13
Accumulation Buffer Algorithm
Allows us to successively render multiple scenes and
have them additively blend as we
go. Each image ends up with an equal weighting of 1/n, where n is the number of samples taken.
(Appendix A in project 2 handout)
Let "canvas" and "temp" be 24-bit
pixel arrays. Let "polygon color" be a 24-bit color unique to each polygon.
1 clear canvas to black;
2 n = 0 (number of samples taken so far)
3 for (i=1; i<=s; i++) (for s subpixel positions)
4 for (j=1; j<=t; j++) (for t fractional frame times)
5 clear temp to black
6 n = n + 1
7 for each polygon
8 translate vertices for
this subpixel position and fractional frame time
9 for each pixel in
polygon (using your scan converter)
10 temp color <--
polygon color
11 for each pixel in
canvas
12 canvas color <--
canvas color + temp color
13 canvas color <-- canvas
color / n
14 convert canvas to 8x3 bits and
display on screen (by exiting from your rasterizer)