Anyone using old computers for graphics remembers the strangeness of “flood fill”:

The 1950s and 1960s computers were so sluggish that their consoles with blinking lights were not just for show; the operations were slow enough that you could still follow the lights in real time.

This ceased to be true soon afterwards. The microcomputer revolution temporarily reset some computing progress, but by the 1980s and 1990s more and more things were happening too fast for us to keep up.

But here (this above is Paint in Windows 1.0, and you can try for yourself in a browser!) was one example where you could still see an algorithm working hard. It was mesmerizing and educational, and it was a rare example where perhaps you didn’t mind the computer taking its sweet time. Even messing up like I did above – maybe especially messing up – ended up fascinating to watch.

Wikipedia has examples of a few different flood fill algorithms, which are even more interesting:

A few years later, Minesweeper had a very memorable flood fill, too (also available in a web emulator today):

But by now Minesweeper retired from sweeping mines, and today computers are so fast that it’s hard for me to imagine any flood fill being anything else but flash flood…

…except this is what I just saw in Pixelmator on my Mac:

I don’t know if this is a nod toward a classic flood fill, or just a nice unrelated transition. But I found it genuinely delightful, and it’s fast enough that I would imagine it doesn’t bother pros who need to do it often.

Sometimes it’s nice to see a computer working when there’s a good reason; some apps like banking apps even insert artificial, visible delays after crucial operations, just so that the users feel comfortable knowing their important transaction went through.

But sometimes it’s nice to see a computer working for no reason at all.