3D graphic card info

The 3D graphic card requires much more memory than the 2D graphic card because its memory architecture is considerably different..

While a 2D graphic card only require one memory area to store ist data the 3D graphic card is using 3 specific video memory bank. The 3d graphic card memory area are named as following:

* The front buffer (required to store the image being displayed)
* The Back buffer (required to store the next image being processed)
* The Z buffer (required to store the 3rd dimension information)

Each of these buffer has to store the same color information as they are required by the 2D graphic card video memory so if for instance we were using the 16-bits color mode then each of these buffer will have to store 2 bytes for each pixel displayed on the screen for a total of 6 bytes by pixel.

Again, this can be expressed by the use a very handy formula which we will use to know how much video memory will be required for a given screen resolution and color depth under a 3D environment.

First we must determine how much bytes will have to be stored into each buffer for a given mode to know which multiplication factor we will have to include into the formula. The multiplication factor is calculated by dividing the number of bits of the color mode by 8 and this result must be added for each of the buffers

Supposing we would like to use the 24-bits color mode (16.7m colors) we will have 24/8 = 3 bytes to be stored in each of the buffers and because there are 3 buffers each storing 3 bytes each the multiplication factor will be 9 for the 24-bits color mode

now suppose we will use the 1024 X 768 screen resolution to complete the formula;

M3D = 9 X (1024 X 768) or simply M3D = 9 X 786,432

which is giving a rounded value 7.08mb, so the nearest memory size allowing this 3D color depth and screen resolution mode will be a 8mb memory bank.

Now, to be sure there will be no mistakes lets make another try and this time we will use a color depth of 8-bits (256 colors) with a screen resolution of 800 X 600.

like in the first example we will calculate the multiplication factor so we have (number of bits of the color mode = 8 which we will divide by 8 for a result = 1) then the multiplication factor will be 1 + 1 + 1 = 3 because there are 1 byte to be stored in each of the 3 memory buffers

so using the formula we will have M3D = 3 X 800 X 600 = 1.44mb which tell us that we will need at least 2mb of video memory installed on the graphic card circuit board to use the 800 X 600 screen resolution with a color depth of 8-bits under a 3D environment..