This is a very nice effect. WebGL shaders allow some really cool tricks with 2d images, and the JavaScript required is not too onerous even if you don’t use a library to help.
I used WebGL to crossfade between photographs in different (slightly cheesy) ways.
I used WebGL to crossfade between photographs in different (slightly cheesy) ways.
https://sheep.horse/bostoncrossfade/
Write up:
https://sheep.horse/2017/9/crossfading_photos_with_webgl_-_b...