Improve performance in npc::has_potential_los (CleverRaven#76009)

src/map.cpp

@@ -7776,18 +7776,19 @@ bool map::sees( const tripoint_bub_ms &F, const tripoint_bub_ms &T, const int ra
     return sees( F.raw(), T.raw(), range, dummy, with_fields );
 }
 
-point map::sees_cache_key( const tripoint_bub_ms &from, const tripoint_bub_ms &to ) const
+// TODO: Change this to a hash function on the map implementation. This will also allow us to
+// account for the complete lack of entropy in the top 16 bits.
+int64_t map::sees_cache_key( const tripoint_bub_ms &from, const tripoint_bub_ms &to ) const
 {
-
     // Canonicalize the order of the tripoints so the cache is reflexive.
     const tripoint_bub_ms &min = from < to ? from : to;
     const tripoint_bub_ms &max = !( from < to ) ? from : to;
 
-    // A little gross, just pack the values into a point.
-    return point(
-               min.x() << 16 | min.y() << 8 | ( min.z() + OVERMAP_DEPTH ),
-               max.x() << 16 | max.y() << 8 | ( max.z() + OVERMAP_DEPTH )
-           );
+    // A little gross, just pack the values into an integer.
+    return
+        static_cast<int64_t>( min.x() )  << 50 | static_cast<int64_t>( min.y() ) << 40 |
+        ( static_cast<int64_t>( min.z() ) + OVERMAP_DEPTH ) << 30 | max.x() << 20 | max.y() << 10 |
+        ( max.z() + OVERMAP_DEPTH );
 }
 
 /**
@@ -7811,10 +7812,10 @@ bool map::sees( const tripoint_bub_ms &F, const tripoint_bub_ms &T, const int ra
         bresenham_slope = 0;
         return false; // Out of range!
     }
-    const point key = sees_cache_key( F, T );
+    const int64_t key = sees_cache_key( F, T );
     if( allow_cached ) {
         char cached = skew_cache.get( key, -1 );
-        if( cached >= 0 ) {
+        if( cached != -1 ) {
             return cached > 0;
         }
     }
@@ -11115,9 +11116,9 @@ void map::invalidate_max_populated_zlev( int zlev )
 
 bool map::has_potential_los( const tripoint_bub_ms &from, const tripoint_bub_ms &to ) const
 {
-    const point key = sees_cache_key( from, to );
+    const int64_t key = sees_cache_key( from, to );
     char cached = skew_vision_cache.get( key, -1 );
-    if( cached >= 0 ) {
+    if( cached != -1 ) {
         return cached > 0;
     }
     return true;

src/map.h

@@ -702,7 +702,7 @@ class map
                    bool with_fields = true ) const;
         bool sees( const tripoint_bub_ms &F, const tripoint_bub_ms &T, int range, int &bresenham_slope,
                    bool with_fields = true, bool allow_cached = true ) const;
-        point sees_cache_key( const tripoint_bub_ms &from, const tripoint_bub_ms &to ) const;
+        int64_t sees_cache_key( const tripoint_bub_ms &from, const tripoint_bub_ms &to ) const;
     public:
         /**
         * Returns coverage of target in relation to the observer. Target is loc2, observer is loc1.
@@ -2602,7 +2602,7 @@ class map
         /**
          * Cache of coordinate pairs recently checked for visibility.
          */
-        using lru_cache_t = lru_cache<point, char>;
+        using lru_cache_t = lru_cache<int64_t, char>;
         mutable lru_cache_t skew_vision_cache;
         mutable lru_cache_t skew_vision_wo_fields_cache;