// NESTED ZOOM — the frame recurses into itself: each level is a smaller,
// rotated copy inset inside the one before it, LEVELS deep.
{
    name: "Nested Zoom"
    engine: "screen"
    input0: "test"

    p0: 0.5  p1: 0.5  p2: 0.5
    dials: [
        {name: "ZOOM", bind: "p0", default: 0.5},
        {name: "LEVELS", bind: "p1", default: 0.5},
        {name: "SPIN", 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 z = 1.3 + 1.0 * self.user.x
            let levels = floor(mix(2.0, 5.0, self.user.y) + 0.5)
            let ang = 0.12 * (0.2 + 1.6 * self.user.z)
            let cs = cos(ang)
            let sn = sin(ang)
            let mut p = uv - vec2(0.5, 0.5)
            let mut i = 0.0
            loop {
                if i > levels - 0.5 {
                    break
                }
                p = vec2(p.x * cs - p.y * sn, p.x * sn + p.y * cs) * z
                p = vec2(fract(p.x + 0.5) - 0.5, fract(p.y + 0.5) - 0.5)
                i = i + 1.0
            }
            let w = p + vec2(0.5, 0.5)
            let tex = self.tex0.sample_as_bgra(clamp(w, vec2(0.0, 0.0), vec2(1.0, 1.0)))
            return vec4(tex.xyz, 1.0)
        }
    }
}