Editing Texture mapping (section)

====Other techniques====
Another technique was approximating the perspective with a faster calculation, such as a polynomial. Still another technique uses 1/z value of the last two drawn pixels to linearly extrapolate the next value. The division is then done starting from those values so that only a small remainder has to be divided<ref>{{cite patent
 | inventor-last = Spackman
 | inventor-first = John Neil
 | issue-date = 1998-04-14
 | title = Apparatus and method for performing perspectively correct interpolation in computer graphics
 | patent-number = 5739818
 | country-code = US
}}</ref> but the amount of bookkeeping makes this method too slow on most systems.

Finally, [[Build engine|the Build engine]] extended the constant distance trick used for Doom by finding the line of constant distance for arbitrary polygons and rendering along it.