// MEADOW GALE — the LIVING WIND demo. `wind_field:` swaps the meadow's
// analytic sway for a 64x64 GPU wind SIM FIELD (sim.rs): a curl-noise base
// wind plus a gust channel that is INJECTED on the beat and ADVECTED
// DOWNWIND every frame. A gust is a traveling object — watch one bright
// band of bent, lit grass cross the field over a couple of seconds.
// Pattern taught here: wind_field + the field keys (flow/gust/travel/
// decay/scale/extent) read at document level.
{
    name: "Meadow Gale"
    engine: "grass"
    seed: 12

    blades: 11000
    area: 10.0
    height: 0.95
    clump: 0.5

    // The wind field. flow = base wind, gust = beat impulse energy,
    // travel = how fast a gust crosses the field (uv/sec), decay = how
    // long it survives, extent = the world half-extent the field spans.
    wind_field: "wind"
    flow: 1.1
    gust: "(2.4 + pulse * 1.6) * (0.2 + 1.6*p0)"
    travel: 0.30
    decay: 0.45
    scale: 2.6
    extent: 11.0

    sway: "0.85 * (0.25 + 1.5*p1)"
    beat_pulse: 0.2
    beat_rate: 0.5
    // PERFORMANCE DIALS — mid-knob = the stock look, exact.
    p0: 0.5  p1: 0.5  p2: 0.5
    dials: [
        {name: "GUST", bind: "p0", default: 0.5},
        {name: "WIND", bind: "p1", default: 0.5},
        {name: "GLOW", bind: "p2", default: 0.5}
    ]

    color_bg: #x101408
    color_a: #x4a6a14
    color_b: #xc8e05a
    color_c: #xfff8d0

    cam_orbit: 0.045
    cam_height: 3.4
    fog: 0.05
    glow: "1.1 * (0.25 + 1.5*p2)"

    stages: [
        {kind: "bloom", threshold: 0.6, strength: 1.05, 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 = arc along the blade 0..1, attr = (row, arc, hue, half width).
    // 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.DrawVjFxMeshField {
        fx_displace: fn(pos: vec3, normal: vec3, attr: vec4) -> vec3 {
            return vec3(0.0, 0.0, 0.0)
        }

        fx_color: fn(t: float, attr: vec4, normal: vec3, wpos: vec3) -> vec4 {
            let base = self.col_a.mix(self.col_b, clamp(attr.z, 0.0, 1.0))
            let tip = self.col_c * (clamp(t, 0.0, 1.0) * 0.35)
            let flash = self.col_c * (self.time_beat.w * 0.5)
            return vec4(base.xyz + tip.xyz + flash.xyz, 1.0)
        }
    }
}