Thread: Double Buffering in mode 12h

Mode 12h / 640x480 / 16 color VGA

Hey, Ive been searching for the past two weeks on a good resource for mode 12h vga programming information, but they are very few and far between... I've managed to do pretty well with it so far, but when It comes to drawing large objects on the screen it takes a while (very sluggish).. now, I've read a lot about double buffering and I pretty much get how it works, but when I try to implemtent it... I get choppy black and white blocks.... If anyone knows how to do this it would be a great help.... Now, if you need to see some code I will post some.... thanks in advance

lol, you are right, but It's just another way for me to gain some experience with memory allocation and basic graphics functions, and as for the operating system I use... I mainly use windows XP for most of my deving, but occasionally I use Redhat 9.

Try drawing everything to an off-screen buffer in memory. Then find a way to draw everything between monitor refreshes (I'm guessing check for a vsynch and after one has happened draw as fast as possible).

You will gain 0 experience using that outdated color-plane based crapola mode.

Try something with at least 256 colors like mode 13h.

yah, Frobozz I've thought of trying something like that, and I'll look into it some more, but Bubba.... I have gained a lot of experience form it, I'm not planning on creating any type of meaningful program with it, it is simply for learning, the principles for the most part remain the same... and I'm not planning on sticking with it for long, I've thought about using Vesa instead because of the higher color plane and resolution as you mentioned... the only reason why I chose to play around with with mode 12h is because it was the first thing I was exposed to.

lol, and I can't stand mode 13h

Mode 13h is what rocketed graphics to their current state. Nintendo was all 320x200x256 colors. It was an ingenious color mode and played an important part in the evolution of graphics.

Using 12h will not give you any information regarding how to access modern types of frame buffers. Using mode 13h you will not only gain insight into video memory, but how memory in general works. Accessing mode 13h screen via a pointer is akin to accessing any memory via a pointer be it video memory or memory that holds some other type of numerical data.

Almost all modern frame buffers are a derivative of this:

Code:

struct RGBA
{
   BYTE red;
   BYTE green;
   BYTE blue;
   BYTE alpha;
};

#define RGBA_COLOR  (DWORD)((alpha<<24)+(red<<16)+(green<<8)+(red))

You will learn much with mode 13h.