File

kosa.html

A field of grass and a scythe. Swing it the way it is actually swung — heel first, in an arc across your body — and the grass falls where the blade went. Cut all of it.

3.3 MB · Three.js r170 · WebGL 2 · Needs a connection
Download kosa.html

Save it, double-click it, it runs in your browser. Best with sound and a real GPU.

Kosa is the scythe. You stand in a forty-metre field at six in the evening with the light going, and the job is to cut it. Hold the left mouse button and drag across to swing; walk with WASD. The grass goes down where the blade passed and stays down.

How it works

The scythe is not an animation. It is a rigid body on a spring, held the way the scything manuals describe — left hand on the top grip by the hip, right arm long down the snath — and your drag drives it against that spring. The blade cuts along the arc it actually travels, so a short jab takes a sliver and a long committed sweep takes the whole swath. Walk for a moment without cutting and he shoulders it; reach out to mow and he brings it back down.

A swing that cuts about four square metres is what the field is scored against, and the HUD tracks the percentage down, the wind, and the time of day. Finish and it shows your swings and your efficiency — cut per swing against that reference. Land a full one and PERFECT lights up.

The sky is live rather than a backdrop: sun and moon on a real day cycle, stars, cumulus and cirrus, a twilight belt, and a rainbow when the geometry is right. Cloud shadows track across the field, and every lit material picks up mist and wetness from the same model. The grass is instanced — up to about 56,000 blades near you on the high preset, with cards carrying the distance — and it is anti-aliased with TAA.

Controls

  • Hold the left button and drag to swing. WASD or the arrows to move, Shift to hurry.
  • Esc opens settings — quality, sky, how fast time runs, and the volumes. M mutes the music, N the effects.
  • P for photo mode, H hides the mower, F goes fullscreen.

What it needs

  • A browser with WebGL 2, and a machine with a real GPU for the high preset. It opens on medium and there are three presets in settings.
  • An internet connection: Three.js r170 comes from jsDelivr and the sky's HDRI from Poly Haven.

Credits

The mower is Hendrik the engineer who became a sheep herder by ustoopia, used under CC BY 4.0. Everything you hear is generated in the browser — the pad and bells, the wind, and the birds, frogs and crickets that come and go with the hour.

Other files