// CIRCLE MAGNIFIER — a round lens patrols an elliptical path over the
// frame, bulging its patch of content outward with a bright rim on its edge.
{
    name: "Circle Magnifier"
    engine: "screen"
    input0: "test"

    p0: 0.5  p1: 0.5  p2: 0.5
    dials: [
        {name: "SIZE", bind: "p0", default: 0.5},
        {name: "POWER", bind: "p1", default: 0.5},
        {name: "DRIFT", 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 speed = 0.15 + 0.6 * self.user.z
            let cx = 0.5 + 0.26 * cos(self.time_beat.x * speed)
            let cy = 0.5 + 0.2 * sin(self.time_beat.x * speed * 1.3)
            let center = vec2(cx, cy)
            let radius = 0.08 + 0.2 * self.user.x
            let d = uv - center
            let r = length(d)
            let inside = 1.0 - smoothstep(radius * 0.85, radius, r)
            let mag = 1.0 + 2.6 * self.user.y
            let rr = clamp(r / max(radius, 0.0001), 0.0, 1.0)
            let bulge = pow(rr, 1.0 / mag)
            let dir = d / max(r, 0.0001)
            let lensed = center + dir * bulge * radius
            let w = mix(uv, lensed, inside)
            let tex = self.tex0.sample_as_bgra(clamp(w, vec2(0.0, 0.0), vec2(1.0, 1.0)))
            let rim = smoothstep(radius * 0.88, radius, r) * (1.0 - smoothstep(radius, radius * 1.08, r))
            let out = tex.xyz + vec3(1.0, 1.0, 1.0) * rim * 0.25
            return vec4(out, 1.0)
        }
    }
}