// PENDULUM CATHEDRAL — the camera stands INSIDE a huge, slowly morphing
// harmonograph figure with real z-depth. Pattern taught: `p2` adds depth
// to the third pendulum axis so the figure becomes architecture; grow is
// OFF (the figure stands complete) and the drama comes from the 32-beat
// figure morph + a width swell that follows the bar like an organ.
{
    name: "Pendulum Cathedral"
    engine: "harmonograph"
    seed: 12

    segments: 2400
    strands: 2
    freq_x: 2.0
    freq_y: 3.0
    freq_z: 2.0
    damping: 0.3
    detune: 0.07
    turns: 9.0
    width: 0.09
    morph_beats: 32        // the liturgy pace

    grow: "off"
    beat_pulse: 0.5
    p1: "0.5 * env(bar)"   // organ swell per bar
    p2: 1.4                // the cathedral depth

    // PERFORMANCE DIALS — the engine's own p-levers; DEPTH rests at the
    // knob's ceiling (the doc holds 1.4 until the knob is touched).
    dials: [
        {name: "DETUNE", bind: "p0", default: 0.0},
        {name: "WIDTH", bind: "p1", default: 0.5},
        {name: "DEPTH", bind: "p2", default: 1.0}
    ]

    color_bg: #x060410
    color_a: #x8060ff
    color_b: #x30a0c0
    color_c: #xfff8f0

    cam_orbit: 0.16
    cam_dist: 3.6
    cam_height: 0.4
    cam_fov: 70
    fog: 0.10
    glow: 1.2

    stages: [
        {kind: "bloom", threshold: 0.4, strength: 1.4, levels: 3},
        {kind: "feedback", amount: 0.4, zoom: 1.002, rotate: 0.0, dim: 0.93}
    ]

    // 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)
        }
    }
}