mouse LEFT/RIGHT to spin and look left/right. mouse UP/DOWN to go forward/back and look up/down. Press SPACE (and hold for a sec or two) to toggle through the 6 resolution modes. 180x240 is the highest and slowest. 72x96 gives a good balance between resolution and frame rate on my computer. It runs a little faster here: http://phosphorus.github.io/app.html?id=116393151&full-screen=true
Tunnel mapping tutorial here: http://lodev.org/cgtutor/tunnel.html Help on atan2 here: http://edspi31415.blogspot.ca/2013/11/atan2-using-tan-1-and-anglearg-various.html This was used to convert the image into a list: https://dl.dropboxusercontent.com/u/12239448/ScratchTexture/index.html
