// MIRROR ROTATE B — the same fold-across-an-axis mirror, but the axis
// SNAPS to a new angle every beat instead of spinning continuously — a
// stepped, stroboscopic cousin of Mirror Rotate A.
{
    name: "Mirror Rotate B"
    engine: "screen"
    input0: "test"

    p0: 0.5  p1: 0.5  p2: 0.5
    dials: [
        {name: "STEPS", bind: "p0", default: 0.5},
        {name: "SHIFT", bind: "p1", default: 0.5},
        {name: "EDGE", 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 pi = 3.14159265
            let steps = mix(3.0, 12.0, self.user.x)
            let beat_id = floor(self.time_beat.y)
            let slot = modf(beat_id, steps)
            let ang = (slot / steps) * pi
            let cs = cos(ang)
            let sn = sin(ang)
            let u = vec2(cs, sn)
            let n = vec2(-sn, cs)
            let shift = (self.user.y - 0.5) * 0.5
            let c = uv - vec2(0.5, 0.5)
            let along = c.x * u.x + c.y * u.y
            let perp = c.x * n.x + c.y * n.y - shift
            let fperp = abs(perp) + shift
            let p = u * along + n * fperp
            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)))
            let seam = smoothstep(0.0, 0.01 + 0.05 * self.user.z, abs(perp))
            let out = tex.xyz * (0.6 + 0.4 * seam) + vec3(1.0, 1.0, 1.0) * (1.0 - seam) * 0.2
            return vec4(out, 1.0)
        }
    }
}