RetroArch Anti-Aliasing Shaders: A Source-Based Overview

The official RetroArch documentation describes a set of post-process anti-aliasing shaders. According to the documentation, these shaders are useful for smoothing the jagged edges that occur with polygons rendered at non-native sizes. The documentation also notes that the test images it uses do not really show the effects properly in most cases, and that while some shaders—such as advanced-aa—have a visible and pleasant effect on low-res pixel art, these anti-aliasing shaders are mostly paired with high-res content.

Anti-aliasing shaders described in the documentation

• AA Shader 4.0 — A basic anti-aliasing shader with a configurable parameter that allows it to work with greater internal resolution multipliers. | AA Shader 4.0 Level 2 — An enhanced version of AA Shader 4.0 that doubles the radius of pixel analysis. | Advanced AA — An interpolation shader that fills in pixels between upscaled texels; it typically works best at 2x scale factors. | FXAA — A common and fast GPU-powered anti-aliasing algorithm created by Timothy Lottes at Nvidia; it works best on high-res content and is increasingly invasive on lower resolutions. | Reverse AA — An algorithm devised by kdepepo that reduces the effects of anti-aliasing, either natural or artificial, while avoiding many of the haloing problems caused by normal sharpening algorithms; it works best at 2x scale. There is also a 3x scale version for use with other shaders, but there is no preset to use it on its own.

Limitations and caveats

• The documentation states that the test image it uses does not really show the effects of these shaders properly in most cases. | The documentation describes these shaders as mostly paired with high-res content, although some—like advanced-aa—have a visible and pleasant effect on low-res pixel art. | The documentation states that FXAA is increasingly invasive on lower resolutions. | The documentation states that Reverse AA's 3x scale version has no preset to use it on its own.