| name | threejs-temporal-surfaces |
| description | Build view-aligned and screen-space surface effects in Three.js. Use for touch-history frost and thaw, ping-pong accumulation, reduced-resolution blur, crystalline masks, two-scale refraction, and procedural rain droplets that refract and blur a background through wet glass. |
Temporal Surfaces
Choose persistent history or procedural screen-space evolution explicitly. Do
not fake accumulation with time-only noise, and do not allocate history for an
effect whose complete state is analytic in time.
Pipeline
persistent surface: input -> ping-pong state -> blur -> structure -> refraction
procedural surface: time/coverage -> analytic field -> optical normal -> refraction/blur
Read references/ping-pong-accumulation.md
for an exact frost pass graph, pointer-history channels, blur and refraction
coupling, and implementation defects that must be corrected.
Read the
touch-history frost implementation for the
previous/deposit/next state transition, reduced blur, static structures,
frost-mask composition, and two-scale refraction.
Read references/refractive-window-rain.md
and the
refractive window rain implementation
for layered static and travelling droplets, finite-difference optical normals,
background refraction, stochastic disc blur, aspect fill, and presentation.
Rules
- Separate persistent state, analytic procedural state, and scene color.
- Preserve separate visible-mask and tilt-response channels.
- Use half-float for this history path unless a measured lower format is equivalent.
- Convert per-frame history decay to frame-rate-independent decay.
- Run the two-pass scene blur at reduced resolution.
- Pre-render static procedural textures once.
- Define and test resize/reset behavior for both history targets and static targets.
- Do not route world footprints, object-UV paint, or simulation-plane wetness here; this skill is view-aligned or screen-space.
Routing boundary
Use $threejs-procedural-vfx for world- or object-space residue and particles.
Use $threejs-precipitation-surfaces for world-space rain, puddles, snow, and
weather-surface coupling. This skill owns view-aligned wet-glass optics and
screen-space persistent history.
