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

NeHe Productions Affiliates

Started by llvllatrix December 23, 2004 11:09 PM

276 comments, last by da_grat1 19 years, 8 months ago

da_grat1

122

March 11, 2005 12:27 AM

Quote: To be honest, I think the Beowulf code needs to be rewritten because I'm finding it almost illegible.

yeah.. very true.. the code is illegible... No matter how I read it.. still can't understand it.. T_T ... but when I see you modify the main.c .. my brain suddenly open.. b'coz it is more readable... :)

By the way... about the latest source code that you uploaded here.. when I try run it, the only thing I can see is the loading bar.. Is it like that? or something wrong with my pc..

It cannot load the chess board or pieces like in your previous source code before you add the loading bar..

Do I need to add something in order to see the board...?

llvllatrix

Author

340

March 11, 2005 06:26 AM

Quote:
By the way... about the latest source code that you uploaded here.. when I try run it, the only thing I can see is the loading bar.. Is it like that? or something wrong with my pc..

It cannot load the chess board or pieces like in your previous source code before you add the loading bar..

Do I need to add something in order to see the board...?

Right now as a test it basically loads all of the subsystems and then unloads them. Nothing graphical. After we finish the Beowulf dll, we are going to start working on the graphical stuff.

I also spent a good portion of my time yesterday researching chess engines. Unfortunately the way they typically link to the driver app is very nasty (IMO). However, as interfaces go, we have one of the coolest around :).

Will post later,
- llvllatrix

da_grat1

122

March 11, 2005 03:20 PM

Quote: However, as interfaces go, we have one of the coolest around :).

Very true.. lol..
That means.. to load the graphics and move the pieces might take a long time to be done..

llvllatrix

Author

340

March 11, 2005 08:37 PM

Hey guys,

Here's a quick update on my progress. After a few hours of coding I'm finially finished with the first cut of the INTERFACE to the chess engine. Here it is:

#ifndef __BW_H__#define __BW_H__//----------------------------------------------------------------------------////bw.h////Copyright © Rishi Ramraj, 2005// Beowulf DLL Header//----------------------------------------------------------------------------#ifdef __cplusplusextern "C" {#endif//··········································································////    header :: Inclusions//··········································································////··········································································////    header :: Definitions//··········································································//#define DLL_ENTRY __declspec(dllexport)// Beowulf standard typestypedef void					bw_void;typedef int						bw_bool;typedef unsigned int			bw_enum;typedef char					bw_char;typedef bw_char					bw_string [256]	;typedef int						bw_int;typedef float					bw_float;typedef double					bw_double;// Boolean #define BW_TRUE								1#define BW_FALSE							0// Beowulf chess typestypedef bw_char					bw_move[10];typedef signed char				bw_piece;typedef bw_piece				bw_board[64];// Piece Identifiers#define BW_PAWN								1#define BW_ROOK								2#define BW_KNIGHT  							3#define BW_BISHOP  							4#define BW_QUEEN   							5#define BW_KING    							6#define BW_EMPTY   							0#define BW_WHITE_PAWN   					(BW_PAWN)#define BW_WHITE_ROOK   					(BW_ROOK)#define BW_WHITE_KNIGHT 					(BW_KNIGHT)#define BW_WHITE_BISHOP 					(BW_BISHOP)#define BW_WHITE_QUEEN  					(BW_QUEEN)#define BW_WHITE_KING   					(BW_KING)#define BW_BLACK_PAWN   					(-BW_PAWN)#define BW_BLACK_ROOK   					(-BW_ROOK)#define BW_BLACK_KNIGHT 					(-BW_KNIGHT)#define BW_BLACK_BISHOP 					(-BW_BISHOP)#define BW_BLACK_QUEEN  					(-BW_QUEEN)#define BW_BLACK_KING   					(-BW_KING)// Colors#define BW_WHITE						0x0000#define BW_BLACK						0x0001// Enable Modes#define BW_OPEN_BOOK						0x0010#define BW_RESIGN						0x0011// Game States#define BW_GAME_UNSTARTED					0x0020#define BW_GAME_IN_PROGRESS					0x0021#define BW_CHECK						0x0022#define BW_CHECKMATE						0x0023#define BW_STALEMATE						0x0024#define BW_DRAW_REPETITION					0x0025#define BW_DRAW_FIFTY_MOVE_RULE					0x0026#define BW_DRAW_LACK_OF_FORCE					0x0027//··········································································////    header :: Structures//··········································································////··········································································////    header :: Class Defs//··········································································////··········································································////    header :: Function Defs//··········································································////// System Management//// bw_init_beowulf// Initialize the Beowulf system. This must be called before any calls to the// system can take effect. This function should only be called once. Returns true // on success, false otherwise. Behaviour is undefined if initialization is // called more than once.DLL_ENTRY bw_bool bw_init_beowulf(void);// bw_deinit_beowulf// Deinitialize the Beowulf system. This function must be called after all// calls to the image system. This function should only be called once.DLL_ENTRY bw_void bw_deinit_beowulf(void);// bw_enable// Enables subsystems defined under Enable Modes above.DLL_ENTRY bw_void bw_enable(bw_enum ena_mode);// bw_disable// disables subsystems defined under Enable Modes above.DLL_ENTRY bw_void bw_disable(bw_enum ena_mode);//// Opening Book//// bw_load_opening_book// Loads the opening book for the Beowulf system. This file contains strategy// for the beginning of the chess game. The system can function without the// file.DLL_ENTRY bw_bool bw_load_opening_book(bw_string path);// bw_reset_opening_book// Unloads the opening book. This is also called by bw_deinit_beowulf().DLL_ENTRY bw_void bw_reset_opening_book(bw_void);//// System Personality//// bw_load_personality// Loads the personality file for the Beowulf system. The system can function // without the file.DLL_ENTRY bw_bool bw_load_personality(bw_string path);// bw_reset_personality// Unloads the personality. This is also called by bw_deinit_beowulf().DLL_ENTRY bw_void bw_reset_personality(bw_void);//// Attribute Manager//// bw_reset_attrs// Resets the system to it's default state (note that this is independent from// the Opening Book and Personality).DLL_ENTRY bw_void bw_reset_attrs(bw_void);// bw_set_white_chess_clock_attr// Sets the total length of white's game in minutes; the length of the// game is the time a player has to achieve a check mate.DLL_ENTRY bw_void bw_set_white_chess_clock_attr(bw_float minutes);// bw_set_black_chess_clock_attr// Sets the total length of black's game in minutes; the length of the// game is the time a player has to achieve a check mate.DLL_ENTRY bw_void bw_set_black_chess_clock_attr(bw_float minutes);// bw_set_max_move_duration_attr// The maximum time a computer player has to make it's move. This// time is overrided by the minimum depth attribute.DLL_ENTRY bw_void bw_set_max_move_duration_attr(bw_float minutes);// bw_set_min_search_depth_attr// Sets the minimum search depth. When the computer is computing a// move it builds a tree of possible moves and expands that tree to// produce better results. The minimum search depth reprents how many// moves ahead the computer should search at a minimum.DLL_ENTRY bw_void bw_set_min_search_depth_attr(bw_int depth);// bw_set_white_skill_attr// Skill level of the white computer opponent. This is an integer // between 1 and 10, 10 being the strongest.DLL_ENTRY bw_void bw_set_white_skill_attr(bw_int skill);// bw_set_black_skill_attr// Skill level of the black computer opponent. This is an integer // between 1 and 10, 10 being the strongest.DLL_ENTRY bw_void bw_set_black_skill_attr(bw_int skill);// bw_set_hash_size_attr// Size of the hash table used by the AI. Larger sizes produce// faster computations. Hash Table Size is 2^size kb.DLL_ENTRY bw_void bw_set_hash_size_attr(bw_int size);//// Game manager//// bw_begin_game// Resets the current state of the game to a new one. This must be followed// by an accompanying bw_end_game() call.DLL_ENTRY bw_void bw_begin_game(bw_void);// bw_end_game// Resets the current state of the game to a new one. This must be follow// an accompanying bw_begin_game() call.DLL_ENTRY bw_void bw_end_game(bw_void);// The following game functions should be called in the main game loop:// bw_ai_ponder_game// An optional call which lets the computer think about its next move while// it's opponent makes their move. This should be called before a call to // bw_move_game or bw_ai_move_game.DLL_ENTRY bw_void bw_ai_ponder_game(bw_void);// bw_move_game// Posts a move to the current side. Returns false if the move is illegal.// This function also returns false if the current game state is not playable.DLL_ENTRY bw_bool bw_move_game(bw_move move);// bw_ai_move_game// Makes the AI preform a move for the current side.DLL_ENTRY bw_void bw_ai_move_game(bw_void);// bw_update_game// Updates the board.DLL_ENTRY bw_void bw_update_game(bw_void);//// Game state information//// bw_get_game_state_info// Retrieves the current game state. Refer to game state definitions above.DLL_ENTRY bw_enum bw_get_game_state_info(bw_void);// bw_get_board_info// Retrieves an image of the current board.DLL_ENTRY bw_board bw_get_board_info(bw_void);//----------------------------------------------------------------------------//bw.h//Copyright © Rishi Ramraj, 2005//----------------------------------------------------------------------------#ifdef __cplusplus}#endif#endif //__BW_H__

All I have left to do is the implementation of the game manager and info functions (unfortunately, the hardest implementations to write). After that I'll write a quick test app and post the results.

Will post later,
- llvllatrix

llvllatrix

Author

340

March 11, 2005 08:44 PM

Hey guys,

Here's a quick update on my progress. After a few hours of coding I'm finially finished with the first cut of the INTERFACE to the chess engine. Here it is:

#ifndef __BW_H__#define __BW_H__//----------------------------------------------------------------------------////bw.h////Copyright © Rishi Ramraj, 2005// Beowulf DLL Header//----------------------------------------------------------------------------#ifdef __cplusplusextern "C" {#endif//··········································································////    header :: Inclusions//··········································································////··········································································////    header :: Definitions//··········································································//#define DLL_ENTRY __declspec(dllexport)// Beowulf standard typestypedef void					bw_void;typedef int						bw_bool;typedef unsigned int			bw_enum;typedef char					bw_char;typedef bw_char					bw_string [256]	;typedef int						bw_int;typedef float					bw_float;typedef double					bw_double;// Boolean #define BW_TRUE								1#define BW_FALSE							0// Beowulf chess typestypedef bw_char					bw_move[10];typedef signed char				bw_piece;typedef bw_piece				bw_board[64];// Piece Identifiers#define BW_PAWN								1#define BW_ROOK								2#define BW_KNIGHT  							3#define BW_BISHOP  							4#define BW_QUEEN   							5#define BW_KING    							6#define BW_EMPTY   							0#define BW_WHITE_PAWN   					(BW_PAWN)#define BW_WHITE_ROOK   					(BW_ROOK)#define BW_WHITE_KNIGHT 					(BW_KNIGHT)#define BW_WHITE_BISHOP 					(BW_BISHOP)#define BW_WHITE_QUEEN  					(BW_QUEEN)#define BW_WHITE_KING   					(BW_KING)#define BW_BLACK_PAWN   					(-BW_PAWN)#define BW_BLACK_ROOK   					(-BW_ROOK)#define BW_BLACK_KNIGHT 					(-BW_KNIGHT)#define BW_BLACK_BISHOP 					(-BW_BISHOP)#define BW_BLACK_QUEEN  					(-BW_QUEEN)#define BW_BLACK_KING   					(-BW_KING)// Colors#define BW_WHITE						0x0000#define BW_BLACK						0x0001// Enable Modes#define BW_OPEN_BOOK						0x0010#define BW_RESIGN						0x0011// Game States#define BW_GAME_UNSTARTED					0x0020#define BW_GAME_IN_PROGRESS					0x0021#define BW_CHECK						0x0022#define BW_CHECKMATE						0x0023#define BW_STALEMATE						0x0024#define BW_DRAW_REPETITION					0x0025#define BW_DRAW_FIFTY_MOVE_RULE					0x0026#define BW_DRAW_LACK_OF_FORCE					0x0027//··········································································////    header :: Structures//··········································································////··········································································////    header :: Class Defs//··········································································////··········································································////    header :: Function Defs//··········································································////// System Management//// bw_init_beowulf// Initialize the Beowulf system. This must be called before any calls to the// system can take effect. This function should only be called once. Returns true // on success, false otherwise. Behaviour is undefined if initialization is // called more than once.DLL_ENTRY bw_bool bw_init_beowulf(void);// bw_deinit_beowulf// Deinitialize the Beowulf system. This function must be called after all// calls to the image system. This function should only be called once.DLL_ENTRY bw_void bw_deinit_beowulf(void);// bw_enable// Enables subsystems defined under Enable Modes above.DLL_ENTRY bw_void bw_enable(bw_enum ena_mode);// bw_disable// disables subsystems defined under Enable Modes above.DLL_ENTRY bw_void bw_disable(bw_enum ena_mode);//// Opening Book//// bw_load_opening_book// Loads the opening book for the Beowulf system. This file contains strategy// for the beginning of the chess game. The system can function without the// file.DLL_ENTRY bw_bool bw_load_opening_book(bw_string path);// bw_reset_opening_book// Unloads the opening book. This is also called by bw_deinit_beowulf().DLL_ENTRY bw_void bw_reset_opening_book(bw_void);//// System Personality//// bw_load_personality// Loads the personality file for the Beowulf system. The system can function // without the file.DLL_ENTRY bw_bool bw_load_personality(bw_string path);// bw_reset_personality// Unloads the personality. This is also called by bw_deinit_beowulf().DLL_ENTRY bw_void bw_reset_personality(bw_void);//// Attribute Manager//// bw_reset_attrs// Resets the system to it's default state (note that this is independent from// the Opening Book and Personality).DLL_ENTRY bw_void bw_reset_attrs(bw_void);// bw_set_white_chess_clock_attr// Sets the total length of white's game in minutes; the length of the// game is the time a player has to achieve a check mate.DLL_ENTRY bw_void bw_set_white_chess_clock_attr(bw_float minutes);// bw_set_black_chess_clock_attr// Sets the total length of black's game in minutes; the length of the// game is the time a player has to achieve a check mate.DLL_ENTRY bw_void bw_set_black_chess_clock_attr(bw_float minutes);// bw_set_max_move_duration_attr// The maximum time a computer player has to make it's move. This// time is overrided by the minimum depth attribute.DLL_ENTRY bw_void bw_set_max_move_duration_attr(bw_float minutes);// bw_set_min_search_depth_attr// Sets the minimum search depth. When the computer is computing a// move it builds a tree of possible moves and expands that tree to// produce better results. The minimum search depth reprents how many// moves ahead the computer should search at a minimum.DLL_ENTRY bw_void bw_set_min_search_depth_attr(bw_int depth);// bw_set_white_skill_attr// Skill level of the white computer opponent. This is an integer // between 1 and 10, 10 being the strongest.DLL_ENTRY bw_void bw_set_white_skill_attr(bw_int skill);// bw_set_black_skill_attr// Skill level of the black computer opponent. This is an integer // between 1 and 10, 10 being the strongest.DLL_ENTRY bw_void bw_set_black_skill_attr(bw_int skill);// bw_set_hash_size_attr// Size of the hash table used by the AI. Larger sizes produce// faster computations. Hash Table Size is 2^size kb.DLL_ENTRY bw_void bw_set_hash_size_attr(bw_int size);//// Game manager//// bw_begin_game// Resets the current state of the game to a new one. This must be followed// by an accompanying bw_end_game() call.DLL_ENTRY bw_void bw_begin_game(bw_void);// bw_end_game// Resets the current state of the game to a new one. This must be follow// an accompanying bw_begin_game() call.DLL_ENTRY bw_void bw_end_game(bw_void);// The following game functions should be called in the main game loop:// bw_ai_ponder_game// An optional call which lets the computer think about its next move while// it's opponent makes their move. This should be called before a call to // bw_move_game or bw_ai_move_game.DLL_ENTRY bw_void bw_ai_ponder_game(bw_void);// bw_move_game// Posts a move to the current side. Returns false if the move is illegal.// This function also returns false if the current game state is not playable.DLL_ENTRY bw_bool bw_move_game(bw_move move);// bw_ai_move_game// Makes the AI preform a move for the current side.DLL_ENTRY bw_void bw_ai_move_game(bw_void);// bw_update_game// Updates the board.DLL_ENTRY bw_void bw_update_game(bw_void);//// Game state information//// bw_get_game_state_info// Retrieves the current game state. Refer to game state definitions above.DLL_ENTRY bw_enum bw_get_game_state_info(bw_void);// bw_get_board_info// Retrieves an image of the current board.DLL_ENTRY bw_board bw_get_board_info(bw_void);//----------------------------------------------------------------------------//bw.h//Copyright © Rishi Ramraj, 2005//----------------------------------------------------------------------------#ifdef __cplusplus}#endif#endif //__BW_H__

da_grat1

122

March 12, 2005 04:20 AM

Wow Really great.. llvllatrix... you manage to modify that troublesome code, from unreadable to readable..
Is the game really going to work soon...

llvllatrix

Author

340

March 12, 2005 03:51 PM

Hey guys,

Anyone up for a game of chess?
http://www.eng.uwaterloo.ca/~rramraj/Gamedev/chess_tutorial/src_tree/chess_src.zip

I've basically wrapped the chess engine and used it in a console interface. You should be able to play the computer if you run the beowulf test binaries. Type quit to exit.

In order to convey your moves to the engine you have to use standard chess notation:
http://www.logicalchess.com/info/reference/notation/

Next I'll be using SDL for our window and UI. Have fun with the code :)

Will post later,
- llvllatrix

[Edited by - llvllatrix on March 13, 2005 8:51:32 AM]

Grevian

138

March 12, 2005 08:40 PM

Hey there everyone, Just thought I'd let you know, I ported the beowulf engine to linux, my code SHOULD compile on Linux AND Windows, (I'm waiting for llvllatrix to get back to me about the Windows part)

Please note that for now, all I did was use #ifdef's to make the code compile on linux and probably windows, as well as create a few fairly basic makefiles. and so far, only for the Beowulf specific stuff, I'm working on the rest of it right now, so the rest of the code will still not compile on Linux.

But you can fire up the test file and have a blast :)

find it: http://www.grevian.org/~grey/files/chess_src.tar.gz
MD5 Sum: d23c55479c10b045460cf8fdc7540800

There.

And stay tuned as I poke 11v11atrix repeatedly for not being cross platform friendly... and for having a hard to type nick :P

edit: Ack! only 4 edit's later, I think this post looks OK, gotta get used to this forum, long time reader, first time poster ;)

[Edited by - Grevian on March 12, 2005 9:40:06 PM]

da_grat1

122

March 12, 2005 09:47 PM

Hahaha.. Great llvllatrix.. this is the first time I play it in dos.. :) and first of all, it is very hard to figure out the move.. but after I learn from the website... I am able to play the game... but however, still take time to move the alphabets.. lol...

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..?

Grevian

138

March 12, 2005 09:52 PM

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 :(

How to program a chess: a forum based tutorial

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