generator for performing rasterization in accordance with such embodiments the span generator comprises functionals representing a scissoring box loaders configured to convert the functionals from a general form to a special case form edge generators configured to read the special case form of the scissoring box whereby the special case form simplifies calculations by the edge generators the span generator further comprises sorters configured to compute the intersection of half planes wherein edges of the intersection are generated by the edge generators and a span buffer configured to temporarily store spans before tiling application_number US 4577608 A description triangle intersection of three half planes wherein each half plane is u201c open u201d or u201c closed u201d polygon intersection of a triangle and the clipping half planes shown in fig1 c wherein each clipping half plane is u201c open u201d or u201c closed u201d u201c open u201d half plane a half plane which satisfies the inequality as shown in fig1 d u201c closed u201d half plane a half plane which satisfies the inequality as shown in fig1 d scissoring box a rectangle representing a part of the view port where polygon are actually drawn bounding box a smallest rectangle to fit the intersection of a triangle and the scissoring box extended bounding box.