"The world is a dangerous place to live, not because of the people who are evil, but because of the people who don't do anything about it."
- Albert Einstein
I've added an illustration for the GPAA technique with a little more explanation in the demo description.
The wide line is the geometric edge. The arrows show how the neighbor pixel is chosen. The dashed lines shows the value of line equation for that pixel, which is used to compute the coverage value.
