The xkcd Now comic[1] is also done server-side. There's an outer image showing day/night cycles which never changes and the part with the map and all the labels

The xkcd Now comic[1] is also done server-side. There's an outer image showing day/night cycles which never changes and the part with the map and all the labels is rotated within this. The server simply has a precomputed set of images for 15 minute offsets, and chooses whichever to render based on the current UTC time. [1] https://xkcd.com/now https://xkcd.com/now