1. A method, comprising: a. for each scan line in a raster: storing leftmost pixels of a primitive to be rasterized in a first FIFO (first-in-first-out); and storing rightmost pixels of the primitive in a second FIFO; b. determining leftmost tiles and rightmost tiles for each scan line region based on the leftmost pixels and the rightmost pixels, each tile including a grid of pixels; c. starting at a tile having a topmost vertex of the primitive, processing a given tile by: i) interpolating a first pixel parameter value on a given scan line within the given tile based on a base parameter value for the given tile, the base parameter value being based on an initial base parameter value corresponding to a base parameter value in the tile having the topmost vertex; and ii) interpolating any subsequent pixel parameter values for the given scan line in the given tile based on the pixel parameter value for a previous horizontal axis value; d. steering to a number of next tiles to the left of the given tile, and to the right of the given tile, and processing each next tile until the leftmost tile and the rightmost tile in the given scan line region has each been processed; e. steering to a next tile in a next scan line region from the given tile; and f. repeating c(i)-f until the adjacent tile does not have any valid pixels.