Userfull commands: 

r_drawentities 0
bind p "screenshot"
demomap map2.md2

keys.c: Mapped the '*' key to screenshot command since I didn't have it in macosx
	if (key == '*')
	{
		if (down)
			Cmd_ExecuteString("screenshot");
	}



C has no namespace so method names are prefixed by domain of activity:

    SCR_    Screen                 : Anything related to the screen (refresh, palette, ...)
    CL_     Communication Layer    : Client side code
    V_      View                   : Anything related to the view setting
    R_      Rendition              : Anything related to the rendition phase
    SV_     Server                 : Server client side


    
WinMain
{
    Qcommon_Init
    {
        COM_InitArgv                         // Just grab command line parameters, nothing to see with Microsoft COM
        Swap_Init                            // Setup bigEndian/LittleEndian conversion flags
        Cbuf_Init
        Cmd_Init                             // Register a set of commands via Cmd_AddCommand (cmdlist,exec,echo,alias,wait)
        Cvar_Init                            // Register further commands via Cmd_AddCommand (set,cvarlist)
        Key_Init                             // Set what keys press are monitored. Register further commmands (bind,unbind,unbindall,bindlist)
                        
        ...                                  // Register command(z_stats,error,quit)
        
        Sys_Init                             // Check OS version. Reject win32 "Quake2 doesn't run on Win32s"
        NET_Init                             // Init winsock variables, do not open the connection yet.
        Netchan_Init                         // Init a few variables.

        SV_Init                         
            SV_InitOperatorCommands          // Register further command via Cmd_AddCommand: Notice "load" command associated with  SV_Loadgame_f method
                                             // SV_Loadgame_f ultimately leads to a calls to SV_InitGameProgs, which assign ge variable a value, providing the engine with an implementation (see not about abstraction) (ge contain all the game methods). ge is assigned using Sys_GetGameAPI()
                                            
        CL_Init                              // Check if running as dedicated server.
        {
            Con_Init                         // Init console and register set of commands via Cmd_AddCommand
            VID_Init                         // Grab videos parameters and register set of commands via Cmd_AddCommand
            S_Init                           // Grab sounds parameters and register set of commands via Cmd_AddCommand
            V_Init                           // Grab rendition parameters (crosshair etc...) and register set of commands via Cmd_AddCommand
            M_Init                           // Register all menu parameters
            SCR_Init                         // Grab further rendition parameters and register set of commands via Cmd_AddCommand
            CDAudio_Init                     // Init CD Music player
            CL_InitLocal                     // Grab networl parameters and Register net commands via Cmd_AddCommand
            IN_Init                          // Grab control parameters (mouse/keyboard/joystick ) and register commands via Cmd_AddCommand
            FS_ExecAutoexec                  // Grab autoexec.cfg location, inject following command: "exec autoexec.cfg\n"
            Cbuf_Execute                     // Exec command from buffer "exec autoexec.cfg\n"
        }
    }

    while(1)
    {
        PeekMessage
        TranslateMessage
        DispatchMessage
        _controlfp                           // Set the floating point precision ...
                                             // Question: Why do that for every frames ? Probably because precision is altered during the loop execution.
                                             // Answer: The is no other call to this function. It appears that floating point precision remains the same during program execution.
        Qcommon_Frame
        {
            setjmp                           // Anything bad happen, the program will jump back here.
            Cbuf_Execute
            SV_Frame                         // Server frame
            {
	            
	            if (!svs.initialized)        // If playing over network, using a server somwhere, not the local one
                       return;

                       
                rand ()                      // What the fuck ?
                SV_CheckTimeouts
                SV_ReadPackets
                SV_CalcPings
                SV_GiveMsec
                SV_RunGameFrame
                {
                    ge->RunFrame             // ge variable is a struct game_export_t. It comes from gamex86.dll, and work as an abtraction layer. This is how quake2 mod were programmed, generating a new DLL. Quake2 engine did not see any difference between running id's original content and a fan's mod.
                                             // ge gets assigned in SV_InitGameProgs method from sv_game.c
                }
                SV_SendClientMessages
                SV_RecordDemoMessage
                Master_Heartbeat
                SV_PrepWorldFrame    
            }
            
            CL_Frame                          // Client frame
            {
	             if (dedicated->value)        // If running as a dedicated server, no need to perform the Client frame.
                       return;    
	            
                IN_Frame					//Mouse only, grab pointer
                CL_ReadPackets
                CL_SendCommand
                {
                    
                    Sys_SendKeyEvents ();  // get new key events
                    IN_Commands ();        // allow mice or other external controllers to add commands
                    Cbuf_Execute ();       // process console commands
                    CL_FixCvarCheats ();   // fix any cheating cvars
                    CL_SendCmd ();         // send intentions now

	// resend a connection request if necessary
                    CL_CheckForResend ();
                }
                CL_PredictMovement
                VID_CheckChanges              // Very neat: Allow to change the DLL (ref_soft.dll or ref_gl.dll) on the fly to change the rendering path.
                    VID_LoadRefresh           // This is the function actually performing the switch by redefining GetRefAPI.
                CL_PrepRefresh
                SCR_UpdateScreen
                {
                    //This method supports stereo rendering, up to two "frames" with slightly different POV can be rendered here.
                    for(int i=0 ; i numsurfaces, surf = r_worldmodel->surfaces + node->firstsurface; c ; c--, surf++)
                                            	GL_RenderLightmappedPoly
                                            	{
                                            		if (light is dynamic)
                                            		{
                                            			R_BuildLightMap
                                            			R_SetCacheState
                                            			qglTexSubImage2D
                                            		}
                                            	}
                                        }
                                        DrawTextureChains ();
	                                    R_BlendLightmaps ();
		                                R_DrawSkyBox ();
		                                R_DrawTriangleOutlines ();
                                    }
                                    R_DrawEntitiesOnList            //Rendere explosions, beam, lasers and players
                                    {
                                        //Drawn non transparent things, far to near:
                                        for (i=0 ; i < r_newrefdef.num_entities ; i++)
                                        {
                                            R_DrawAliasModel
                                                GL_DrawAliasFrameLerp    //Models vertices are interpolated lerp style
                                        }
                                        //Drawn transparent things, far to near:
                                        for (i=0 ; i < r_newrefdef.num_entities ; i++)
                                        {
                                            R_DrawAliasModel
                                                GL_DrawAliasFrameLerp    //Models vertices are interpolated lerp style
                                        }
                                    }
                                    R_RenderDlights
                                        for (i=0 ; i < r_newrefdef.num_dlights ; i++, l++)
                                            R_RenderDlight (l);
                                    R_DrawParticles
                                    R_DrawAlphaSurfaces
                                    R_Flash
                                }
                                R_SetLightLevel 
                                R_SetGL2D 
                            }    
                            SCR_AddDirtyPoint
                            SCR_AddDirtyPoint
                            SCR_DrawCrosshair
                        }
                        SCR_DrawStats // Health and Ammo icons 
                        SCR_DrawNet
                        SCR_CheckDrawCenterString
                    
                        SCR_DrawPause
                        SCR_DrawConsole
                        M_Draw
                        SCR_DrawLoading

                        re.EndFrame();
                        
                         //From here we are NOT the rendition DLL anymore.
                    }
                    
                }
                S_Update
                CDAudio_Update
                CL_RunDLights 
                CL_RunLightStyles 
                SCR_RunCinematic 
                SCR_RunConsole
                cls.framecount++;                                                                
            }    
            // Note here a lot of time delta are maintained (all,sv,cl,gm,rf)    

        }
    }
}




















//John Carmack did Not really bother with cache miss and indirection
Little/Big endian function pointer for conversion

Quake2 BSP format(Gold): 
http://www.flipcode.com/archives/Quake_2_BSP_File_Format.shtml
http://jheriko-rtw.blogspot.com/2010/11/dissecting-quake-2-bsp-format.html
RADIOSITY: This article is FUCKING GOOOOLD http://freespace.virgin.net/hugo.elias/radiosity/radiosity.htm !!


Quake2 Model format:
http://icculus.org/~phaethon/q3a/formats/md2-schoenblum.html
10 keyframes per seconds fixed (http://en.wikipedia.org/wiki/Id_Tech_3).

MQuake 2 can be run in both software-rendering and in hardware accelerated mode, for the later you need a OpenGL compatible graphics card in addition to id Softwares official specs below.
Minimum requirements:
A 100% Windows 95/98/ME/NT 4.0/2000-compatible computer system (including compatible 32-bit drivers for CD-ROM drive , video card, sound card and input devices)
Pentium? 90 MHz processor (133 recommended) or higher or Athlon? processor
16MB RAM required for Windows 95/98, 24MB required for all other supported operating systems
Quad-speed CD-ROM drive (600 K/sec. sustained transfer rate)
100% Microsoft?-compatible mouse and driver
25MB of uncompressed hard disk space for game files (Minimum Install), plus 45MB for the Windows swap file
Supports network and Internet play via IPX and TCP/IP

Michael abrash: Quake 2 levels are taking up to an hour to process. (Note, however, that that includes BSPing, PVS calculations, and radiosity lighting, which Iíll discuss later.)
Michael abrash: The most interesting graphics change is in the preprocessing, where John has added support for radiosity lighting;

Tried to build, error found:

winquake.h(26) : fatal error C1083: Cannot open include file: 'dsound.h': No such file or directory

Add to add manually dsound.h reference from DirectX SDK.

Build fine after that.

Starting exploring via the quake2 project:

Just like for Quake 1, WinMain is in sys_win.c

We can find the DLL API acquirment in Sys_GetGameAPI

Main game loop calls method Qcommon_Frame

Abstraction layer in Quake2: Interface design pattern in pure C.

    Rendition now is abstracted, Quake engine doesn't know what is the rendering path, only uses a refexport_t struct to call function pointers. The rendition is still based on BSP/PVS
    According to abrash book, I was expecting Portal mecanisms. PHS (Potentialy Hearable Set), is used for sound sent from server to client. This significantly reduced the bandwidth consumption 
    as the time, allowing multiplayer game to host 32 max players instead of 16.
    
    
    Game content is also abstracted via a ge variable, no more Quake C, people not have to compile a DLL (game86x.dll), type game_export_t. Commercial version of Quake2 loaded game_export_t via pointer to gamex86.dll. But quake2 also shipped with source code to generate 
    a new DLL, enabling fans to produce MODs. 
    
    

    
Command design patterns
Floating point precision alteration at runtime
md2: linear frame interpolation. quake models had 250 faces.  Quake2: Our models run from 400 to 700 with the bosses around 2000 faces.
The explosions are now models.    
Import game_import_t also provides TagMalloc and TagFree for memory managment
Colored DYNAMIC lights (Romero "Masters of doom")    


Piece of history here: R_RenderDlight This is the method responsible of the DYNAMIC LIGHTS BLEND RENDERING. The piece of code that allegibly prompted John Romero to switch Daikatana to use the Quake 2 engine


Question to answer: Does a game.dll can add entities to the list sent to the renderer ?

Sometimes parameters are passed to functions via global variables instead of regular parameter: WTF ?! Is it because of the C/Assembly optimization
portabilty ?


WTF is a bmodel anyway ?
	http://developer.valvesoftware.com/wiki/Source_BSP_File_Format
	A Model, in the terminology of the BSP file format, is a collection of brushes and faces, often called a "bmodel" ??
RLY ??!!

Entities are added and cleared on a per Scene basis (V_ClearScene,V_AddEntity)
CL_AddViewWeapon also calls V_AddEntity



TODO:

		- Find out how the Server's frequency is maintained to 10Hz (time = sv.framenum * 100 msec).
				* Q: Does it mean server time and realtime are not the same ?
				* A: Yes, It does.
				


LIGHTMAPS LOADING:
------------------
Lightmap have 4 mipmapping levels ?(MAXLIGHTMAPS) WRONG: Only textures have 4 mipmap
Lightmap totat byte size is 4 * 128 * 128


From http://www.flipcode.com/archives/Quake_2_BSP_File_Format.shtml
Lightmap Lump 


Static lighting is handled in the Quake environment using lightmaps, 
which are low resolution bitmaps that are combined with the texture 
when rendering a face. Lightmaps are unique to a face (unlike textures 
which may be used on multiple faces). The maximum size for any lightmap 
is 16x16 which is enforced by the BSP creation tool by splitting faces 
which would require larger lightmaps. In Quake 1 lightmaps were limited 
to grayscale, however Quake 2 allows for 24-bit true color lighting.

Lightmaps are applied either through multi-texturing or multi-pass rendering 
and should be multiplied with the texture for a face when rendering.

The lightmap lump contains the data for all of the lightmaps in the world 
stored consecutively. Faces store the offset of their lightmap in this lump 
in the bsp_face structure's lightmap_offset. The actual lightmap data is 
stored in a 24-bits-per-pixel RGB format in a left-right, top-down order 
starting at this offset.

The width and height of a lightmap isn't explicitly stored anywhere and 
must be computed. If max_u is the maximum u component of all of the texture 
coordinates for a face, and min_u is the minimum u component of all the texture 
coordinates for a face (and similarly for the max_v and min_v), then the width 
and height of the lightmap for the face is given by the computation:

lightmap_width  = ceil(max_u / 16) - floor(min_u / 16) + 1
lightmap_height = ceil(max_v / 16) - floor(min_v / 16) + 1

Previous formula is WRONG:  The maximum size for any lightmap is 17x17



VRAM Consomption:
Textures, 12045 KB, 267units
Lightmap textures: 17textures at 128*128: 48Kb/texture = 816KB
Seems the maximum amount of VRAM consumed is 128 * 128 * 128 * 4 (MAX_LIGHTMAPS * BLOCK_HEIGHT * BLOCK_WIDTH * LIGHTMAP_BYTES)


Mod_LoadFaces
	GL_BeginBuildingLightmaps
	for ( surfnum=0 ; surfnum < count ; surfnum++, in++, out++)
	{
		CalcSurfaceExtents
		GL_CreateSurfaceLightmap
		{
			LM_AllocBlock			// Get a texture id from the pre-allocated set
			LM_UploadBlock			// Upload a lightmap texture
			LM_InitBlock
			R_SetCacheState
			R_BuildLightMap
		}
		GL_BuildPolygonFromSurface
	}
	GL_EndBuildingLightmaps ();
	
	
The Quake 2 palette is saved in the file baseq2/pics/colormap.pcx of your Quake 2 installation.  (open it with GIMP, photoshop poops in your shoes and display greyscale)	

OpenGL quake doesn't use GenTextures ? It uses it's OWN textureID tracking because programmed against openGL 1.0: That's why this is used:
#define	TEXNUM_LIGHTMAPS	1024 
#define	TEXNUM_SCRAPS		1152
#define	TEXNUM_IMAGES		1153
#define		MAX_GLTEXTURES	1024


OpenGL renderer is a nice trick. Because there is no palette available, the color switch is incorporated in the lightmap !! The multitexturing hence perform the palette switch AND the lighting !!!



Stats per level: 
base1.bsp 1,991,772 bytes   lightmap:725,910 bytes 		36%

pak explorer: 
pak0.pak    48.000 KB 
./demos:       138 KB
./env:       1.200 KB
./maps:      6.000 KB
./models     7.500 KB
./pics       1.000 KB
./sounds:   28.000 KB
./sprites:   1.000 KB
./textures:  2.200 KB



MEMORY SUBSYSTEMS:
==================

- Surface Stack cs_base allocator (Make a graph showing exponential) // 32bits aligned
- Surface stack for BSP ordering
- Hunk allocator (Hunk_Begin uses virtual Alloc), used to load BSP files, // round to cacheline.
- ZONE MEMORY ALLOCATION (common.c) still here (used to load ressources such as images, sounds and textures. But no usage of tags.
- Discuss the way stack,linked list and no memory is allocate

ADD CVAR for movie generation and command for screenshot


CONSOLE SYSTEM:
===============

		Complex system made of function callback, state variable (cvar), alias.
		The console even features a basic bash style completion system (no listing, first match only)(Cmd_CompleteCommand). This system
		is still capable of completing function, alias or cvar names ;) !
		
		Ability to load a script with C comment capability.
		
		All non client calls are also sent to the server over the network

		FUNCTION SUB-SYSTEM (kernel::cmd.c):
		====================================
		
		Stored in cmd_functions
		
		Linked list, with command name and associated void (*)() function pointer.
		Linear linked list search with strcmp
		
		The function take it's argv and argc from Cmd_Argv abd Cmd_Args global variables.
		
		"cmd" command will be forwared to server via the network
		
		CVAR SUB-SYSTEM (kernel::cvar.c):
		=================================
		
		Stored in cvar_vars
		
		Linear linked list search with strcmp  
		
		To improve performances, some cvar pointer cache cvar lookups (instead of using Cvar_Get every time). This is particularly true in
		the renderer modules, they keep reference to "hand" via a r_lefthand, "gl_lightmap" in gl_lightmap and so on
		
		ALIAS SUB_SYSTEM: (kernel::cmd.c):
		==================================
		
		Stored in cmd_alias
		
		
		
		Note you don't have to use "set" command to set a cvar you can just type its name and new value: Cmd_ExecuteString will try function,alias and cvars


TIME SYSTEM:
============		

- extratime =  sum of last msec.
- extratime is a counter to skip framerate under cl_maxfps


	cls.frametime = extratime/1000.0;		// How much time was elapsed since last frame was renderer as float
	cl.time += extratime;					// Same as cls.frametime, used to send back to server
	cls.realtime = curtime;					// curtime comes from Sys_Milliseconds = time since Quake started
	
	
Netchan still base of networking communication	


TODO:
=====
        - Finish explosing the mipmapping system.
        - Check sound system memory consumption, memory map of Quake2 ?