next up previous contents
Next: 18.4.2 Minimizing Per-Pixel Calculations Up: 18.4 Tuning the Raster Previous: 18.4 Tuning the Raster

18.4.1 Using Backface/Frontface Removal

To reduce fill-limited drawing, use backface and frontface removal. For example, if you are drawing a sphere, half of its polygons are backfacing at any given time. Backface and frontface removal is done after transformation calculations but before per-fragment operations. This means that backface removal may make transform-limited polygons somewhat slower, but make fill-limited polygons significantly faster. You can turn on backface removal when you are drawing an object with many backfacing polygons, then turn it off again when drawing is completed. Back face removal has the added advantage of eliminating x-fighting problems on objects with sharp edges.

David Blythe