1 files changed, 47 insertions, 0 deletions
diff --git a/crawl-ref/source/view.h b/crawl-ref/source/view.h
index b0e6e0c2c4..9994707b12 100644
--- a/crawl-ref/source/view.h
+++ b/crawl-ref/source/view.h
@@ -244,4 +244,51 @@ unsigned short dos_brand( unsigned short colour,
                           unsigned brand = CHATTR_REVERSE);
 #endif
 
+// This class can be used to fill the entire surroundings (los_range)
+// of a monster or other position with seen/unseen values, so as to be able
+// to compare several positions within this range.
+class monster_los
+{
+public:
+    monster_los();
+    virtual ~monster_los();
+
+    // public methods
+    void set_monster(monsters *mon);
+    void set_los_centre(int x, int y);
+    void fill_los_field(void);
+    bool in_sight(int x, int y);
+
+protected:
+    // protected methods
+    coord_def pos_to_index(coord_def &p);
+    coord_def index_to_pos(coord_def &i);
+
+    void set_los_value(int x, int y, bool blocked, bool override = false);
+    int get_los_value(int x, int y);
+    bool is_blocked(int x, int y);
+    bool is_unknown(int x, int y);
+
+    void check_los_beam(int dx, int dy);
+
+    // The (fixed) size of the array.
+    static const int LSIZE = 2 * LOS_RADIUS + 1;
+
+    static const int L_VISIBLE =  1;
+    static const int L_UNKNOWN =  0;
+    static const int L_BLOCKED = -1;
+
+    // The centre of our los field.
+    int gridx, gridy;
+
+    // Habitat checks etc. should be done for this monster.
+    // Usually the monster whose LOS we're trying to calculate
+    // (if mon->x == gridx, mon->y == gridy).
+    // Else, any monster trying to move around within this los field.
+    monsters *mons;
+
+    // The array to store the LOS values.
+    int los_field[LSIZE][LSIZE];
+};
+
 #endif