Show HN: Motion stereograms (magic eye 3D images)

The low resolution of the stereogram is interesting. If you look at a wall at an angle, you see large steps, rather than an angled surface. Looking into this, it's caused by the fact that the program limits pairs of constrained pixels to integer values. The difference of a single pixel in feature placement has that large an impact on stereoscopic depth perception!

I also added a render mode that uses interpolation to allow constraints between non-integer locations. You can press 4 to see this. It works well (removed the banding), but introduces artifacts as rounding errors are propagated across the screen (Magic Eeye images seem to show these artifacts as well, so I bet the algorithm used for those books takes this approach).