// ATTRACTOR STORM — the second stateful-particle program: particles spawn
// on a SHELL and fall into an orbiting attractor with a strong tangential
// swirl — a storm eye that wanders. Every kick blasts the accretion disc
// outward (impulse) and the disc collapses back because velocity is REAL
// STATE integrated frame over frame. Speed paints color (speed_color).
{
    name: "Attractor Storm"
    engine: "simswarm"
    seed: 9

    count: 20164
    size: 0.06
    stretch: 0.06
    speed_color: 0.16
    spawn: "shell"

    curl: 0.5
    attract: 2.6
    swirl: 1.9
    gravity: 0.0
    impulse: "(1.2 + pulse * 3.2) * (0.2 + 1.6*p0)"
    drag: 0.55
    max_speed: 11.0
    life: 30.0
    bound: 6.5

    beat_pulse: 0.4

    // PERFORMANCE DIALS — mid-knob = the stock look, exact.
    p0: 0.5  p1: 0.5  p2: 0.5
    dials: [
        {name: "KICK", bind: "p0", default: 0.5},
        {name: "TRAIL", bind: "p1", default: 0.5},
        {name: "GLOW", bind: "p2", default: 0.5}
    ]

    color_bg: #x0c0508
    color_a: #x8f2a2a
    color_b: #xffb35a
    color_c: #xfff2e0

    cam_orbit: 0.10
    cam_height: 2.2
    glow: 1.3

    stages: [
        {kind: "feedback", amount: "min(0.6 + (p1-0.5)*0.7, 0.97)", zoom: 1.008, rotate: 0.003, dim: 0.93},
        {kind: "bloom", threshold: 0.45, strength: "1.4 * (0.25 + 1.5*p2)", 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 = age 0..1, attr = (id, speed, rnd, state age).
    // 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.DrawVjFxSimSwarmDraw {
        fx_color: fn(t: float, attr: vec4, normal: vec3, wpos: vec3) -> vec4 {
            let sp = clamp(attr.y * self.flow.y, 0.0, 1.0)
            let base = self.col_a.mix(self.col_b, sp)
            let hot = base.xyz + self.col_c.xyz * pow(sp, 3.0) * 0.6
            let fade = smoothstep(0.0, 0.06, t) * (1.0 - smoothstep(0.75, 1.0, t))
            let boost = 0.8 + self.time_beat.w * 0.9
            return vec4(hot * boost, fade)
        }

        fx_sprite: fn(uv: vec2, tint: vec4) -> vec4 {
            let d = length(uv - vec2(0.5, 0.5)) * 2.0
            let core = 1.0 - smoothstep(0.0, 0.45, d)
            let halo = 1.0 - smoothstep(0.12, 1.0, d)
            let a = clamp(core + halo * 0.55, 0.0, 1.0) * tint.w
            return vec4(tint.x * a, tint.y * a, tint.z * a, 0.0)
        }
    }
}