// CHECKER TILES — a plain square grid where alternating cells flip on
// opposite phases: half the checkerboard pops early in the sweep, the
// other half late, so the frame reads as a checkerboard mid-transition.
{
    name: "Checker Tiles"
    engine: "transition"
    p1: 0.5
    dials: [
        {name: "SOFT", bind: "p0", default: 0.2},
        {name: "CELLS", bind: "p1", default: 0.5},
        {name: "DIP", bind: "p2", default: 0.0}
    ]
    shader: draw.DrawVjFxDuo {
        trans: fn(uv: vec2, t: float) -> vec4 {
            let n = 5.0 + floor(self.user.y * 9.0)
            let cx = floor(uv.x * n)
            let cy = floor(uv.y * n)
            let parity = modf(cx + cy, 2.0)
            let field = 0.15 + parity * 0.55
            let soft = 0.02 + self.user.x * 0.25
            let tt = t * (1.0 + 2.0 * soft) - soft
            let m = smoothstep(tt - soft, tt + soft, field)
            let c = self.deck_b(uv).mix(self.deck_a(uv), m)
            let dim = 1.0 - 4.0 * clamp(t, 0.0, 1.0) * (1.0 - clamp(t, 0.0, 1.0)) * self.user.z * 0.9
            return vec4(c.xyz * dim, 1.0)
        }
    }
}