#define LOS_DIAMETER (LOS_RADIUS * 2 + 1)

    // Preserve floor props around the player, primarily so that
    // blood-splatter doesn't appear out of nowhere when doing an
    // area shift.
    FixedArray<unsigned short, LOS_DIAMETER, LOS_DIAMETER> fprops;
    const coord_def los_delta(LOS_RADIUS, LOS_RADIUS);
    radius_iterator ri(you.pos(), LOS_RADIUS);
    for ( ; ri; ++ri )
        fprops(you.pos() - *ri + los_delta) = env.map(*ri).property;

    radius_iterator ri2(you.pos(), LOS_RADIUS);
    for ( ; ri2; ++ri2 )
        env.map(*ri2).property = fprops(you.pos() - *ri2 + los_delta);