Encapsulate lum

src/lightmap.cpp

@@ -317,7 +317,7 @@ void map::generate_lightmap( const int zlev )
                         }
                     }
 
-                    if( cur_submap->lum[sx][sy] && has_items( p ) ) {
+                    if( cur_submap->get_lum( { sx, sy } ) && has_items( p ) ) {
                         auto items = i_at( p );
                         add_light_from_items( p, items.begin(), items.end() );
                     }

src/map.cpp

@@ -3942,7 +3942,7 @@ void map::i_clear( const tripoint &p )
         submaps_with_active_items.erase( tripoint( abs_sub.x + p.x / SEEX, abs_sub.y + p.y / SEEY, p.z ) );
     }
 
-    current_submap->lum[l.x][l.y] = 0;
+    current_submap->set_lum( l, 0 );
     current_submap->itm[l.x][l.y].clear();
 }
 

src/submap.h

@@ -110,6 +110,15 @@ class submap : public maptile_soa<SEEX, SEEY>    // TODO: Use private inheritanc
             rad[p.x][p.y] = radiation;
         }
 
+        uint8_t get_lum( const point &p ) const {
+            return lum[p.x][p.y];
+        }
+
+        void set_lum( const point &p, uint8_t luminance ) {
+            is_uniform = false;
+            lum[p.x][p.y] = luminance;
+        }
+
         void update_lum_add( const point &p, const item &i ) {
             is_uniform = false;
             if( i.is_emissive() && lum[p.x][p.y] < 255 ) {