Abstract: A graphics rendering system creates an image based on objects constructed of polygonal primitives, which can generate the perception of three-dimensional objects displayed on a two-dimensional display device. An anti-aliasing operation is applied to silhouette edges of the objects, which are the edges of primitives which are displayed at the perimeter of an object. A silhouette edge can be identified by determining how many times an edge is rendered, with each instance of the rendering of an edge corresponding to the rendering of a primitive that adjoins the edge. An edge that is rendered exactly once is interpreted as a silhouette edge. An example of a silhouette edge is an edge that adjoins one triangular primitive that is viewable and another triangular primitive that is hidden from view by other primitives.

Abstract: A graphics rendering system creates an image based on objects constructed of polygonal primitives. Aliasing effects in the image are reduced by applying an anti-aliasing scheme to the areas of the image representing silhouette edges of the objects. The silhouette edges are anti-aliased by creating anti-aliasing primitives which vary in opacity. These anti-aliasing primitives are joined to the silhouetted edges, and create a region in the image where the objects appear to blend into the background.