Tidepool v2 — a WebGPU compute study

262,144 particles + 1,024 fish + bioluminescence, all simulated on the GPU with three.js r185 WebGPURenderer + TSL compute. Zero CPU physics.

Systems

• Tide particles — curl-noise currents, 4 modes (Drift/Kelp/School/Pulse)
• Bioluminescence — per-particle excitement buffer; stirring, bursts, and turbulence make the water glow, then it fades back to dark
• Fish school — 2nd compute system; instanced darts oriented along velocity with speed-paced tail wiggle; they school, flee your cursor, scatter on Pulse
• Caustic sand floor — procedural ridged-noise caustics
• Post — RenderPipeline bloom + vignette (flat screens only)
• WebXR — stand inside the pool; WebGL fallback for browsers without WebXR+WebGPU (setupWebGLXRFallback)

Gotchas applied (from the Unbuilt Theater / easteregg session)

• Billboard quads, never gl_Points (no ~64px Apple GPU size cap)
• All animation dt-based (90 Hz headset safe)
• Angular size clamp min(size, camDist*0.14) — fill-rate/white-out guard when standing inside the cloud
• No bloom in XR + uBoost compensation; left-pinch brightness ladder (×0.5/0.75/1/1.5/2.25); right pinch cycles modes
• Meters-scale via uWorldScale uniform (0.09 → ~4.7 m pool), not group scale
• requiredLimits: { maxStorageBuffersInVertexStage: 3 } — 3 storage buffers read in the vertex stage exceeds some default device limits

URL params

?n=65536|262144|524288 · ?xrscale=0.09 · ?xrboost=1.5

Deploy

Static, no build step. Hosted on GitHub Pages from this repo (main branch, root). Live at https://agilelens.github.io/tidepool/ To point a subdomain at it later: CNAME tidepool.agilelens.com -> agilelens.github.io and set the custom domain in repo Settings > Pages.