**DosGL**
*2004 (DOS, C & x86 Assembly)*

Versions:
<br>v1.1 - 12 December 2004
<br>v1.0 - 10 December 2004

Graphics library for DOS written in C and Assembly (Borland C++ environment). 
It includes graphic driver based on VESA BIOS Extension (VBE), 
which allows application to switch graphics card into one 
of the high resolution modes exposed by VESA 2.0. While 
regular DOS applications could only display graphics using VGA 
modes like 320x200 in 256 colors, this driver allowed rendering
in resolutions as high as 1024x768 in full 32bpp.

Rendering in higher resolutions, means using higher resolution
bitmaps, and thus requires much more memory than 1MB exposed 
in Real Mode. DosGL solves this problem by using extended 
memory manager (XMM) to store assets in system memory above 1MB.

Final DOS limitation to overcome, is fact that graphics 
card framebuffer in VRAM, is visible to CPU only through 
64KB memory region in Real Mode memory. It's called
"banked mode", with mentioned region being "window"
into cards framebuffer.

This mean that to fill whole screen, DosGL driver needs to 
re-map that window, into different portions of the framebuffer 
multiple times. For example in 1024x768 @ 32bpp mode, 
framebuffer size is equal to 3145728 bytes (3 MB). To 
gradually fill whole frame, it requires switching that 
mapping exactly 48 times each time frame is presented. 

Switching of that mapping is costly and thus DosGL have 
its own framebuffer allocated in XMS memory. This way all 
the graphics operations happen inside of XMS, and 
only finally composed image is being blitted part by part 
from XMS through Real Mode window into actual framebuffer 
for presentation.

Due to above limitations DosGL APIs are limited to blitting
rectangular regions (with and without transparency) from
assets to framebuffer. Loading assets from BMP files,
displaying text using bitmap fonts and mouse driver are
provided as well for convenience. 

This is more than enough to write compelling 2D games.
DosGL was successfully used in few projects at the time,
not only by me but also by my collegues. I consider it
precursor to game engine that I've started developing 
few years later.

Source code, samples and documentation:
<br>[DosGL v1.1](DosGL_final_2.rar)

One way to properly overcome all above limitations would
be to switch CPU into Protected Mode, and use VESA 3.0.
But at that point I got to conclusion that it would be 
better to write new operating system for 386 from scratch,
which would also let me have other missing features like
multi-process support and threads.








<!--
Temporary notes:

In:
H:\@ OLD\DATA CORRUPTED\MOJEGRY\ENGINE

2003/06/25 - Biblioteka XMS 1.0 (Turbo Pascal)
             UXMS.PAS
             H:\@ OLD\DATA CORRUPTED\MOJEGRY\ENGINE\Ksiazka\Biblioteka XMS 1.0
             

     07/10 - UXMSHI.PAS
             Graphics library using VBE and XMS to load images from .TEX file and display them without scaling on the screen.
     07/12 - UTEXTNOR.PAS
             H:\@ OLD\DATA CORRUPTED\MOJEGRY\ENGINE\Ksiazka\Konwerter BMP do BM 1.0

     01/24 - VBE.asm
     06/29 - VBE.PAS
             VESA BIOS Extension library allowing display mode switching between VGA and VESA modes as well as clearing of framebuffer.
             H:\@ OLD\DATA CORRUPTED\MOJEGRY\ENGINE\Ksiazka\Konwerter BMP do TEX 1.0

     07/20 - VBE.PAS
     07/21 - UMOUSE.PAS
     07/22 - DPMI1.PAS (early test of switching DOS into protected mode?)
             H:\@ OLD\DATA CORRUPTED\MOJEGRY\ENGINE

2003/07/12 - Konwerter BMP do BM 1.0 (Turbo Pascal)
2003/07/12 - Konwerter BMP do TEX 1.0 (Turbo Pascal)
2003/07/12 - Konwerter BMP do TEX 1.1 (Turbo Pascal)

2003/10/05 - EMS (podstawowa biblioteka i test alokacji i zwolnienia pamieci)
             H:\@ OLD\DATA CORRUPTED\MOJEGRY\ENGINE\EMS

2003/10/11 - KarolGL (Turbo Pascal)
             Was only dumping VESA info and modes list?

2004/05/30 - VESAC (few C functions operrating on VBE)
             H:\@ OLD\DATA CORRUPTED\MOJEGRY\ENGINE\C

     VBE,      {<- Obsluga VESY (wywolania trybow itd)              }
     UXMS,     {<- Procedury podstawowe do obslugi XMS              }
     UXMSHI,   {<- Procedury do obslugi Vesy i danych w XMS         }
     UTEXTNOR; {<- Procedury dodatkowe do wyswietlania w trybie TXT }


             
ACD OS:

2003/10/06 - First source files in:
             H:\@ OLD\DATA CORRUPTED\MOJEGRY\ENGINE\OS\On.asm



- it was project to pass High School programming class
- after all , all this limitations pushed me into writing ACD OS

DosGL can loading whole, or portion of image 
stored in BMP file, and treating it as either bitmap or sprite. 
When treating it as sprite, application can specify at load
time, which color is representing transparency (in both RGB 
and palette modes). Application can then use those assets
to display them on the screen in whole, or only their rectangular
sub-region. It also provides helper methods for displaying 
text with bitmap fonts, and mouse driver.

Rendering sprites and fonts in those high resolution modes
boiled down to blitting them to the screen, through copying 
memory between XMS and Real Mode memory. Thats where graphics 
card current framebuffer in VRAM, would be mapped into 64KB 
"banked" region accessible by CPU.

Another key component is its use of extended memory manager 
(XMM) to store and manage both: display driver framebuffers 
for selected display modes, as well as bitmap sprites and fonts.

- Rendering in VESA high resolution modes.
- Loading opaque and transparent sprites from BMP
- Displaying sprites or their portions on the screen
- Loading bitmap fonts
- Rendering text using given font on the screen

I wrote it, as I needed simple
way of loading images and displaying them on screen for sprite based
animations in my games. Key feature of this library was support for
high resolution display modes through VESA 3.0. 
-->

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