The program "neetro" is a demo I challenged myself to make one night when I had
nothing better to do. The idea was to produce a cool mouse chasing fading effect,
without the luxury of color. To make things a bit more difficult, I also decided
to write the demo completely in monochrome text mode...and in x86 assembly.
After a few hours of hacking, success was had. The goal was met by modifying the
VGA font tables with my own precalculated monochrome dithered pattern. This could
then be used to simulate the luminance value of individual "pixels". The pixels
themselves are actually made up of 8x8 font characters. To simulate 64 scales of
gray, the various dither patterns of each "pixel" work to trick your eyes into thinking
the picture on the screen is made up of more than 1 pixel intensity.
The rest of the program was very easy. The program simply renders a small square
at the position of the mouse cursor on each frame. Then, the program takes the current
frame and applies a fade effect. The result is a rather smooth looking cursor trail.
Many PCs appear to have a problem running very old com programs - so there is a
video demo below.
neetro-1.0.asm (Source Code)
neetro-1.0.com (16-bit DOS Binary)