Source: countdown-with-blob.pov
The Persistence of Vision Ray Tracer, or POV-Ray, is free software that has been around since 1991. The magic of typing a description of something and effectively seeing a “photograph” of it minutes (OK... sometimes hours) later just using maths still seems incredible to me. Of course, a lot has happened in the decades since, with modellers and games engines and GPUs (and now AI seemingly bypassing the whole thing). But I still have a nostalgic affection for POV-Ray and sometimes go back to the old scene description language and play with it just for fun.
I used POV-Ray to produce the images of Planetarium, most obviously in the framing device that presents the hand-drawn artwork (although you can see some in the illustrated solutions too, if you get to the end).
The cover of the Fudebakudo book (including its spider) was rendered in POV-Ray, with the bitmap of the cartoon samurai mapped onto a “flat” cut-out in the scene.
There are more examples of my occasional use of POV-Ray in the scrapbook (tagged #povray), as well as the EveryPolitician bot.