple API. The only thing I will have to look into more thoroughly will be OGGs, I hear that is quite a fun time :P

Anonymous

January 20, 2005 06:52 AM

Quote: Original post by llvllatrix
Unfortunately the program only plays ogg file. You can either download ogg files (you can get one from the ogg article on gamedev) or you can convert .mp3 ect. to .ogg.

Here would be a good place for class inheritance, so that the sound system is extensible and support for other audio formats could added later on.

llvllatrix

Author

340

January 20, 2005 12:05 PM

Quote:
Here would be a good place for class inheritance, so that the sound system is extensible and support for other audio formats could added later on.

Thats a good idea :) Using inheritance would let you load your sounds using the appropriate class. Once loaded you could use polymorphism to treat all of your derived classes as the abstract buffer class, abstracting all of the loading away.

The key here is abstraction. You dont want to give anyone using the loading function the responsibility of dealing with how its encoded. The way I get around it...or at least pretend to get around it :)... is by offering a load_sound_file function in the buffer class. The intent is that the load function analyzes the path provided to it and uses the appropriate library to load the file. In this case the only library we have written so far is the ogg library, so we dont have to analyze. Its a bit of a hack, but it works :).

Nj spotting the need for abstraction :D Glad you guys are thinking :)

The next subsystem I am working on is the Image loading subsystem. The basic idea is the user provides a path to an image file and we use that path to create a texture id. I've decided to use the library formerly known as OpenIL (Image Library) to do the job. It supports the following formats (and its Open Source):

.bmp, .cut, .dds, .doom, .gif, .ico, .jpg, .lbm, .mdl, .mng, .pal, .pbm, .pcd, .pcx, .pgm, .pic, .png, .ppm, .psd, .psp, .raw, .sgi, .tga and .tif files.

You can find more about it from:
http://openil.sourceforge.net/about.php

Will post later,
- llvllatrix

How to program a chess: a forum based tutorial

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