Algorithm for the area subdivision method

Question

Briefly write down the algorithm for the area subdivision method?

Answer 1

Algorithm for area subdivision is as follows:

1) Initialize the area to be the entire screen.

2) Make a PVPL with respect to an area, sorted on z min (that is, the smallest z coordinate of the polygon in the area). Place the polygons in their suitable groups. Eliminate polygons hidden by a surrounding polygon and eliminate disjoint polygons.

3) Execute the visibility decision tests:

a). When the list is empty, setup all pixels to the background color.

b). When there is accurately one polygon in the list and it is categorized as intersecting, then color the polygon and color the remaining  region to the back-ground color.

c).When there is accurately one polygon on the list and it is a surrounding one, color the   region the color of the surrounding polygon.

d). If the area is of pixel(x,y) and neither a, b, nor c exerts, calculate the z coordinate z(x,y) at pixel (x,y) of all polygons on the PVPL. Pixel is then setup to the color of the polygon with the smallest z coordinate.

4) If none of the above mention cases has take place, then subdivide the screen area into fourths. For each and every area, go to step 2.