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name: webgl-raymarched-hero description: | A real-time raymarched 3D hero — soft-shadowed morphing metaballs with a fresnel rim light, sphere-traced per pixel in a fragment shader with a slow camera orbit. No meshes, no textures. Rendered as a single self-contained index.html. Use when the brief asks for a "raymarch", "signed distance field", "SDF", "3D hero", "metaballs", "blobs", or a shader-based 3D scene. OpenDesign serves this in powered-preview mode so the GPU stack actually runs. triggers:

• "raymarch"
• "raymarching"
• "sdf"
• "signed distance field"
• "metaballs"
• "3d hero"
• "blobs"
• "光线步进"
• "有向距离场" od: mode: prototype platform: web scenario: design preview: type: html entry: index.html reload: debounce-100 design_system: requires: false sections: [color, typography] craft: requires: [animation-discipline]

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Raymarched Hero Skill

Produce a single self-contained index.html that renders a real-time 3D scene entirely in a fragment shader via sphere tracing, full-screen, with a clean typographic overlay on top.

Why this is a powered artifact

OpenDesign detects getContext('webgl2') and renders this file in powered preview — a cross-origin-isolated iframe with allow-same-origin. The full GPU pipeline is available; you do not need to work around the opaque sandbox.

Resource map

webgl-raymarched-hero/
├── SKILL.md      ← you're reading this
└── example.html  ← a working SDF metaball raymarcher (READ FIRST)

Workflow

Step 0 — Read the reference

Read example.html end to end. Note the shape: one fullscreen triangle; a map(p) signed-distance function that smooth-unions (smin) several moving spheres; normals by finite differences; a softShadow march; and a camera built from ro/ta with a slow orbit. Shading = diffuse × soft shadow + fresnel rim + a tight specular.

Step 1 — Choose the SDF

Keep the marcher cheap so it holds 60fps:

• Metaballs (default): a few spheres blended with smin — organic, always readable.
• Rounded primitives: box/torus/capsule SDFs with domain repetition for a structured hero.
• Displaced surface: a sphere plus a low-amplitude noise displacement for a molten look.

Step 2 — Build index.html

• One file, zero external requests. Fullscreen triangle + fragment raymarch.
• Bound the march: cap iterations (~90), early-out on hit (d < 0.001) and on far distance; clamp DPR to ~1.5 — raymarching is per-pixel heavy.
• Light it: diffuse, a soft/penumbra shadow, a fresnel rim (pow(1 - dot(n,-rd), 3)), and one specular lobe. Gentle gamma at the end.
• Compile shaders with error logging so a typo fails loudly, not silently black.

Step 3 — Overlay + brand

• Map the accent colors to the active DESIGN.md when one is present; otherwise a restrained dark palette with one vivid accent (the reference tints the surface toward lime #63fe13 and rims it in teal).
• Headline ≤ 13ch plus one supporting line. Keep the 3D form as the hero.

Step 4 — Self-review (P0)

• Renders continuously at ~60fps; the FPS badge updates.
• Surface has real depth cues: shadow, rim, and a moving specular.
• No banding artifacts at the silhouette; normals are stable.
• Resizes crisply on window resize (no stretching / blur).
• Degrades to a message (not a blank page) if webgl2 is unavailable.