+ void set_offset(const Vector &offset_)
+ { this->offset = offset_; }
+
+ /* Returns the position of the upper-left corner of
+ * tile (x, y) in the sector. */
+ Vector get_tile_position(int x, int y) const
+ { return offset + Vector(x,y) * 32; }
+
+ Rectf get_bbox() const
+ { return Rectf(get_tile_position(0, 0), get_tile_position(width, height)); }
+
+ Rectf get_tile_bbox(int x, int y) const
+ { return Rectf(get_tile_position(x, y), get_tile_position(x+1, y+1)); }
+
+ /* Returns the half-open rectangle of (x, y) tile indices
+ * that overlap the given rectangle in the sector. */
+ Rect get_tiles_overlapping(const Rectf &rect) const;