Procedural Fields
Do not start by stacking noise. Start by defining the fields the object physically or stylistically needs.
Field contract
Before shader code, write a field bundle:
coordinates
→ macro form
→ meso structure
→ derived causes
→ material channels
Example:
sphereDirection
→ warpedDirection
→ elevation + ridges + craterDepth
→ slope + cavity + latitude + moisture
→ biome + color + roughness + bump
Required workflow
- Choose coordinates that remain stable under camera and object motion.
- Lock real or perceptual scale for each frequency band.
- Create named primary fields. Never hide the whole look in one expression.
- Derive secondary fields from causes: slope from normals, shore from sea-level distance, wear from exposure, dirt from cavity.
- Reuse the same fields across color, roughness, normal, displacement, emission, and scattering.
- Add debug output for every named field.
- Filter high-frequency fields by derivatives, tessellation density, or camera distance.
Read references/field-stack-recipes.md
before implementation. It records sphere, terrain, water, and
structured-placement field contracts plus common parity defects.
Read the
procedural planet surface
for a shared CPU/GLSL field bundle whose height, continents, climate, biomes,
roughness, and normals remain independently inspectable.
Non-negotiable rules
- Independent noise per channel produces visual soup. Share structure.
- Domain warp the coordinates, not every result.
- Warp spherical coordinates tangentially, then renormalize.
- Use different frequency bands for silhouette, regions, surface breakup, and micro-normal.
- Do not displace geometry with frequencies the mesh cannot represent.
- Keep categorical masks broad enough to avoid isolated “bubble” regions.
- Parameter names must describe perception:
ridgeWidth, coastBlend, cavityDarkening, not noise3Amount.
Routing boundary
Use this skill when the shared field model is the task. Use
$threejs-procedural-materials when the task is channel assembly and material
response, and $threejs-procedural-planets when the deliverable is a complete
planetary body.
1---2name: threejs-procedural-fields3description: Build coherent procedural scalar and vector fields for Three.js materials and geometry. Use for terrain, planets, wear, biomes, clouds, water masks, displacement, roughness, normals, domain warping, and any visual where several channels must derive from shared causes.4---5
6# Procedural Fields
7
8Do not start by stacking noise. Start by defining the fields the object physically or stylistically needs.
9
10## Field contract
11
12Before shader code, write a field bundle:
13
14```text
15coordinates
16 → macro form
17 → meso structure
18 → derived causes
19 → material channels
20```
21
22Example:
23
24```text
25sphereDirection
26 → warpedDirection
27 → elevation + ridges + craterDepth
28 → slope + cavity + latitude + moisture
29 → biome + color + roughness + bump
30```
31
32## Required workflow
33
341. Choose coordinates that remain stable under camera and object motion.
352. Lock real or perceptual scale for each frequency band.
363. Create named primary fields. Never hide the whole look in one expression.
374. Derive secondary fields from causes: slope from normals, shore from sea-level distance, wear from exposure, dirt from cavity.
385. Reuse the same fields across color, roughness, normal, displacement, emission, and scattering.
396. Add debug output for every named field.
407. Filter high-frequency fields by derivatives, tessellation density, or camera distance.
41
42Read [references/field-stack-recipes.md](references/field-stack-recipes.md)
43before implementation. It records sphere, terrain, water, and
44structured-placement field contracts plus common parity defects.
45
46Read the
47[procedural planet surface](../threejs-procedural-planets/examples/procedural-planet-surface/planet-system.js)
48for a shared CPU/GLSL field bundle whose height, continents, climate, biomes,
49roughness, and normals remain independently inspectable.
50
51## Non-negotiable rules
52
53- Independent noise per channel produces visual soup. Share structure.
54- Domain warp the coordinates, not every result.
55- Warp spherical coordinates tangentially, then renormalize.
56- Use different frequency bands for silhouette, regions, surface breakup, and micro-normal.
57- Do not displace geometry with frequencies the mesh cannot represent.
58- Keep categorical masks broad enough to avoid isolated “bubble” regions.
59- Parameter names must describe perception: `ridgeWidth`, `coastBlend`, `cavityDarkening`, not `noise3Amount`.
60
61## Routing boundary
62
63Use this skill when the shared field model is the task. Use
64`$threejs-procedural-materials` when the task is channel assembly and material
65response, and `$threejs-procedural-planets` when the deliverable is a complete
66planetary body.
gabrielmoreira