// PILLAR SANCTUM — the raymarch engine's flagship: an infinite hypostyle
// hall of twisted columns, flown down one open lane. The ENTIRE scene is
// the scene_sdf subclass below: domain repetition puts a column in every
// cell, entasis bulge + a beat-pulsed twist shape it, floor and ceiling
// close the hall. Pattern taught: `scene_sdf` is the variant mechanism —
// override one function, inherit the whole marcher (march loop, normal,
// AO, soft shadow, cosine palette, fog).
{
    name: "Pillar Sanctum"
    engine: "raymarch"

    steps: 72
    max_dist: 44.0
    cam: "fly"
    cam_speed: 2.1
    cam_dist: 6.0        // fly mode: cam_dist * 0.17 = weave amplitude
    cam_height: 2.1
    cam_fov: 66.0
    shadow: 1

    beat_pulse: "0.45 * (0.2 + 1.6*p0)"
    beat_rate: 1.0
    fog: "0.055 * (0.2 + 1.6*p2)"
    glow: "1.05 * (0.25 + 1.5*p1)"

    // PERFORMANCE DIALS — mid-knob = the stock look, exact.
    p0: 0.5  p1: 0.5  p2: 0.5
    dials: [
        {name: "PUMP", bind: "p0", default: 0.5},
        {name: "GLOW", bind: "p1", default: 0.5},
        {name: "HAZE", bind: "p2", default: 0.5}
    ]

    color_bg: #x140a06
    color_a: #xffc890
    color_b: #x8a3c1a
    color_c: #xfff2dc

    stages: [
        {kind: "bloom", threshold: 0.55, strength: 1.15, levels: 3}
    ]

    shader: draw.DrawVjFxRaymarch {
        scene_sdf: fn(p: vec3) -> vec2 {
            // Columns on a 4.2 grid, offset half a cell so the fly lane
            // (x near 0) stays clear of stone.
            let cell = 4.2
            let q = vec2(
                self.rep1(p.x + cell * 0.5, cell),
                self.rep1(p.z + cell * 0.5, cell)
            )
            // Twist by height, pumped by the beat pulse.
            let tw = p.y * (0.45 + 0.30 * self.time_beat.w)
            let qq = self.rot2(q, tw)
            // Entasis: the classical bulge, breathing a little.
            let r = 0.40 + 0.09 * sin(p.y * 1.9 + 1.2) + 0.04 * self.time_beat.w
            let cq = abs(qq) - vec2(r, r)
            let col = length(max(cq, vec2(0.0, 0.0)))
                + min(max(cq.x, cq.y), 0.0) - 0.10
            let floor_d = p.y + 1.5
            let ceil_d = 6.6 - p.y
            // Twist is not an isometry: keep the estimate conservative.
            let d = min(col * 0.72, min(floor_d, ceil_d))
            // Material: column bands by height, floor/ceiling in their own
            // palette slot.
            let mut m = 0.82
            if col * 0.72 < min(floor_d, ceil_d) {
                m = fract(p.y * 0.16 + 0.1)
            }
            return vec2(d, m)
        }
    }
}