newman (04/19/83)
Just a note on terminology. A true "area flooding" algorithm has nothing to do with whether the shape being filled is polygonal or not. In fact, since it is based solely on pixel values in the frame buffer, the outline can be any weird curved shape you want. This is in contrast to a true "polygon fill" algorithm which has nothing to do with the contents of the frame buffer, being derived solely from an input list of vertices. The latter is also a couple of orders of magnitude more difficult to write properly, and requires some heavy hardware to approach real-time. Micros all use the former.
elf (04/19/83)
Uhmm, I beg to differ, but a true "polygon fill" algorithm is no harder than the (more general) area fill algorithm, since the former is easily reduced to the latter. Given a list of polygon vertices which are traversed in a standard way (e.g. clockwise, so the inside is to the right), I can use an area fill algorithm to fill in the polygon by first writing 8-connected lines between the vertices (by using Bresenham's algm, for instance), determining one interior point (easy), and applying area fill. An easier polygon fill is to use a Watkin's-like scan-out, which can probably be done *faster* than an area fill in practice because no pixels have to be read back. Eugene Fium Oops, that's Fiume U of Tarana utcsrgv!elf