// RTMultiShadow miss (runs in SHADE). Shadow miss → that light is visible
// from the surface, so add its pending contribution; up to LIGHT_COUNT of
// these resolve for the same pixel in one pass (atomic rtAccumulate, #30).
// Primary miss → near-black night sky so the colored lighting carries the
// frame.
fn miss_main(ray: RayDesc, payload: ptr<function, Payload>) {
    if ((*payload).shadowRay == 1u) {
        rtAccumulate((*payload).color);
        return;
    }
    let t = clamp(ray.direction.y * 0.5 + 0.5, 0.0, 1.0);
    rtAccumulate(mix(vec3<f32>(0.010, 0.012, 0.022),
                     vec3<f32>(0.030, 0.040, 0.075), t));
}