LongCat 2.5 Preview · Three.js

Build a GPU-accelerated fluid simulation in a single HTML file using WebGL, no external libraries. Dragging the mouse or a finger should push colorful dye through the fluid, with a soft glow. Make it look stunning and run smoothly.

Build it as a self-contained index.html in the current directory, with WebGL/WebGL2 shaders you write yourself; no libraries and no CDNs; interactive with mouse or touch input. You may serve it locally and open it in headless chromium (/usr/bin/chromium, software WebGL, no GPU) to screenshot and inspect your own output, and iterate on your own before finishing. Close any browser you open as soon as you've taken your screenshot.

Build an interactive Three.js scene of a single red Japanese maple (momiji) standing on a small rocky island in a still, misty lake. Its leaves are deep autumn red and orange; some drift down onto the water, where they float and leave gentle ripples. Low mist hangs over the lake and soft mountain silhouettes fade into the haze behind. A stone lantern stands beside the tree with a warm flame inside. Let the viewer interact: dragging across the water stirs the floating leaves and sends ripples through them, clicking the lantern makes it swing so its light sways across the water, and a dial turns the time of day from dawn through day and dusk to moonlight, changing the sky, the colour of the mist, the lighting and the reflections, with the moon and its reflection at night. Keep the mood calm and painterly, with a light wind moving the branches. Everything is built in code from Three.js geometry, shaders and materials; no external models or textures. Build it as index.html (plus any local asset files you create) in the current directory. Three.js may load from a pinned CDN. You may serve it locally and open it in headless chromium (/usr/bin/chromium, software WebGL, no GPU) to screenshot and inspect your own output, and iterate on your own before finishing. Close any browser you open as soon as you've taken your screenshot.

Build an explorable tropical island in Three.js. The island has white sand beaches, palm trees, a green hilly interior and a small fishing village of wooden huts with thatched roofs, joined to the sea by a long wooden pier with boats moored alongside. The ocean around it is animated, with waves, foam along the shore and clear shallow water over a reef where fish swim among corals and sea plants, fading to deep blue further out. Let the player switch between modes: walk on the island, swim at the surface, dive underwater (with underwater fog and caustic light), sail a small boat around the island, and fly a free camera. Add a time-of-day panel with a slider that moves the sun from morning through sunset to night, changing the sky, lighting and water colours, with stars and lit windows in the village at night. Show the controls on screen. Everything is built in code from Three.js geometry, shaders and materials; no external models or textures. Build it as index.html (plus any local asset files you create) in the current directory. Three.js may load from a pinned CDN. You may serve it locally and open it in headless chromium (/usr/bin/chromium, software WebGL, no GPU) to screenshot and inspect your own output, and iterate on your own before finishing. Close any browser you open as soon as you've taken your screenshot.

Build a conceptual X-16 engine in 3D with Three.js: four cylinder banks, one crankshaft and exposed mechanics inspired by experimental multi-bank engine architectures. Make it animate (pistons, rods and crank moving in sync) with orbit controls. Everything is built in code from Three.js geometry, shaders and materials; no external models or textures. Build it as a single self-contained index.html in the current directory. Three.js may load from a CDN or be vendored. You may serve it locally and open it in headless chromium (/usr/bin/chromium, software WebGL, no GPU) to screenshot and inspect your own output, and iterate on your own before finishing. Close any browser you open as soon as you've taken your screenshot.