Refactor 2022 #3

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All of the images in this blog, until recently, use a process called anti-aliasing. See https://en.wikipedia.org/wiki/Supersampling

If, for example, you want to draw a line on the computer screen, you could calculate which pixels are on the line and light them up. This almost works. We naturally think of a pixel as a zero-dimensional point, and the line as one dimensional. But a line needs some width, or it would be invisible, and a single pixel covers some small area of the display. A typical monitor has about 100 dpi, so a pixel is actually a 0.01 inch x 0.01 inch square. The pixels are very small, but if you build a diagonal line out of these square pixels, you will still see the corners of the individual pixels. The line looks jagged.

These edge pixels are not entirely on or entirely off the line. The line covers some intermediate portion of the pixel. A better way to draw these pixels is to consider the partial coverage. If the line covers 30% of the pixel, then give the pixel a blend of 30% the line color and 70% the background color.

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