Displaying 24-bit BMP image files - China DOS Union Forum

Principles:
1. Access the VGA palette registers to get/set the palette:


      OUT &H3C8, Loops
      OUT &H3C9, ASC(MID$(Change$, Loops * 3 + 1, 1)) - 35
      OUT &H3C9, ASC(MID$(Change$, Loops * 3 + 2, 1)) - 35
      OUT &H3C9, ASC(MID$(Change$, Loops * 3 + 3, 1)) - 35

2. Understand the BMP file format.

3. Use the error diffusion algorithm with dithering to draw true-color images. Generally, books on "Computer Graphics" all explain the error diffusion algorithm. The key is this line:


IF PixelBlue >= PixelArray(PixelArraySearch, 1) - ColorDif AND PixelBlue = PixelArray(PixelArraySearch, 2) - ColorDif AND PixelGreen = PixelArray(PixelArraySearch, 3) - ColorDif AND PixelRed = (ColorPalette(Loops, 3) - Movement) AND PixelBlue = (ColorPalette(Loops, 2) - Movement) AND PixelGreen = (ColorPalette(Loops, 1) - Movement) AND PixelRed  3 THEN

What do these things have to do with assembly?
The most important things in learning assembly are learning computer architecture and instruction optimization.
But to write actual programs, what you mainly need is this knowledge:
1. Hardware interface programming. For example, this program accesses VGA registers (you can use the in and out instructions in assembly; QB just turns them into functions)
2. Understand file formats, and know how data is stored, so you can process it
3. To write graphics code, there are professional "Computer Graphics" books you can refer to; algorithm issues are unrelated to the programming language in the first place

As long as you learn those three things above, you can write this kind of program in any programming language. By that point, assembly optimization becomes necessary.

Recommended: "Graphics Programming Black Book (Michael Abrash's Graphics Programming Black Book)," a comprehensive introduction to how to write graphics programs under DOS (2D and 3D) and assembly optimization (real-time rendering):
http://www.netyi.net/Resource/933a25cf-fa0e-4dab-b9d7-e58a0ea8f52e.aspx

[ Last edited by zyl910 on 2006-6-4 at 20:40 ]

Floor2　Kinglion	Posted 2004-02-11 00:00
铂金会员　Posts 1,924　Credits 5,798　From 金獅電腦軟體工作室
Awesome! I admire it! Need to find the gap!

Floor3　jiaking	Posted 2004-03-12 00:00
中级用户　Posts 52　Credits 223
I'm just learning. Can this be compiled and used just like this?

Floor4　xelloss	Posted 2004-03-15 00:00
初级用户　Posts 15　Credits 150
BASIC?? Awesome? This is still my first time seeing someone code this in BASIC. Before, I thought BASIC didn't have this kind of capability!

Floor5　yangyifei	Posted 2004-03-18 00:00
初级用户　Posts 6　Credits 123
BASIC can do a lot more, it's just that our skills have limited it

Floor6　冷石_jasv	Posted 2004-03-19 00:00
初级用户　Posts 27　Credits 182
Hey, I still have to say this: relying on BASIC alone makes it impossible to write really ideal programs; you still have to learn assembly language. Borrow assembly's low-level capabilities, QB or C's convenience for writing and editing programs, and take cues from the structural forms of other visual languages, and under DOS you can still write some pretty good stuff.

Floor1　冷石_jasv	Posted 2003-11-13 00:00
初级用户　Posts 27　Credits 182

Floor7　zyl910	Posted 2006-06-04 20:35
中级用户　Posts 126　Credits 282
Principles: 1. Access the VGA palette registers to get/set the palette: OUT &H3C8, Loops OUT &H3C9, ASC(MID$(Change$, Loops * 3 + 1, 1)) - 35 OUT &H3C9, ASC(MID$(Change$, Loops * 3 + 2, 1)) - 35 OUT &H3C9, ASC(MID$(Change$, Loops * 3 + 3, 1)) - 35 2. Understand the BMP file format. 3. Use the error diffusion algorithm with dithering to draw true-color images. Generally, books on "Computer Graphics" all explain the error diffusion algorithm. The key is this line: IF PixelBlue >= PixelArray(PixelArraySearch, 1) - ColorDif AND PixelBlue = PixelArray(PixelArraySearch, 2) - ColorDif AND PixelGreen = PixelArray(PixelArraySearch, 3) - ColorDif AND PixelRed = (ColorPalette(Loops, 3) - Movement) AND PixelBlue = (ColorPalette(Loops, 2) - Movement) AND PixelGreen = (ColorPalette(Loops, 1) - Movement) AND PixelRed 3 THEN What do these things have to do with assembly? The most important things in learning assembly are learning computer architecture and instruction optimization. But to write actual programs, what you mainly need is this knowledge: 1. Hardware interface programming. For example, this program accesses VGA registers (you can use the in and out instructions in assembly; QB just turns them into functions) 2. Understand file formats, and know how data is stored, so you can process it 3. To write graphics code, there are professional "Computer Graphics" books you can refer to; algorithm issues are unrelated to the programming language in the first place As long as you learn those three things above, you can write this kind of program in any programming language. By that point, assembly optimization becomes necessary. Recommended: "Graphics Programming Black Book (Michael Abrash's Graphics Programming Black Book)," a comprehensive introduction to how to write graphics programs under DOS (2D and 3D) and assembly optimization (real-time rendering): http://www.netyi.net/Resource/933a25cf-fa0e-4dab-b9d7-e58a0ea8f52e.aspx [ Last edited by zyl910 on 2006-6-4 at 20:40 ]