Wow, some of the distortions at the end of the article are really mind bending... For simpler fisheye and defisheye effects, I wrote this web based tool a few

Wow, some of the distortions at the end of the article are really mind bending... For simpler fisheye and defisheye effects, I wrote this web based tool a few years ago which some may find useful! https://jywarren.github.io/fisheyegl/example/ https://jywarren.github.io/fisheyegl/example/