LOSTCIRCUITS

Anti Aliasing

3DLabs emphasizes that competitive solutions are very rigid with respect to the anti aliasing modes supported. There may be some truth to it even though we feel it is adequate to cite Mr. Miyagi saying: "It's in the past". Regardless, with respect to anti-aliasing, the VP-Pro supports the following modes that are fully programmable:

• Super-sample
  Draw everything 4 times bigger and filter down.
• Multi-sample
  Draw multiple samples for each pixel into separate buffers. Depth calculated per sample, color calculated per pixel.
• Accumulation buffer
  Redraw the frame n times and accumulate. Excellent quality with extra effects such as motion blur.
• Computed coverage
  Used by CAD (particularly for lines). Fast but polygons must be sorted

Virtual Memory Management

Conventional graphics adapters can fall back onto the system memory for storage of textures in a contiguous memory subspace called the AGP aperture, however, any other types of data need to be stored inside the on-board local frame buffer. One of the issues that particularly the earlier VIA chipsets had to battle was the problem of creating this "contiguousness" of a fragmented physical memory space by means of the so-called Graphics Allocation Routing Table or GART, which translates discontiguous physical memory addresses into one contiguous logical memory space, even preserving the 4k page size, that is 4096 column addresses per page.

By itself, this mechanism is old news. AGP DMA and DiME have been around for almost 5 years, however, the novelty about the 3DLabs approach is that the AGP aperture can be used to store all data, that is texture AND geometry. In other words, the entire LFB becomes a huge L2 cache and the graphics processor is able to access up to 16 GB system memory. Keep in mind that with a conventional 32bit processor, system memory is limited to 4GB anyway, meaning that in order to take advantage of this feature, it is necessary to run a 64 bit processor. Additional buzz words thrown in are:

• Hardware - optimised demand paging to and from virtual memory / disk
• Solves multiple intractable texture memory problems
• Eliminates fragmentation - texture pages do not need to be contiguous (usually done by GART drivers, see link above)
• Improves performance - pages are only loaded as required (that is standard, too)
• Obscured graphics memory automatically paged out to host (if you can't see it, then it is of no use and can be gotten rid of).

  Next Page:    => Specs and Reality: Stranger Than Paradise =>

  If you enjoyed reading this article and found it useful, please consider making a small donation to LostCircuits.
  Thank you!

  ---

  General disclaimer: This page only reflects the author's personal opinion and assumes no responsibility whatsoever regarding any of the contents or any damages that may occur explicitly or implicitly from reading the contents of this site. All names and trademarks mentioned in this review are the exclusive property of the respective parent companies.
  All contents of this site are protected by international copyright laws. Reproduction of the contents even in parts is not allowed except after written permission by the author and referral to this site.
  Copyright 1998 - 2008 LostCircuits