One Cut Through The Stone

巨劍術 · 一劍開石 — on a cliff in a thunderstorm, a swordsman draws a seven-metre blade out of the air, hangs it point-down over a boulder, and presses both hands down. The stone opens along one plane, the cut glowing white behind the edge, and the two halves lean apart and go over. The boulder is carved at build time into Voronoi cells that sit together seamlessly, and the cleave is a second release mode for that engine: instead of a fracture front spreading from an impact point, cells are released as the EDGE sweeps past their height, and each one inherits a shared toppling motion for whichever side of the plane it is on, plus an opening push that decays with distance from the cut — so only the stone within a hand's width of the blade actually becomes rubble. The heat in the cut is computed from each vertex's resting world position, so a fragment that has already flown off still remembers when it was opened. The sword grows from its own guard (a clip on an along-blade attribute, with a white front at the growth edge) and retracts the same way at the end. Rain is one LineSegments draw whose fall and wind are computed in the vertex shader and wrapped inside a box that follows the camera. Nothing is loaded — no meshes, textures or audio files. A 13 second directed sequence plays on loop. Press F for a free camera, R to replay, space to pause, S for slow motion. Sound is synthesised with WebAudio and wakes on your first click. three.js r185 is bundled; there are no other dependencies.