Threejs Procedural Vegetation Agent Skill

Procedural Vegetation

Represent a plant as a growth hierarchy plus rendering adaptations. Do not model it as randomly scattered cylinders.

Build sequence

• Define a per-level species table: length, radius, taper, child count, emergence range, angle, twist, gnarliness, sections, radial segments.
• Grow branches iteratively from a queue so recursion depth and budgets remain inspectable.
• Emit each branch as oriented rings with an intentional UV seam.
• Update section orientation from:
• inherited direction;
• stochastic curvature;
• tropism or external force;
• optional attraction constraints.
• Spawn children with stratified longitudinal slots and independently permuted angular slots.
• Generate leaves only after branch topology is stable.
• Build foliage normals from both card orientation and local crown volume.
• Choose wind scope explicitly. Leaf-root deformation, branch hierarchy deformation, and whole-tree sway are separate systems.

Read references/structured-ash-growth-system.md and preserve its preset, continuation, child-placement, leaf, material, wind, and composition contracts before tuning.

Read the Ash Growth System implementation

with its authored preset for a

contract-accurate implementation and its diagnostic attributes.

Read the

stylized meadow grass implementation

for authored blade-cluster geometry with a procedural fallback, image-driven

path masking, per-instance origin/facing attributes, circular-arc rooted wind,

gust fronts, tip flutter, color clumps, macro variation, translucency, and rim

diagnostics.

Read the

GPU-computed grass implementation

for MRT blade-parameter generation, deterministic terrain-conforming placement,

Voronoi clumps, Bezier blade folding, wind-facing yaw, distance LOD/culling,

normal/color fading, translucency, and field diagnostics.

Read the

procedural surface ivy entry

and its complete

TypeScript implementation

for seeded spline-following stems, repeated mesh reprojection, tangent-plane

creep and droop, parallel-transport tube rings, growth reveal, instanced leaves

and umbels, and rigid petiole-hinge wind. Treat the TypeScript modules as the

only implementation; the entry file only re-exports them.

Visual failure conditions

• branches form visible helices;
• dense grass ignores terrain height or clump-level variation;
• every child emerges at the same relative height;
• bark texture scale changes with branch radius;
• leaves reveal flat card normals under rotation;
• leaf wind moves card roots instead of remaining anchored;
• branch wind is claimed to match a reference whose branches are static;
• different seeds change species identity rather than controlled variation;
• geometry cost grows without a per-level budget;
• surface-following stems are offset from the host or flip normals across seams;
• ivy branches ignore the tangent plane while attached;
• leaf wind rotates around the card center instead of the petiole.

Routing boundary

Use $threejs-procedural-geometry for generic branch-ring emission without a

growth model. This skill owns species tables, vine and branch topology,

surface-following growth, foliage, grass fields, roots, and rooted wind.