1. A method of rendering a computer image formed of a plurality of pixels, comprising: identifying, using at least one computing device, a first set of pixels in the image that have properties for which raytracing is advantageous; rasterizing the image, using the at least one computing device, wherein an array of direction vectors is created as part of the rasterizing, the array storing a direction vector from a virtual camera and associated with each polygon vertex in the image; identifying a second set of pixels, using the at least one computing device, wherein the second set of pixels is comprised of those pixels in the first set of pixels which are also in the foreground of the image; and, spawning at least one secondary ray from each pixel in the second set of pixels, using the at least one computing device, wherein the at least one secondary ray is spawned from the respective pixel by using the directional vector associated with the polygon vertices to which the respective pixel relates.