Share one toolbox: power functions, particles, shaders — and presets

[ewowi]

Effects used to hand-roll their own drawing, math and motion: each one carried its own line
walker, its own sine, its own fade, its own idea of how fast a frame is. This branch replaces
that with one shared toolbox, and migrates the existing effects onto it.

Two things fall out. Effects get shorter and more capable — anti-aliasing, sub-pixel
positioning and signed distance fields arrive everywhere at once rather than per effect. And
motion becomes a property of time rather than of hardware: the same settings look the same on
a 30 fps wall and a 5,000 fps desktop, with the faster device drawing it more smoothly.

What landed

Presets and a control surface. ControlModule saves and restores any part of the module
tree as a named JSON file. A Layers-only preset is hardware-portable; adding Drivers makes
it a device snapshot carrying pin maps. Presets publish to Home Assistant as a select.

The power-function library (docs/moonmodules/light/power-functions.md lists every
function with its callers):

• Drawing — Canvas, lines, bars, rects, circles, scroll, splat, anti-aliased lines
• Math — sin16/cos16, atan16, dist16, map32, easings, BeatPhase, hashInt
• Fields — value noise at 8 and 16 bits, fbm, turbulence, warp, blobs
• Signed distance fields — shapes, smin, and free anti-aliasing from coverage()
• Particles — an SoA pool over caller-owned buffers, forces, semi-implicit Euler, walls,
  collisions, emitters
• Shaders — the GLSL vocabulary in fixed point, plus raymarching where the SoC has an FPU

Twelve new effects (40 → 52), each a showcase for one part of the toolbox: SdfShapes,
PolarNoise, WaterRipple, Tunnel, Echo, Dissolve, Spectrum, Fireworks, Ballpit, Truchet,
Raymarch, VectorBalls.

Framerate independence as a system rule (architecture.md). Everything that changes over
time is driven by elapsed time, never by frame count. Quantising to a fixed 60 Hz and skipping
frames is explicitly the wrong fix, since it discards the smoothness the extra frames buy.
unit_Effects_framerate.cpp audits all 52 effects at 60 vs 1200 fps.

Bugs this found and fixed

Several were live before the branch, and none were visible from reading the code:

• sin16/cos16 returned unsigned where FastLED master and WLED main both return signed. A
  ported effect that writes sin16(x) + 32768 is offset by half scale with no error anywhere.
• isqrt64 returned 0 for UINT64_MAX — its first Newton step overflowed. Once collide()
  used it, that would have read as zero separation.
• lerp16 overflowed int32 on roughly a quarter of samples (undefined behaviour), and fbm16
  shifted each octave down by 8 before summing, making its output 8-bit in a 16-bit type: 195
  distinct values over 20,000 samples, now 15,118.
• Echo ran 1 feedback pass per second at 240 fps instead of 60 — the trail effectively froze.
• ParticlesEffect froze entirely at low speed on a fast device, where the per-frame step
  truncated to zero.

Performance

	main	branch
desktop tick (NoiseEffect, 4,096 lights)	129–142 µs	134–140 µs
esp32 tick	4,164 µs	4,164 µs
esp32s3-n16r8 flash	1,628 KB	1,699 KB

Desktop tick measured three runs each, side by side against a main worktree: the ranges
overlap and there is no regression. The repo-health "+13 µs ⚠" marker compares two single
samples of a noisy metric. Flash grows by the new effects and the library.

Raymarching measures 96 cycles/pixel on an S3 — below the 292 budgeted for a full 128×128
wall — which is why it is gated on SOC_CPU_HAS_FPU rather than restricted to desktop.

Known and deferred

• Fireworks still counts frames for its launch roll. It has two framerate bugs that
  currently cancel: frame-counted launches, and a fadeToBlackBy floor that erases the trail
  faster on a fast device. Fixing one exposes the other, and fixing both changes how the
  effect looks, so it gets its own commit.
• BouncingBalls has not moved onto the particle kernel; it wants ball-ball collisions,
  which is a rework rather than a migration.
• Worley noise and the remaining 16-bit noise tuning (gradient vs value noise, 3D
  fbm16, warp16/turbulence16) are backlogged, each to land with the first effect that
  needs it.

Review

CodeRabbit and two Reviewer passes. Findings fixed, except: the two grid guards in effects
(Layer::tick already gates on hasGrid, so a guard there is dead code and an orchestration
violation), map32's split numerator (needs both spans near 2^32; no call site does), and
moving FrameTime to core / abstracting raymarch behind a platform interface — both real,
both refactors across every caller rather than review fixes.

Summary by CodeRabbit

• New Features

  • Added a control surface for saving, applying, renaming, deleting, and ordering device presets.
  • Added physical-style encoders, faders, preset pads, visual feedback, drag-and-drop editing, and responsive layouts.
  • Added Home Assistant and WLED preset integration with live preset updates.
  • Added numerous lighting effects, including fireworks, particles, tunnels, ripples, spectrum visualization, and raymarching.
  • Added desktop port selection through command-line options.

• Bug Fixes

  • Improved rendering across grid sizes, channel counts, empty layouts, and varying frame rates.
  • Prevented invalid preset data and unsafe names from altering device state.