// LASER LOOM — three chorus strands of the harmonograph at hue offsets,
// drawn as additive laser light with feedback trails. Pattern taught: the
// strand channel (each strand offsets the pendulum phases slightly) turns
// one curve into a braid; `p0` scales DETUNE with the bar so the braid
// breathes apart and snaps back; width pumps on the pulse.
{
    name: "Laser Loom"
    engine: "harmonograph"
    seed: 68

    segments: 1400
    strands: 3
    freq_x: 3.0
    freq_y: 4.0            // 3:4 — the shell family
    freq_z: 2.0
    damping: 0.6
    detune: 0.10
    turns: 5.0
    width: 0.042
    morph_beats: 8

    grow: "loop"
    grow_beats: 8
    beat_pulse: 0.7
    p0: "0.5 + 0.5 * sin(bar * tau)"   // braid breathes over the bar
    p1: "0.5 * pulse"                  // width slams on the beat
    p3: "fract(beat * 0.02)"           // slow hue spin, wrapped 0..1

    // PERFORMANCE DIALS — the engine's own p-levers; touching DETUNE or
    // WIDTH overrides its music binding above with a held value.
    dials: [
        {name: "DETUNE", bind: "p0", default: 0.5},
        {name: "WIDTH", bind: "p1", default: 0.5},
        {name: "DEPTH", bind: "p2", default: 0.0}
    ]

    color_bg: #x030309
    color_a: #x40ffcc
    color_b: #xff40cc
    color_c: #xffffff

    cam_orbit: 0.10
    cam_dist: 6.0
    fog: 0.015
    glow: 1.0

    stages: [
        {kind: "feedback", amount: "0.42 + 0.15 * pulse", zoom: 1.006,
         rotate: 0.003, dim: 0.90},
        {kind: "bloom", threshold: 0.5, strength: 1.15, levels: 3}
    ]

    // THE LOOK LIVES HERE. This block is not a reference to the
    // engine's shader — it IS the pixel math this effect runs.
    // Rewrite it and the effect looks different; everything else
    // (geometry, motion, the content coupling, the beat) keeps
    // working, because the block SUBCLASSES the engine shader.
    // Inputs: t = curve position 0..1, attr = (strand, t, rnd, side).
    // Signals: self.time_beat (time, beat, phase, pulse),
    // self.sig (bar, bpm, energy, dt), self.user (p0..p3),
    // self.col_a/b/c/bg, self.fog (density, glow, content, -).
    shader: draw.DrawVjFxHarmono {
        fx_color: fn(t: float, attr: vec4, normal: vec3, wpos: vec3) -> vec4 {
            let strand01 = self.geom.geom_uv.y
            let hue = fract(t * 0.85 + strand01 * 0.34 + self.user.w)
            return self.col_a.mix(self.col_b, hue)
        }
    }
}