Threejs Procedural Vfx Agent Skill

Procedural VFX

Build effects from an event envelope, motion field, geometry representation, and shading response. Avoid independent particle emitters that happen to share a color.

Effect graph

subject/event state
  → effect-specific geometry, voxel fields, or instance attributes
  → flow-facing masks or analytic age
  → material response
  → pool/lifetime ownership
  → HDR and bloom contribution

Read references/procedural-vfx-system.md

for ship-conforming reentry shells, capsule wakes, dense instanced

spark/debris pools, holographic projection shells, HDR hierarchy, and

implementation limits.

Read references/volumetric-fluid-fire.md

for three-dimensional texture ownership, fixed fluid-compute scheduling,

mesh-surface injection, pressure projection, moving SDF boundaries,

temperature-mapped HDR raymarching, exact presets, and failure diagnostics.

Read references/volumetric-aurora-curtains.md

for finite emissive-slab bounds, warped curtain density, uniform ray steps,

gentle start jitter, matching screen/probe materials, exact constants, limits,

and failure diagnostics.

Read the reentry plasma implementation

for closed layered wake shells, flow-axis deformation, advected filament

fields, opacity shaping, and additive emission diagnostics.

Read the

hologram projection material

for the additive rim shell itself: squared Fresnel incidence with grazing

falloff, footprint-filtered object-space scanlines, height-phased glitch

displacement, and index-gated participation. Read its

shape-transition driver

for the shared sweep range across a shape set, the linear progress ramp inside a

longer dwell, and the complementary-discard handover.

Read the

volumetric fluid fire implementation

for the complete WebGPU/TSL velocity, dye, pressure, vorticity, emitter,

collision, raymarch, and diagnostic system plus its calibrated fire preset.

Read the

raymarched aurora implementation

for the reusable emitting field, perspective-ray material, four-sample

equirectangular radiance material, shared uniforms, and calibrated curtain

preset without sky, terrain, weather, lighting, or renderer setup.

Rules

• Every layer must have a role in silhouette, motion, illumination, or residue.
• Give velocity, dye, pressure, vorticity, and collisions explicit texture

ownership and one fixed compute schedule.

• For low-angle aurora, use a finite shallow emitting footprint, uniform ray

steps, gentle start jitter, and step-length-weighted accumulation. Do not add

extinction or an elevation gate after the footprint already removes the long

limb path.

• Keep aurora emission separable from sky, stars, atmosphere, terrain lighting,

weather, and grading; expose the same radiance through perspective and

equirectangular materials.

• Convert velocity to volume UVW with the world-size vector; never advect a

non-cubic volume as though its axes had equal scale.

• Keep the pressure ping-pong endpoint consistent with the projection read.
• Use normalized lifetime curves instead of scattered time constants.
• Derive secondary motion from the same flow or event direction.
• Keep bloom as a response to HDR emission, not as the effect's only shape.
• Pool instances and trails; do not allocate per burst.
• Filter every periodic band by pixel footprint, and fade it to the band's own

mean rather than to zero.

• Measure rim incidence in a frame built from an inverse-transpose normal matrix.
• Give a multi-shape transition one shared normalised range and complementary

discards, never per-shape ranges or overlapping coverage.

• Expose spawn, simulation, overdraw, and luminance debug views.
• Include a non-bloom baseline that remains legible.

Routing boundary

Use $threejs-temporal-surfaces only for the screen-space

frost/touch-history pipeline. Use $threejs-precipitation-surfaces for

falling rain or snow, splash flipbooks, and weather events that alter ground

materials. Use $threejs-volumetric-clouds for atmospheric weather layers and

planet-scale cloud volumes. Use $threejs-atmosphere-aerial-perspective for

molecular/aerosol sky scattering and surface-segment aerial perspective. Keep

emissive aurora curtain volumes, bounded interactive fire and smoke,

subject-space plasma, generated wakes, sparks, pooled debris, and additive

projection shells in this skill.