Buzz #15 09 июля 1998

PC

3D FX (PC) - 3D accelerator - as he did on the PC.

                                                           D-Man

(C) MELTED SNOW, 1998


             3D-accelerator. How this is done on a PC.

            --------------------------------------

  Accelerator (the accelerator) is a set
Part of the video card or a specially designed card for
performing different operations on work over the image. When
This significantly reduces CPU utilization, resulting in a 
significant acceleration is achieved in the work (depending on 
accelerator and applications from 20-30% to several tens of 
times). Very conditional accelerators can be divided by 
targets: accelerator graphics (line drawing, polygon fill 
color, etc.) are generally integrated into all modern boards; 
Accelerators animation (support MPEG, video scaling, etc.); 
three-dimensional graphics accelerator - contains a set of 
standard tools not only for acceleration, but also change the 
image, taking into account all possibilities of 3D. 

  The effects that get in the 3D-accelerator:
 Alpha-blending - alpha blending. Texture mapping with different
the alpha parameter - the level of transparency. Ability to 
correctly reproduce the overlapping textures.  Anti-aliasing - 
smoothing the contours of objects, eliminating the "Jaggies" 
forms.  Bi-linear filtering - the two-line filtering. The color 
of each pixel is determined by interpolating the four adjacent 
colors. Delivers increased image quality textures.

 Bus-mastering - control of the bus. Allows the board directly, 
without involvement of the central protsesskra access system 
memory, saving computer resources. Significantly increases the 
speed processing of graphics data. Requires the installation of 
the slot, supporting management.  CCIR-601 - digital television 
standard that specifies the format frame rules for converting a 
standard analovogo video (NTSC, PAL, SECAM) to digital signals, 
the encoding method tsidrogo video.  Color dithering - 
compressing palette that will play full-color images in a lower 
color depth (8 and 16-bit).

 Color key - the color code. Parameter characterizing the change
color pixel, depending on its remoteness.
Contributes to a more realistic image.
 DAC (RAMDAC) - (Digital-to-Analog Converter) converter,
forming an analog RGB-signal to the monitor from a digital
representation of pixels. The rate of its work primarily
depends on the frequency of updating computer screen.
 Depth cueing - the effect of simulating the depth of the image 
by reducing the brightness of more distant elements.  Double 
buffering - Double buffering. In memory instead of one 
identifies two areas in which formed the image frame screen. 
Reading the content comes from that part of the buffer where 
the frame is fully formed, which increases the smoothness of 
playback (especially important for video clips).  EDO DRAM - 
memory with enhanced access, which has the lowest rate from all 
types of memory, but also the cheapest. EDO DRAM installed on 
your video card has a higher rate than similar memory for 
motherboards.  Fogging - aliasing mist to distant osekty.Ne 
only makes the image more realistic, but a few offloads 
accelerators obobrazhenii 3D-graphics.  Frame buffer - a frame 
buffer. Memory area, which forms the screen image.  Gouraud 
ahading - Gouraud shading on. Calculation method, which 
provides a smooth change of color of the surface in simulated 
light source space. Unlike the flat paint provides a more 
realistic image, but poteblyaet more resources.  MDRAM - 
multibankovaya memory based on technology for chips with 
high-bit disk access. For 128-bit access enough only 2Mb of 
memory instead of 4Mb for other species. May built up in small 
volumes.  MIP-mapping - saving multiple texture size to speed 
up the imposition of changing the geometric dimensions of the 
three-dimensional surface.

 Perspective corrected texture mapping-texture mapping with 
perspective correction. One of the most important functions for 
three-dimensional accelerators. Provides the correct 
reproduction of textures at different spatial positions basics 
overlay.  RGB - the color format of the image signal formed by 
the video card to monitor PC.  SGRAM - Synchronous Graphics 
Memory. The most modern form Memory is relatively cheap, with 
the highest rate of access works in contrast to other species 
at a frequency of 100 MHz. Videoanalog widely used by SDRAM.  
Texture - texture. The image used for drawing on 
three-dimensional surface.  Tri-linear filtering - the 
three-line filtering. The color of each pixel is determined by 
interpolating the colors of eight contiguous. Provides the best 
image quality of textures.  Video scaling - scaling of the 
video. Correct reproduction of the video in a window of varying 
size.  Video texture - visual textures. Use as textures on the 
surface of the digitized video.  VRAM - (Video-RAM) two-port 
(allowing access the data simultaneously video processor and 
DAC) video memory. On average, 2 times more expensive than EDO 
DRAM, but faster. At the moment supplanted by fast single port 
memory SGRAM.  WRAM-(Windows-RAM) dual port video RAM, which 
has a 50% higher than the VRAM access speed, as well as maps 
and the Gulf ki rectangular areas. Used in high-power adapters.

 X / Y interpolation - X / Y interpolation. Approximation of 
color picture elements with an increase in the size of the 
video playback window. In the absence of this function 
accelerator image has a characteristic block structure.

 YUV - the encoding method of color signal component signal
luminance (Y) and Chroma signals U and V, used in
video equipment and video clips used in MPEG.
 Z-buffering - Z-buffering is essential for 3D-accelerator 
function. For each picture element is stored coordinate of the 
"depth". In accordance with its value of two elements, 
superimposed on each other, is depicted next to the plane of 
the screen. 

  In the computer market PC-iron at the moment appears
all sorts of 3D-accelerators. The most preferred of
They are the ones that are made on the Voodoo Graphics chipset
/ Voodoo2 company 3Dfx Interactive, Inc. (Eg, Diamond Monster
3D / Monster 3D II). Also not bad are the following boosters: 
Matrox Mystique / Mystique 220; Matrox Millennium / Millennium 
II; ATI XPERT @ PLAY / XPERT @ WORK/3D Pro Turbo PC2TV; ASUSTek 
3DexPlorer-V3000 / AGP-V3000. In addition, the accelerator can 
be as accessories (Add-on) to the graphics card and installed 
in an additional expansion slot, and be most video card with 
built-in set of specialized chips (Chipset). The first group 
includes such accelerators as Diamond Monster 3D and Matrox 
m3D. The second group - Diamond Stealth II (recommended only 
for games) and NIMBER NINE Revolution 3D "Ticket to Ride" (the 
most expensive and fancy card). Selecting the type of card 
depends on what you're going to do. If this is the 3D-games, 
it's better to buy Add-on, then to not be problems with drivers.


  You should only add that despite the power of even the most 
expensive accelerators, they are not able to completely 
replicate all light and tsvetoeffekty which can easily create a 
"naked" Amiga.