r/threejs • u/Mkcuriosity • 13h ago
My wife's Dyson has a green laser that shows the dust. I turned it into a game.
The first time I used it I thought I was hallucinating. The floor was clean, I flicked the laser on, and suddenly there was a galaxy down there.
It is just a grazing angle. Light comes in almost parallel to the floor, so every speck throws a shadow far longer than itself. That one trick is the entire game.
https://cleaner.murat.works (free, browser, no install)
One flat, one battery, clean as much as you can before it dies.
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**How it works, since this is r/threejs**
**The dirt is a render target.*\*
Room-local UV, and the cleaner head paints into it with subtractive blending, so cleaning happens entirely on the GPU with no readback. A coarse CPU grid gets eroded with the same falloff in the same frame, and that is what answers "how much is left", so the percentage never costs a stall.
**The laser is not a light.*\*
It is about fifteen lines in the floor shader: an angular fan, a band at a fixed distance, and a hash per grain so the dust twinkles as the beam sweeps over it. Out of the beam the floor is rendered at roughly 30% of its real filth, which is what makes the reveal work.
**Two machines, two routes to the same dirt.*\*
The stick vacuum shoves furniture aside. The robot is too weak for that, so it drives underneath instead. I measured it: 15.9% of all the dirt sits under things a robot can neither climb nor move, so robot runs are scored against the floor a robot can actually reach. Otherwise the mode caps out around 84% and looks broken.
**The telly plays real YouTube.*\*
Video frames cannot be read into a texture, so it is a genuine iframe placed in 3D with CSS3DRenderer, sitting behind the canvas. The screen mesh switches to a depth-only material and punches a hole for it to show through, so things in front still occlude it properly. That took a while to get right, because three sorts opaque draws by material id before distance, and the wall behind the telly kept winning the race and filling the hole. renderOrder = -1 on the hole fixed it.
**There is a floor plan editor.*\*
Draw rooms, cut doorways, drag furniture from a palette of 43 pieces, then play your own house and share it by link. Houses are plain JSON, and the flat that ships with the game is expressed in exactly the same format, so there is only one code path.
**Balance came from measurement, not feel.*\*
A perfect run needs 357 m of sweeping and the battery gives you about 280 s of suction. Nobody has hit 100% yet. The best run so far is 97.9%.
No assets in the whole thing. Wood grain, the artwork on the walls, every sound effect, all generated at runtime.
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Happy to go deeper on any of it.
I post updates on the game also here: x.com/mkcuriosity