FSAA Quality
Lets take a look at some screenshots of the output with FSAA enabled.
The shots on the left are taken a a resolution of 640x480 and doubled in size to accentuate the intermediate FSAA samples. The image on the right is a close up, four times its initial size.
There appears to be little appreciable difference between the 3X and the 4X shots, however the 3X sample does actually appear to be providing extra samples, while the 2X shots just seem to make things blurrier.
To look at the FSAA sample patterns a little closer we'll use Henrik ‘Basic’ Gustavsson’s FSAA test app, as used in our 3Dlabs Wildcat III & SuperScene Anti-Aliasing article.
Here we can see that there appears to be no extra samples from 2X FSAA, and both 3X and 4X FSAA are increasing the number of vertical samples by 2. From this, and the previous images, it would seem as tough the 2X mode is not actually increasing the number of FSAA samples, but utilising a Quincunx type filter to draw in samples from neighbouring pixels. Both 3X and 4X FSAA appear to actually be increasing the number of samples, but not by the amounts they indicate in that they both appear to be doing 2X FSAA.
The sampling output shown from this application is consistent with SuperSampling.
