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

March 22, 2005 05:52 PM

Quote:
I'm currently setting up some more ui stuff to make our lives a bit easier.

lol.. :) ..great.. I am glad that you worried about our lives aswell..:)

Quote: By the end of today I should have the main game screen and the main game menu done.

wow... we are going really fast this time.. I thought the game menu was supposed to be done on the 23th "23rd - Game menu is complete"
but you said it can be done by today... this is super... that means we could finish this game before 27th.. is that possible to happen llvllatrix? :)

llvllatrix

Author

340

March 23, 2005 01:53 AM

Hey guys,

I'm kinda burnt out right now but I got a lot of progress done on the game. I have the game's state machine setup and it's functioning nicely. I also have some button classes, which I'm currently using to quit the application as well as a nifty loading screen.

I could so a release now but I'm going to hold off until tomorrow. I can get both the main and sub menus out of the way. The main reason I dont want to release now is because its not excatly visually stunning. I know with a bit more work I can get something running that will drop your jaw ;)

Till then,
- llvllatrix

da_grat1

122

March 23, 2005 02:22 AM

Quote: I know with a bit more work I can get something running that will drop your jaw ;)

lol.. I better prepare myself before I run the application.. I really scared that I might drop my jaw.. lol... :) ..that means the main menu almost done.. after that, what is next.. are we going to make the pieces move, I think need to verify the move aswell, eg something like knight can only move in 'L' shape if wrong move is made..error will occur..

da_grat1

122

March 24, 2005 03:25 AM

llvllatrix.. anything for today... can this game really be completed within the time schedule... :)

llvllatrix

Author

340

March 24, 2005 12:42 PM

Hey guys,

Servers went down at waterloo yesterday so I couldnt get this up until just now:
http://www.eng.uwaterloo.ca/~rramraj/Gamedev/chess_tutorial/src_tree/chess_src.zip

Have fun, and more importantly, ask questions :),
- llvllatrix

da_grat1

122

March 24, 2005 02:10 PM

lol... great... the first thing I saw your logo.. :) you appear in the game..

static void draw_new_button_up(const float & left, const float & right, 					    const float & bottom, const float & top){	// Add the caption	game_res_draw_button_text(new_game, left, right, bottom, top);	// Draw the button using standard drawing methods	game_res_draw_button_up(left, right, bottom, top);}static void draw_new_button_over(const float & left, const float & right, 						  const float & bottom, const float & top){	// Add the caption	game_res_draw_button_text(new_game, left, right, bottom, top);	// Draw the button using standard drawing methods	game_res_draw_button_over(left, right, bottom, top);}

I just want to know where did you learn how to create the button or from the above code.. is it everything inside the SDL tutorial... ?

I thought this game can be played already.. lol.. can it be finished before 27... I really want to play it... my hand is itchy already.. :) this game can play with player 2 also right...?

llvllatrix

Author

340

March 24, 2005 05:06 PM

The place where most of the excitement happens is in the context processing code (ctx). This is the place you should look to figure out how to use the engine.

Quote:
I just want to know where did you learn how to create the button or from the above code.. is it everything inside the SDL tutorial... ?

The ui system is a combination of several systems mostly loaded in the resources part of the engine. The resource system has three components. res_ui_controls sets up the drawing area so that we can draw ui to it. res_ui_draw_controls wraps the "current" functions that are used to draw the controls. This way, you can switch between ui drawing routines and still have a fully set of automated classes. res_ui_classes implements the logic behind the button.

Quote:
this game can play with player 2 also right...?

I'm going to leave that up to you guys :) (its not that hard).

Cheers,
- llvllatrix

da_grat1

122

March 24, 2005 05:37 PM

Quote: I'm going to leave that up to you guys :) (its not that hard).

llvllatrix... do mean that there is no functions for player vs player? so that means this game only can play with computer... is it..?

llvllatrix

Author

340

March 24, 2005 05:41 PM

Quote:
llvllatrix... do mean that there is no functions for player vs player? so that means this game only can play with computer... is it..?

lol, it may look that way, but the beowulf chess wrapper is very powerful. It knows who's turn it is. So all you have to do for player vs player is just not call the ai routine to calculate the next move. It should take you about 5 mins to make the beowulf engine do player vs player. You can also do ai vs ai :).

Cheers,
- llvllatrix

da_grat1

122

March 24, 2005 10:54 PM

It knows who's turn it is. So all you have to do for player vs player is just not call the ai routine to calculate the next move. It should take you about 5 mins to make the beowulf engine do player vs player. You can also do ai vs ai :).

in beowulf folder, there is a book.dat.. is that the AI engine.. how did he create the book.. wat is inside the book..
and there is also beowulf.dll..in order to play the game we must include the beowulf.dll.. is that so?
if we want to play player vs player, do we need to use the beowulf.dll aswell?
can't we create our own move..

there is another thing i want to know :) ..when is the game available to play... :) it's on the 27th right? right? :)

[Edited by - da_grat1 on March 24, 2005 11:54:24 PM]

How to program a chess: a forum based tutorial

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