Roving Library

A book truck parks in the shade of the trees.

Astra Scenes · a painted scene plus one Phlux rule, simulated live · 256×192 grid · 48-step seamless loop

The rule that makes it move

This is the whole thing. Phluxel runs it on every cell, every step — the animation is what happens when you repeat it. BASE is the painted scene, so the rule reads the artwork instead of its own output and never smears.

// Astra scene. _sx/_sy rescale the 256x192 coordinates to any grid size.
PARAM _motion = 1
PARAM _amount = 0.7
LET _sx = 256/GW
LET _sy = 192/GH
LET _t = {FRAC,TICK*_motion/48}*6.283185307179586
LET _k=(Y*_sy>97 & Y*_sy<128 & X*_sx>52 & X*_sx<159 & BASE.G>BASE.R) ? (.5+.5*{SIN,X*_sx*.07+Y*_sy*.14+_t})*_amount*.3 : 0
A=255
R=BASE.R+(238-BASE.R)*_k
G=BASE.G+(218-BASE.G)*_k
B=BASE.B+(172-BASE.B)*_k

The coordinates are written for the 256×192 canvas this was painted on; _sx/_sy rescale them, so the same rule works on a smaller grid too. Download the script ↓

Make it yourself

1. Open Phluxel, click Browse Starters and pick Roving Library — that loads the painted scene and this rule together.
2. Press play, then drag the _motion and _amount knobs while it runs. You never have to stop and restart.
3. Paint over the scene, or drop the rule on your own artwork — it reads whatever is underneath.
4. Export a seamless loop as GIF, APNG, MP4, a PNG sequence, or a sprite sheet.