Function footprint_cell 

pub fn footprint_cell(
    cells: &Cells,
    terrain: &HeightGrid<'_>,
    rules: &PlacementRules,
    rect: Rect,
    degrees: i32,
    x: i32,
    y: i32,
    owner_ok: impl Fn(usize) -> bool,
) -> (bool, bool)

One cell of a footprint, as the placement test and the overlay test it: whether it admits the building (with the cell’s mask), and whether its footprint character is . (the cell is not changed, and its zone count is not checked).

Original: FUN_140106850; the cell test is FUN_1400a4aa0, the placement test FUN_1400a2a50.