Function reflected_visible_set 

pub fn reflected_visible_set(
    bvh: &Bvh,
    reflected_frustum: &Frustum,
    eye: [f32; 3],
    always_draw: &[u32],
    out: &mut Vec<u32>,
)

Resolve the CPU visible set for a planar mirror render: BVH-cull the cullable draw objects against the reflected-camera frustum, then append the always-draw fallback (skybox, rooms) so it appears in the reflection too. Mirrors the main camera’s visible-set resolution but against the reflected frustum, so geometry visible only in the reflection (behind or beside the main camera, outside its frustum) is captured instead of reusing the main camera’s set. eye is the reflected camera position, consulted only for the leaves’ distance-based cull. out is cleared then refilled, so a caller can reuse one buffer across planes.