可交互的俯视锦鲤池：涟漪、下雨与漩涡

Build an interactive koi pond as a single web page using Three.js and WebGL. Show the pond from directly above: turquoise water with animated caustic light patterns on a tiled pool floor. Add a small floating panel at the bottom where the visitor picks one of four koi varieties, such as orange-white, white, golden and dark-spotted. Clicking the water drops the chosen fish in: a splash appears, turns into expanding ripples, and the koi dives and then swims on its own with smooth, natural body motion and avoidance of other fish. Add water interactions: a rain mode with droplets, a whirlpool that pulls fish and water into a spiral, and ripples that follow the cursor as it moves through the water. Add soft synthesized sounds for splashes, droplets and gentle water ambience, with a mute control. Done means many fish can swim together smoothly in the browser, and every interaction visibly disturbs the water surface.