// KICK FORGE — a drumhead piled with steel shards: every kick fires an
// impulse that launches the pile ballistically; shards tumble, glint and
// rain back before the next hit, and the membrane rings a damped radial
// wave from the same impulse. Pattern taught: THE forge binding is `p0`
// (impulse gain) — bass slams real metal once audio is wired, while the
// `pulse` term keeps it forging on the free-running clock. Physics is
// stateless: position is a pure function of (phase, bpm, seeds), and a
// fading gain pulls its own shards back down.
{
    name: "Kick Forge"
    engine: "forge"
    seed: 11

    shards: 2200
    radius: 4.2
    impulse: 9.0
    gravity: 46.0        // high gravity = HIGH jumps (launches land per beat)
    spin: 1.2
    membrane_wave: 0.5
    shard_size: 0.17
    scatter: 0.55
    falloff: 0.55
    pile: 0.6
    glint: 1.2

    beat_pulse: 0.6
    p0: "0.6 + 2.6*bass"               // impulse gain — the kick moves the metal
    p1: "0.35 + 1.3*bass"              // membrane wave rides the lows
    p2: "0.25 + 1.5*high"              // hats fire the glints

    // PERFORMANCE DIALS — the engine's own p-levers; touching one holds
    // its audio binding above at a fixed gain.
    dials: [
        {name: "HEAT", bind: "p0", default: 0.5},
        {name: "RING", bind: "p1", default: 0.5},
        {name: "EMBER", bind: "p2", default: 0.5}
    ]

    color_bg: #x070608
    color_a: #x8a93a6      // cold steel
    color_b: #xff7a2a      // forge ember
    color_c: #xfff3d8      // white-hot glint

    cam_orbit: 0.10
    cam_fov: 52.0
    fog: 0.030
    glow: 1.3

    stages: [
        {kind: "bloom", threshold: 0.5, strength: "1.2 + 0.8*pulse", 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 = flight heat 0..1, attr = (id, aux, r0, r1).
    // 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.DrawVjFxForge {
        fx_color: fn(t: float, attr: vec4, normal: vec3, wpos: vec3) -> vec4 {
            let base = self.col_a.mix(self.col_b, fract(attr.w * 7.93))
            let flash = self.col_c * (t * 0.55)
            return vec4(base.xyz + flash.xyz, 1.0)
        }
    }
}