• Announcements

    • khawk

      Download the Game Design and Indie Game Marketing Freebook   07/19/17

      GameDev.net and CRC Press have teamed up to bring a free ebook of content curated from top titles published by CRC Press. The freebook, Practices of Game Design & Indie Game Marketing, includes chapters from The Art of Game Design: A Book of Lenses, A Practical Guide to Indie Game Marketing, and An Architectural Approach to Level Design. The GameDev.net FreeBook is relevant to game designers, developers, and those interested in learning more about the challenges in game development. We know game development can be a tough discipline and business, so we picked several chapters from CRC Press titles that we thought would be of interest to you, the GameDev.net audience, in your journey to design, develop, and market your next game. The free ebook is available through CRC Press by clicking here. The Curated Books The Art of Game Design: A Book of Lenses, Second Edition, by Jesse Schell Presents 100+ sets of questions, or different lenses, for viewing a game’s design, encompassing diverse fields such as psychology, architecture, music, film, software engineering, theme park design, mathematics, anthropology, and more. Written by one of the world's top game designers, this book describes the deepest and most fundamental principles of game design, demonstrating how tactics used in board, card, and athletic games also work in video games. It provides practical instruction on creating world-class games that will be played again and again. View it here. A Practical Guide to Indie Game Marketing, by Joel Dreskin Marketing is an essential but too frequently overlooked or minimized component of the release plan for indie games. A Practical Guide to Indie Game Marketing provides you with the tools needed to build visibility and sell your indie games. With special focus on those developers with small budgets and limited staff and resources, this book is packed with tangible recommendations and techniques that you can put to use immediately. As a seasoned professional of the indie game arena, author Joel Dreskin gives you insight into practical, real-world experiences of marketing numerous successful games and also provides stories of the failures. View it here. An Architectural Approach to Level Design This is one of the first books to integrate architectural and spatial design theory with the field of level design. The book presents architectural techniques and theories for level designers to use in their own work. It connects architecture and level design in different ways that address the practical elements of how designers construct space and the experiential elements of how and why humans interact with this space. Throughout the text, readers learn skills for spatial layout, evoking emotion through gamespaces, and creating better levels through architectural theory. View it here. Learn more and download the ebook by clicking here. Did you know? GameDev.net and CRC Press also recently teamed up to bring GDNet+ Members up to a 20% discount on all CRC Press books. Learn more about this and other benefits here.
Sign in to follow this  
Followers 0
Vidrohi

Dissecting idTech4

5 posts in this topic

Recently, I realized that even knough I understand many parts of game dev, a complete game and engine and how everything comes together is beyond me, so I looked into a few options and settled on diving into idTech4 to better my understanding of game dev.

 

The problem , however, is that information is very scant. There is no official documentation available and aside from these three sources :

 

http://kotaku.com/5975610/the-exceptional-beauty-of-doom-3s-source-code

 

http://fabiensanglard.net/doom3/index.php

 

and

 

http://www.iddevnet.com/doom3/code.php

 

I have found very little info, I have gotten the game to run from visual studio and stuff , so atleast that is taken care of, but I am unsure of how to proceed with trying to understand this massive codebase.

 

I kinda want to break stuff down and go into one component at a time, maybe starting with AI and character animation, but I cant even find the entry point into these subsystems, can anyone here give me some sage advice ?

 

Thanks

0

Share this post


Link to post
Share on other sites

Generally I would search for WinMain as that will always be the starting point. You may want to look into the Unreal Engine source code, can be downloaded for $19, it's much cleaner code that idtech. For example in the doom 3 BFG source WinMain is in DOOM-3-BFG-master\neo\sys\win32\win_main.cpp, you can set some breakpoint there and work your way through it. You can see from the snippet below where the main game loop starts, this always runs as long as the game is running every other subsytem/call is run inside here.

int WINAPI WinMain( HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow ) {

	const HCURSOR hcurSave = ::SetCursor( LoadCursor( 0, IDC_WAIT ) );

	Sys_SetPhysicalWorkMemory( 192 << 20, 1024 << 20 );

	Sys_GetCurrentMemoryStatus( exeLaunchMemoryStats );

#if 0
    DWORD handler = (DWORD)_except_handler;
    __asm
    {                           // Build EXCEPTION_REGISTRATION record:
        push    handler         // Address of handler function
        push    FS:[0]          // Address of previous handler
        mov     FS:[0],ESP      // Install new EXECEPTION_REGISTRATION
    }
#endif

	win32.hInstance = hInstance;
	idStr::Copynz( sys_cmdline, lpCmdLine, sizeof( sys_cmdline ) );

	// done before Com/Sys_Init since we need this for error output
	Sys_CreateConsole();

	// no abort/retry/fail errors
	SetErrorMode( SEM_FAILCRITICALERRORS );

	for ( int i = 0; i < MAX_CRITICAL_SECTIONS; i++ ) {
		InitializeCriticalSection( &win32.criticalSections[i] );
	}

	// make sure the timer is high precision, otherwise
	// NT gets 18ms resolution
	timeBeginPeriod( 1 );

	// get the initial time base
	Sys_Milliseconds();

#ifdef DEBUG
	// disable the painfully slow MS heap check every 1024 allocs
	_CrtSetDbgFlag( 0 );
#endif

//	Sys_FPU_EnableExceptions( TEST_FPU_EXCEPTIONS );
	Sys_FPU_SetPrecision( FPU_PRECISION_DOUBLE_EXTENDED );

	common->Init( 0, NULL, lpCmdLine );

#if TEST_FPU_EXCEPTIONS != 0
	common->Printf( Sys_FPU_GetState() );
#endif

	if ( win32.win_notaskkeys.GetInteger() ) {
		DisableTaskKeys( TRUE, FALSE, /*( win32.win_notaskkeys.GetInteger() == 2 )*/ FALSE );
	}

	// hide or show the early console as necessary
	if ( win32.win_viewlog.GetInteger() ) {
		Sys_ShowConsole( 1, true );
	} else {
		Sys_ShowConsole( 0, false );
	}

#ifdef SET_THREAD_AFFINITY 
	// give the main thread an affinity for the first cpu
	SetThreadAffinityMask( GetCurrentThread(), 1 );
#endif

	::SetCursor( hcurSave );

	::SetFocus( win32.hWnd );

    // main game loop
	while( 1 ) {

		Win_Frame();

#ifdef DEBUG
		Sys_MemFrame();
#endif

		// set exceptions, even if some crappy syscall changes them!
		Sys_FPU_EnableExceptions( TEST_FPU_EXCEPTIONS );

		// run the game
		common->Frame();
	}

	// never gets here
	return 0;
}
0

Share this post


Link to post
Share on other sites

If you do decide to dissect it, alone or with someone, will you make a blog or news posts about it to increase the net sum of documentation available?

1

Share this post


Link to post
Share on other sites

@rAm_y_  I actually did start there and went as deep as I could, however , after some point you just need someone who knows better to hold your hand for a bit :)

 

@uglybdavis I realize that, however , its those intricacies that I am trying to understand with this attempt, I could very well just mess with my own engine, but I feel like I have reached the limit of what I can learn from it.

 

@FRex I already did , havent gotten very far into it because I got busy with work, but here is the link to my blog :http://strangenessensues.blogspot.com/

0

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0