// DISC — the whole frame is unrolled onto a polar annulus: angle reads
// across the source horizontally, radius reads down it, a spinning donut.
{
    name: "Disc"
    engine: "screen"
    input0: "test"

    p0: 0.5  p1: 0.5  p2: 0.5
    dials: [
        {name: "SPIN", bind: "p0", default: 0.5},
        {name: "THICK", bind: "p1", default: 0.5},
        {name: "ZOOM", bind: "p2", default: 0.5}
    ]

    stages: [
        {kind: "bloom", threshold: 0.6, strength: 1.05, levels: 2}
    ]

    shader: draw.DrawVjFxScreen {
        fx_color: fn(uv: vec2, content: vec4, cmix: float) -> vec4 {
            let center = vec2(0.5, 0.5)
            let d = uv - center
            let r = length(d)
            let ang = atan2(d.y, d.x)
            let inner = 0.05 + 0.25 * self.user.y
            let outer = 0.5
            let rn = clamp((r - inner) / (outer - inner), 0.0, 1.0)
            let spin = modf(self.time_beat.y * 0.015 * (0.2 + 1.6 * self.user.x), 1.0)
            let an = fract((ang + 3.14159265) / 6.2831853 + spin)
            let zoom = 0.5 + 1.5 * self.user.z
            let w = vec2(an, clamp(rn * zoom, 0.0, 1.0))
            let tex = self.tex0.sample_as_bgra(w)
            return vec4(tex.xyz, 1.0)
        }
    }
}