P5 Rolling Shutter

This is an entry for @sableRaph's weekly creative coding challenge. The theme for this week was "that sketch you never got around to finishing."

This uses slit scanning to time-offset each row of pixels on the screen. I made an earlier version of this in openFrameworks, but it isn't as sharable as a web-based sketch, and there are noticeable discontinuities between rows from differnt frames. To adapt this one for web, I'm using 120-something framebuffers instead of p5.Graphics for performance, and using a shader to blend between rows.