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.

This skill contains exemplary examples and assets beyond descriptive guidance, they're worth studying, referencing, or even copying. Use them sufficiently when relevant and do NOT blindly skip them.

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 references/filmic-lens-flare.md for HDR emitter extraction, optical-axis invariants, field-angle pupil deformation, finite ghost families, spectral rings, localized bloom, film response, 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.

Read the filmic lens-flare implementation for top-origin HDR sun detection, panorama-ray reconstruction, stable source projection, finite radial ghost families, field-deformed pupil shapes, spectral ring and star response, localized bloom, and the complete filmic composite.

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.
• Derive lens ghosts from an HDR emitter, keep every synthetic centre on one optical axis, and deform pupil footprints from object-space field angle rather than screen radius.
• Keep the lens-flare family finite; do not extend calibrated terminal haze into an arbitrary bead chain or place diffraction stars at ghost centres.
• 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 standalone filmic HDR lens-flare compositors, emissive aurora curtain volumes, bounded interactive fire and smoke, subject-space plasma, generated wakes, sparks, pooled debris, and additive projection shells in this skill. Keep lens flare in $threejs-atmosphere-aerial-perspective when it remains one stage in a shared sky-scattering and aerial-perspective composition.