| name | threejs-procedural-geometry |
| description | Build production procedural mesh systems in Three.js. Use for complete hard-surface object assemblies, tilted shell lofts, UV-owned apertures, sculpted rail and frame profiles, oriented branch rings, semantic mesh writers, deliberate skins and caps, fin lofts, custom normals, material slots, instancing decisions, and close-inspection geometry budgets. |
Procedural Geometry
Generate geometry from a semantic plan and an explicit coordinate frame. Triangle emission is the final compilation step, not the design model.
Build order
- Define dimensions and semantic segments.
- Generate a centerline, boundary, profile, or placement plan.
- Build the mechanism-appropriate local parameterization or branch orientation.
- Emit vertices with intentional seams and material ownership.
- Generate UVs from real distance.
- Validate winding, normals, tangents, bounds, and degenerates.
- Select merging, instancing, or LOD by update and material behavior.
Read references/profile-sweeps-and-mesh-writers.md
for the exact sculpted-frame profile, rail emission, tree rings, semantic mesh
writer, and their observed scaling limits.
Read the
sculpted gallery frame geometry
for the profile sweep, miter-like rail mapping, authored PBR surface
bundles, grazing spotlights, selective bloom ownership, and geometry
diagnostics.
Read
references/complete-submarine-assembly.md
for the exact dimensioned object contract, shared loft/sweep kernel, UV-owned
apertures, semantic subassemblies, generated fittings, and complete-model
diagnostics.
Read the
porcelain-and-brass submarine model
for a complete hard-surface assembly with a tilted-collar hull loft,
parallel-transport trim, furnished glass cabin, shrouded propeller, lens-section
fins, generated material inputs, and per-part triangle evidence.
Read the
procedural financial tower compiler
for semantic placement compilation and material-slot instancing at building
scale.
Failure conditions
- profile orientation flips along a curve;
- caps reuse side vertices and create averaged edge normals;
- UV scale changes with segment count;
- arbitrary vertex merging destroys hard edges or material boundaries;
- generated dimensions are hidden in magic multipliers;
- instancing is used despite per-instance topology differences;
- triangle count is the only reported complexity metric;
- apertures, frames, and glazing use unrelated coordinate systems;
- complete object parts are positioned by late visual nudges instead of a
shared dimension contract.
Routing boundary
This skill owns reusable mesh emission. Use
$threejs-procedural-materials when surface identity is primary,
$threejs-procedural-architecture for a building grammar, and
$threejs-procedural-vegetation for a growth hierarchy; those subject skills
may then apply these geometry mechanisms.
