WebGL Experience Skill

Produce a single self-contained index.html that renders a real-time WebGL (or WebGL2) visual full-screen, with a clean typographic overlay on top.

Why this is a powered artifact

OpenDesign detects getContext('webgl2') / new Worker / SharedArrayBuffer and renders this file in powered preview — a cross-origin-isolated iframe with allow-same-origin. That means real Web Workers, SharedArrayBuffer, WASM, and the full GPU pipeline are available. You do not need to work around the opaque sandbox. Prefer webgl2 for modern features; fall back to webgl when the effect allows.

Resource map

webgl-experience/
├── SKILL.md      ← you're reading this
└── example.html  ← a working WebGL2 aurora-field reference (READ FIRST)

Workflow

Step 0 — Read the reference

Read example.html end to end. Note the shape: one full-viewport <canvas>, a fragment-shader draw loop on a fullscreen triangle, a DPR-aware resize, and a requestAnimationFrame tick. The overlay (kicker → h1 → sub) is pure HTML/CSS layered above the canvas via z-index.

Step 1 — Choose the visual

Pick ONE technique that fits the brief:

• Fragment-shader field (default): domain-warped fbm noise, flow fields, plasma, gradients. Cheapest, always 60fps.
• Raymarched scene: SDF spheres/boxes with soft shadows for a 3D hero.
• Instanced geometry: thousands of points/quads driven by a vertex shader.
• Post-processed image: sample a data-URI texture and distort/dither it.

Step 2 — Build index.html

• Keep it one file, zero external requests (inline the shader source; embed any texture as a data: URI). Powered mode allows CDN loads, but self-contained previews are faster and portable.
• Always: alpha:false, DPR clamped to 2, viewport on resize, and a guard that shows a graceful message if the context is null.
• Compile shaders with error logging (getShaderInfoLog) so a typo fails loudly, not silently black.

Step 3 — Overlay + brand

• Map the two :root-level accent colors to the active DESIGN.md when one is present; otherwise use a restrained dark palette with a single vivid accent (the reference uses lime #63fe13).
• Headline ≤ 14ch, one supporting line. Never cover the whole canvas — the visual is the hero.

Step 4 — Self-review (P0)

• [ ] Renders continuously at ~60fps; the FPS badge updates.
• [ ] No WebGL console errors; getError() clean after first frame.
• [ ] Resizes crisply on window resize (no stretching / blur).
• [ ] Readable overlay contrast over the brightest frame.
• [ ] Degrades to a message (not a blank page) if webgl2 is unavailable.