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

da_grat1

122

December 28, 2004 04:22 AM

Great... Now we can start coding...

da_grat1

122

December 29, 2004 12:37 PM

how to create menu for the menu screen using opengl.. I think the menu for the chess should consist of 3 things..(Start or new game, option and exit).. The problem is I have never done this before... :) how to create a button such as new game button where user can click on it.. Is there any tutorial or example for this... I need to complete this project as soon as possible... within 4 months or less if possible :)....

llvllatrix

Author

340

December 29, 2004 01:15 PM

Quote:
how to create menu for the menu screen using opengl.. I think the menu for the chess should consist of 3 things..(Start or new game, option and exit).. The problem is I have never done this before... :) how to create a button such as new game button where user can click on it...

This stuff is all at the top of the tree, so we need to do a few other things before we can create the menu.

Quote:
Is there any tutorial or example for this... I need to complete this project as soon as possible... within 4 months or less if possible :)....

I think we can have it done within a month/month and a half but keep in mind that this is a large project. I'll try to get the details on the clock out today. For now, I've got a bit of a supprize planned...

Will post later,
- llvllatrix

da_grat1

122

December 29, 2004 01:41 PM

Quote: I think we can have it done within a month/month and a half

Wow.. ^o^ .... This is super fast...

Quote: For now, I've got a bit of a supprize planned...

Great... ^o^
I hope the plan will supprize me :)

llvllatrix

Author

340

December 29, 2004 09:08 PM

Ta daa...

Since I'm not doing any of the programming on this project, I might as well do some art :) I thought this might be a cool step up from procedurally generating our assets ;). This is a replica of a board I use at home. Its actually my favorite board because my high school friends and I used to use it all the time, so I guess its a neat tribute...anyway, the art can be downloaded here:

http://www.eng.uwaterloo.ca/~rramraj/Gamedev/chess_tutorial/assets/assets.zip

The art is done in milkshape (www.milkshape3d.com). Later on (when we get to it), I'll provide the code we're going to use to display the pieces (have it already written). The models we use in the game wont animate using skeletal animation (their movement across the board will be animated). I will however, provide an animation sdk that I have written so if you have the time you can try it out. The final render model is just for the purposes of the screenshot above; it wont make it into our game.

Here are some assumptions I made when making the art:
- the scale of one tile (black/white space) is a 1x1 square
- each of the pieces are scaled accordingly
- there is one model for every different kind and color of piece and the board. Why not use the same model for different colors (ie the knight as the base model with different textures to produce black/white)? Later on we may want to consider supporting mods; for example, we could have a lord of the rings chess set and want the fellowship to be white and Saurons forces black. By keeping the models separate, we can preserve this possibility.
- all pieces face towards the positive z axis; this is important because we cant tell, in code, which way the piece is facing. So we assume foreword to be a direction and draw the model, hoping the artist oriented it correctly. Since black is moving forewords in the positive z and white moving forwards to the negative z, we need to rotate the white pieces 180 before we draw them (otherwise the nights will be screwed up).
- the origin is located at the center of the board
- the back rows of each side are parallel with the x axis (important because there must be a white square at corner on the right side of each player)
- the environment (wherever we decide to put the board...ie like in a library or on the beach...) is separate from the board. This way we can swap environments and keep the same board
- the top of the board is 0 in global units

Most of these assumptions are important if we decide to support mods like different pieces/boards/environments (something we can add later, with a bit of effort). What do you guys think our default environment should be btw? I'm thinking a library.

Tomorrow, we will tackle the clock subsystem...might be able to fit in two subsystems for tomorrows post...till then :)

Will post later,
- llvllatrix

da_grat1

122

December 29, 2004 11:04 PM

Wow really nice...
Perfect Design, you are a good designer....
I can't wait until the coding.. lol :)

wcm4Him

122

December 30, 2004 04:18 PM

I think that a library would be a good default environment as well

[Edited by - wcm4Him on January 2, 2005 9:18:18 PM]

wcm4Him

122

December 30, 2004 04:25 PM

llvllatrix, are you the one who runs the nehe website????

llvllatrix

Author

340

December 30, 2004 04:46 PM

lol, no, Jeff Molfee (aka NeHe on the forms) does that...I'm just here regularly :) I owe a big part of my career to this site and since I have a bit of time off, I'm going to help out the community a bit...hope you like my work :)

Cheers,
- llvllatrix

[Edited by - llvllatrix on December 30, 2004 5:46:54 PM]

wcm4Him

122

December 31, 2004 02:11 AM

Quote: Original post by llvllatrix
I owe a big part of my career to this site and since I have a bit of time off, I'm going to help out the community a bit...hope you like my work :)

Cheers,
- llvllatrix

What is your career/job? Are you a designer, artist, programmer, or all of the above? And yes I like your work.

How to program a chess: a forum based tutorial

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