bool _lightning_los(const coord_def& source, const coord_def& target)
{
    // XXX: currently bounded by circular LOS radius;
    // XXX: adapt opacity -- allow passing clouds.
    return (exists_ray(source, target, opc_solid, bds_maxlos));
}

            if (!check_line_of_sight(source, monster->pos()))

            if (_lightning_los(source, monster->pos()))

                && check_line_of_sight(source, you.pos()))

                && _lightning_los(source, you.pos()))

static bounds_radius_sq bds_maxlos(LOS_RADIUS);

bool check_line_of_sight( const coord_def& source, const coord_def& target );

/**
 * Checks whether target is in sight of source.
 *
 * Only used from cast_chain_lightning currently.
 * XXX: Move to los.cc; integrate with other LOS code.
 */
bool check_line_of_sight(const coord_def& source, const coord_def& target)
{
    const int dist = grid_distance(source, target);

    // Can always see one square away.
    if (dist <= 1)
        return (true);
    // Currently we limit the range to 8.
    if (dist > MONSTER_LOS_RANGE)
        return (false);
    // Note that we are guaranteed to be within the player LOS range,
    // so fallback is unnecessary.
    return exists_ray(source, target);
}