// DUSK MURMURATION — three hundred starlings against a violet evening sky.
// Pattern taught here: the flock engine's GOAL POINT jumps every two beats,
// so the cloud of birds banks and swings IN TIME without a single binding;
// wing flap runs per bird in the vertex shader off baked phase hashes.
// Silhouette mode (additive: 0) fogs the far birds into the sky — depth
// for free.
{
    name: "Dusk Murmuration"
    engine: "flock"
    seed: 44

    birds: 340
    size: 0.16
    flight_speed: 2.5
    flap: 2.6
    bound: 7.0
    spacing: 0.58
    vision: 1.9
    goal_beats: 2
    predator: 0.0
    additive: 0.0
    bank: 1.3

    beat_pulse: "0.3 * (0.2 + 1.6*p0)"
    cam_orbit: 0.05
    fog: "0.055 * (0.2 + 1.6*p2)"
    glow: "0.25 + 1.5*p1"

    // 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: "HAZE", bind: "p2", default: 0.5}
    ]

    // Dark birds on a GLOWING dusk sky — the contrast IS the picture.
    color_bg: #x33204f
    color_a: #x150e24
    color_b: #x3a2547
    color_c: #xffb489

    stages: [
        {kind: "bloom", threshold: 0.8, strength: 0.7, 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 = speed 0..1, attr = (bird, speed01, hue, flap amplitude).
    // 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.DrawVjFxFlock {
        fx_color: fn(t: float, attr: vec4, normal: vec3, wpos: vec3) -> vec4 {
            let base = self.col_a.mix(self.col_b, attr.z)
            let gain = 0.5 + 0.6 * t + self.time_beat.w * 0.35
            return vec4(base.xyz * gain, 1.0)
        }
    }
}