ATI Radeon X1800XL + FSAA

Now that we have covered the ATI Radeon X1000 series in-depth under Linux, we are back today with yet another look at the X1800XL but this time it comes in form of looking at Full Scene Anti-Aliasing. While premiering with the ATI Radeon X1000 series was new adaptive anti-aliasing and transparency super-sampling, these abilities have yet to be touched by the Linux 8.24.8 display drivers. This situation is similar to NVIDIA and them having yet to introduce their new Anti-Aliasing modes with their GeForce 7 series. Even so, today we are going to be looking at the Full Scene Anti-Aliasing performance and results within Linux using the X1800XL. For those that have never tampered with Anti-Aliasing, it is a technique of over-sampling each pixel to achieve a more realistic image by removing the jagged edges, or "jaggies".

While ATI's Linux Control Panel does not support controlling these Full Scene Anti-Aliasing (FSAA) options, the aticonfig utility is able to handle this task quite well. The FSAA options are listed below, which include enabling the technique as well as setting the number of FSAA samples per pixel. In addition, there is the FSAA gamma correction and FSAA Multi-Sample Positions; however, in this article we will simply be altering the FSAA samples.

aticonfig --help

FSAA Options:
  --fsaa={on|off}
        Enable/disable full scene anti-aliasing.  Enable this option to enhance
        photo-realism in 3D rendering.  Disable it to get the most accurate 3D
        image.
  --fs, --fsaa-samples={off,0,2,4,6}
        Set the number of FSAA samples per pixel or 2, 4, 6.  off is the same
        as setting 0 samples.
  --fsg, --fsaa-gamma={on|off}
        Enable/disable FSAA gamma.
  --fmsp, --fsaa-ms-positions=x0,y0,x1,y1,x2,y2,x3,y3,x4,y4,x5,y5
        Change the FSAA Multi-Sample Positions for x0,y0 to x5,y5.  You must
        specify exactly 12 real number values separated by commas.

With FSAA already enabled, the FSAA samples per pixel can be altered using aticonfig --fsaa-samples=2. All this simply does is alter the X configuration with the options of FSAAEnable and FSAAScale into the fglrx device section. As warned after applying the command (Warning: Option 'FSAAScale' doesn't affect running session), the changes will not be taken into effect until restarting X.

Section "Device"
	Identifier  "ATI Graphics Adapter 0"
	Driver      "fglrx"
	Option	    "FSAAEnable" "on"
	Option	    "FSAAScale" "2"
	BusID       "PCI:5:0:0"
EndSection

To get a better understanding for the effects of ATI Full Scene Anti-Aliasing, on the following page are several screenshots we have taken that demonstrates FSAA at each of the different sample values -- 0 (Off), 2, 4, and 6. The graphics card used was an ATI Radeon X1800XL 256MB with the 8.24.8 display drivers.