GPGPU Programming for Games and Science

GPU Computing 133

FIGURE 4.5: A two-dimensional illustration of pixel ownership using the

top-left rasterization rule.

The concept of half-open interval may be extended to triangles in 2D.

Edges are either horizontal (y is constant) or not horizontal. If a triangle edge

is horizontal and all triangle points are on or below that edge, the edge is said

to be a top edge. If a triangle edge is not horizontal and all triangle points in

the rows spanned by the edge are on or right of that edge, the edge is said to be

a left edge. A triangle has one or two left edges but does not necessarily have

a top edge. Similar to the 1D rasterization shown in Figure