// DOORS V — the reverse of Barn Doors V: deck B's two panels swing in
// from the top and bottom edges and shut over deck A at the horizontal
// centre seam. FLIP swaps which deck does the closing.
{
    name: "Doors V"
    engine: "transition"
    dials: [
        {name: "SOFT", bind: "p0", default: 0.1},
        {name: "FLIP", bind: "p1", default: 0.0},
        {name: "DIP", bind: "p2", default: 0.0}
    ]
    shader: draw.DrawVjFxDuo {
        trans: fn(uv: vec2, t: float) -> vec4 {
            let field = min(uv.y, 1.0 - uv.y) * 2.0
            let soft = 0.005 + self.user.x * 0.2
            let flip = step(0.5, self.user.y)
            let tt = mix(t, 1.0 - t, flip)
            let edge = tt * (1.0 + 2.0 * soft) - soft
            let inside = smoothstep(edge + soft, edge - soft, field)
            let cin = self.deck_b(uv).mix(self.deck_a(uv), flip)
            let cout = self.deck_a(uv).mix(self.deck_b(uv), flip)
            let c = cout.mix(cin, inside)
            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)
        }
    }
}