2.6.2. Anti-aliasing

The GPU supports 4x Full Scene Anti-Aliasing (FSAA) using rotated grid multi sampling with negligible performance loss. Figure 2.3 shows a 2x2 grid layout, with the sample pattern rotated, to avoid any horizontal or vertical axis alignments.

Figure 2.3. Rotated Grid algorithm


When activated, anti-aliasing is performed by calculating a coverage factor. This is achieved by checking how many of 4 sub-pixel locations within a pixel is covered by a polygon. The color of the pixel is a function of the color of the polygon and the coverage factor.

You can enable 4x FSAA by selecting an EGL configuration with EGL_SAMPLES equal to 4 when the graphics context and rendering surfaces are created.

In addition to 4x FSAA, the Mali GPU supports 16x FSAA with a performance cost for pixel processing of approximately four-times that of 4x FSAA.

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