The new 8x, 12x and 16x Anti-Aliasing on GeForceFX
Even while announcing the original CineFX archicture, nVidia stated their intention to introduce new and higher/better AA modes. Specifically 6xAA under Direct3D and 8xAA for both Direct3D and OpenGL were planned, and even a 16x anti-aliasing for the professional-grade QuadroFX. Meanwhile, a few new anti-aliasing modes found their (purely unofficial) way into newer Detonator drivers: 6xS and 8xS in November, and the 4xSS, 6x and 8x modes in January. Given the appropriate drivers and tweaking tools, as our own aTuner, these are available for even Geforce 3/4 based graphics cards.
But which anti-aliasing modes nVidia would make official for GeForceFX, and whether there would be any more, we couldn't tell by these newly discovered modes. Using Detonator version 42.68, as in our Radeon 9500/9700 vs. GeforceFX 5800/Ultra review, no additional modes were available besides those already mentionend.
This changed with the followup 42.74 and 43.45 driver versions. On GeForceFX 5600/5800 these drivers officially support 8x and 16x anti-aliasing under Direct3D and OpenGL, and 6x AA under Direct3D only. According to the driver control panel, the GeForceFX 5200 only supports up to 4x anti-aliasing (and 4xS under Direct3D), yet the higher settings are still available through aTuner.
Investigation of the new modes uncovered a certain quirkiness: Without a doubt the older modes remained unchanged, but the 8x and 16x modes (OpenGL), and the 6x, 8x and 16x modes (Direct3D) nVidia introduced beyond the 42.68 version drivers required further investigation.
But first we need to correct a mistake we made earlier: When using the new FSAA Viewer testing program we discovered that the mode aTuner used to designate as "6xS" (no relation to the driver panel's 6xS) doesn't employ six subpixels, but twelve subpixels. The following screenshot proves this:
This image clearly reveals twelve subpixels per final screen pixel. The subpixels' relative positions are not to be taken for granted because the tool unfortunately centers its display of subpixel masks on a subtexel, thus the results are off for modes combining multisampling and supersampling. Still, the total count of twelve subpixels and their approximate relative positions are clearly indicated by the tool.
The following benchmarks will offer further proof for the more complex nature of this 12x anti-aliasing in comparison with the 6x setting, because 12x is significantly slower than nVidia's 6x. aTuner has now been updated to appropriately name this mode "12x Anti-Aliasing". But how do the AA modes available through aTuner compare to nVidia's official settings?