A sort of rubbish cube map distorter

If you have built a skybox flat on 6 planes, Gnomonic will sort of distort it.

Turns this:
Into this:

As you can see, there are some artefacts at the join between the top and bottom faces. I've sunk too much time into this already :)

The process uses javascript canvas, so the finished image will appear when it's done, and you can right click > save image.