// LISSAJOUS SCOPE — flying through an oscilloscope figure: the tunnel's
// centerline is a 3:2 Lissajous curve, phosphor-green on black, thin
// bands. Pattern taught: `path: "lissajous"` + knot_p/q as frequencies.
{
    name: "Lissajous Scope"
    engine: "tunnel"
    path: "lissajous"

    knot_p: 3.0
    knot_q: 2.0
    major: 6.5
    tube: 1.1
    rings: 900
    sides: 18
    fly: 3.6
    bands: 160.0

    beat_pulse: "0.6 * (0.2 + 1.6*p0)"
    // PERFORMANCE DIALS — mid-knob = the stock look, exact.
    p0: 0.5  p1: 0.5  p2: 0.5
    dials: [
        {name: "PUMP", bind: "p0", default: 0.5},
        {name: "GLOW", bind: "p1", default: 0.5},
        {name: "FLARE", bind: "p2", default: 0.5}
    ]

    color_bg: #x020604
    color_a: #x33ff88
    color_b: #x11aa55
    color_c: #xbbffcc

    fog: 0.09
    glow: "1.3 * (0.25 + 1.5*p1)"

    stages: [
        {kind: "bloom", threshold: "clamp(0.35 - (p2-0.5)*0.5, 0.02, 0.95)", strength: 1.6, 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 = along the bore 0..1, attr = (around, along, ring hash,
    // radius), content = the wall texel at this vertex, cmix = the
    // pre-gated content strength (0 without real channel video). The
    // wall DRAPE has its own pixel hook, `fx_wall` — this tunnel keeps
    // the stock one.
    // 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.DrawVjFxTunnel {
        fx_color: fn(t: float, attr: vec4, normal: vec3, wpos: vec3,
                     content: vec4, cmix: float) -> vec4 {
            return self.col_a.mix(self.col_b, t)
        }
    }
}