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

January 27, 2005 11:04 AM

Thank you for explaining it to me.. :)

Keermalec

122

January 27, 2005 01:41 PM

Following Ivllatrix's logic, we could model our chess pieces this way:

// A triangle is composed of 3 verticesstruct mdl_triangle{	unsigned int		vert_index[3];		// Vertex Index numbers};// A chess piece is all one colour and is composed of trianglesstruct mdl_piece{	unsigned char		col[3];			// Material colour	unsigned long int	num_tri;			// Number of triangles	mdl_triangle		*tri;			// Triangles	unsigned long int	num_vert;			// Number of vertices	float			*vert[3];		// Vertices};// A game set is composed of 32 chess piecesstruct mdl_game{	mdl_piece			*piece;				// Chess pieces};

llvllatrix

Author

340

January 27, 2005 06:10 PM

Quote:
Following Ivllatrix's logic, we could model our chess pieces this way:

// A triangle is composed of 3 vertices
struct mdl_triangle
{
unsigned int vert_index[3]; // Vertex Index numbers
};

// A chess piece is all one colour and is composed of triangles
struct mdl_piece
{
unsigned char col[3]; // Material colour
unsigned long int num_tri; // Number of triangles
mdl_triangle *tri; // Triangles
unsigned long int num_vert; // Number of vertices
float *vert[3]; // Vertices
};

// A game set is composed of 32 chess pieces
struct mdl_game
{
mdl_piece *piece; // Chess pieces
};

Exactly :)

llvllatrix

Author

340

January 28, 2005 06:23 PM

Hey guys,

Massive model loading change set comming your way:

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

Enjoy :D I used the milkshape 1.7.3 sdk to write the plugin (I actually just edited one of the examples). To install the plugin (located in the tools folder) simply copy the dll to your milkshape directory and export away.

I think this is probably going to be one of the biggest, if not the biggest single subsystem in our game. I'm going to be spending the next few days writing the tutorial on programming chess logic and taking care of the remaining subsystems. If you have any questions, concerns, comments or queries just post :)

Will post later,
- llvllatrix

da_grat1

122

January 28, 2005 11:32 PM

Do you mean only copy "ms_r3d_exporter.dll" into my milkshape 3d folder? which is located in my program files?

what should I do next after I copy the "ms_r3d_exporter.dll" into my milkshape 3d folder?

When I tried to run the "msPlugIn.dsw" in the tools folder, a message box appeared.. It says "please specify the executable file, executable file name"..

where should I browse for the executable file name?

should I browse and the open the "ms3d" or the "ms_r3d_exporter.dll"?
when i open the "ms_r3d_exporter.dll", it says bad file.. but when I open the "ms3d" there is nothing there..
what should I do...what should I do ? T_T

llvllatrix

Author

340

January 29, 2005 11:09 AM

First let me explain the concept of a plugin...although I'm sure most of you know what one is...A plugin is basically a way to extend the functionality of your program. If you've seen a windows media player visualization then you've seen a plugin. Plugins are typically dll files which are put in a location where the driver program, in our case milkshape, can find them. We are going to be using our plugin to export from milkshape to a format our program can understand (ie the set of model loading classes). I named the format r3d or resource 3d. We can then use the set of classes I wrote to import and draw this format in our opengl window.

Do you mean only copy "ms_r3d_exporter.dll" into my milkshape 3d folder? which is located in my program files?
[/quote

Yup. Remember that you need to have version 1.7.3 of milkshape for the plugin to work.

Quote:
what should I do next after I copy the "ms_r3d_exporter.dll" into my milkshape 3d folder?

Once you have the plugin installed, it appears in the file->export->r3d... menu in milkshape. Click this button and our export code will execute.

Quote:
When I tried to run the "msPlugIn.dsw" in the tools folder, a message box appeared.. It says "please specify the executable file, executable file name"..

where should I browse for the executable file name?

should I browse and the open the "ms3d" or the "ms_r3d_exporter.dll"?
when i open the "ms_r3d_exporter.dll", it says bad file.. but when I open the "ms3d" there is nothing there..
what should I do...what should I do ? T_T

lol, calm down. I remember there was an MIT prof who said "you should never get too sad when your projects break or too happy when they run. They certainly don't feel the same way about you." :D

Basically the only reason you would ever want to "run" a plugin is to debug it. Under normal operation, the driver program calls the plugin. Milkshape, however, is designed not to run plugins in this manner....its a software protection thing. Anyway, you dont need to build and run the plugin because I have alreay compiled the dll for you. If you want to make your own changes to the plugin, simply compile the plugin and copy it over to the milkshape directory.

The stuff you want to look at is in our gl basecode. I have converted all of our assets to .r3d using the plugin and we can now import them into our basecode. See if you can use the classes to draw the entire chess scene :)

Will post later,
- llvllatrix

da_grat1

122

January 29, 2005 01:06 PM

I don't think I can do it... T_T
My milkshape 3d version is expired... T_T
what should i do...
I don't have credit card, so cannot buy this product T_T

llvllatrix

Author

340

January 29, 2005 01:18 PM

lol, you dont have to buy it; I have converted all of our models into the desired format. You should be able to find it in the data section of the gl basecode.

da_grat1

122

January 29, 2005 01:55 PM

but I cannot open the "file->export->r3d" just like u said..
a message box appeared... it says "This version has expired! You cannot save your work anymore.. Please register http..etc"

that means I cannot view the .dll
any other ways to let me view it...

llvllatrix

Author

340

January 29, 2005 03:19 PM

Quote:
but I cannot open the "file->export->r3d" just like u said..
a message box appeared... it says "This version has expired! You cannot save your work anymore.. Please register http..etc"

Well, the only reason we are using the plugin is to convert our ms3d assets into r3d files, which I have already done. Beyond that, the only other reason to use the plugin is to create new r3d models.

Quote:
that means I cannot view the .dll
any other ways to let me view it...

lol, not much to see. Its just a save as dialog box and thats about it. If you really want to create your own assets then you're probably going to have to write an asset exporter from blender or something. It shouldnt be that hard...most 3d modeling programs have an sdk for plugins.

How to program a chess: a forum based tutorial

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