ABSTRACT
This chapter explores a use of discontinuity edge overdraw for antialiasing simple objects on 3D-capable mobile devices. The essence of this technique is to render a "smooth" line on top of aliasing primitive edges in order to cover the aliasing edge. The founding observation of was that aliasing in 3D scenes appears mostly at geometric silhouette edges and crease edges, and so only pixels along these lines require antialiasing. As these boundaries can be described as lines, and since line smoothing is widely available in hardware, aliasing can be reduced by rendering smooth lines on top of the aliasing edges. When rendering lines to cover the detected aliasing edges, "over" alphablending is applied, and depth buffering is used to achieve correct occlusion. Lines and triangles are rasterized fundamentally differently: while triangles generate fragments where a fragment center is contained within the triangle, lines generate fragments where they pass through a "diamond" centered around the fragment center.
