Simulate the Upside Down using an ultrasonic ranging module to light up neopixels!
image/gif - 10.34 MB - 09/19/2017 at 02:16
Updated the software (see GitHub link) to a new implementation.
Due to the inaccuracy and unreliability of the range finder at anything more than a couple of feet, the strip is instead now lit by a strictly-incremented or -decremented value on loop. When the detected position on the range finder is behind the currently lit pixel - i.e., closer to the ranger finder - it starts decrementing the target pixel. It goes back to incrementing once the position is ahead of the target pixel. A set number of pixels adjacent to the target pixel are always lit, as well. Overall, this makes for a much smoother effect!
Distances past ~5 feet are still difficult to "trigger", so I've got some more tuning to do before I'm ready to show off the final product.