From eac69ada2be42fb8da7248d8e298b1d9e795364a Mon Sep 17 00:00:00 2001
From: Kevin Granade <kevin.granade@gmail.com>
Date: Mon, 10 Jun 2019 05:42:50 +0000
Subject: [PATCH 1/2] Only recalculate seen cache when necessary.

---
 src/lightmap.cpp |  5 +++--
 src/map.cpp      | 18 ++++++++++++------
 src/map.h        |  8 ++++++--
 3 files changed, 21 insertions(+), 10 deletions(-)

diff --git a/src/lightmap.cpp b/src/lightmap.cpp
index 9c7b9ee99da2d..552ed6302b56a 100644
--- a/src/lightmap.cpp
+++ b/src/lightmap.cpp
@@ -80,14 +80,14 @@ void map::add_light_from_items( const tripoint &p, std::list<item>::iterator beg
 }
 
 // TODO: Consider making this just clear the cache and dynamically fill it in as trans() is called
-void map::build_transparency_cache( const int zlev )
+bool map::build_transparency_cache( const int zlev )
 {
     auto &map_cache = get_cache( zlev );
     auto &transparency_cache = map_cache.transparency_cache;
     auto &outside_cache = map_cache.outside_cache;
 
     if( !map_cache.transparency_cache_dirty ) {
-        return;
+        return false;
     }
 
     // Default to just barely not transparent.
@@ -167,6 +167,7 @@ void map::build_transparency_cache( const int zlev )
         }
     }
     map_cache.transparency_cache_dirty = false;
+    return true;
 }
 
 void map::apply_character_light( player &p )
diff --git a/src/map.cpp b/src/map.cpp
index 917c005b1036f..7b04df7af08c1 100644
--- a/src/map.cpp
+++ b/src/map.cpp
@@ -7782,11 +7782,11 @@ void map::build_obstacle_cache( const tripoint &start, const tripoint &end,
     }
 }
 
-void map::build_floor_cache( const int zlev )
+bool map::build_floor_cache( const int zlev )
 {
     auto &ch = get_cache( zlev );
     if( !ch.floor_cache_dirty ) {
-        return;
+        return false;
     }
 
     auto &floor_cache = ch.floor_cache;
@@ -7812,6 +7812,7 @@ void map::build_floor_cache( const int zlev )
     }
 
     ch.floor_cache_dirty = false;
+    return zlevels;
 }
 
 void map::build_floor_caches()
@@ -7827,10 +7828,11 @@ void map::build_map_cache( const int zlev, bool skip_lightmap )
 {
     const int minz = zlevels ? -OVERMAP_DEPTH : zlev;
     const int maxz = zlevels ? OVERMAP_HEIGHT : zlev;
+    bool seen_cache_dirty = false;
     for( int z = minz; z <= maxz; z++ ) {
         build_outside_cache( z );
-        build_transparency_cache( z );
-        build_floor_cache( z );
+        seen_cache_dirty |= build_transparency_cache( z );
+        seen_cache_dirty |= build_floor_cache( z );
     }
 
     tripoint start( 0, 0, minz );
@@ -7877,10 +7879,14 @@ void map::build_map_cache( const int zlev, bool skip_lightmap )
     const tripoint &p = g->u.pos();
     if( ( has_furn( p ) && !furn( p ).obj().transparent ) || !ter( p ).obj().transparent ) {
         get_cache( p.z ).transparency_cache[p.x][p.y] = LIGHT_TRANSPARENCY_CLEAR;
-        set_transparency_cache_dirty( p.z );
     }
 
-    build_seen_cache( g->u.pos(), zlev );
+    // Initial value is illegal player position.
+    static tripoint player_prev_pos = tripoint_zero;
+    if( seen_cache_dirty || player_prev_pos != p ) {
+        build_seen_cache( g->u.pos(), zlev );
+        player_prev_pos = p;
+    }
     if( !skip_lightmap ) {
         generate_lightmap( zlev );
     }
diff --git a/src/map.h b/src/map.h
index cbb3c5927cc96..8c7bbc5521369 100644
--- a/src/map.h
+++ b/src/map.h
@@ -1463,11 +1463,15 @@ class map
         void draw_connections( const oter_id &terrain_type, mapgendata &dat, const time_point &when,
                                const float density );
 
-        void build_transparency_cache( int zlev );
+        // Builds a transparency cache and returns true if the cache was invalidated.
+        // Used to determine if seen cache should be rebuilt.
+        bool build_transparency_cache( int zlev );
         void build_sunlight_cache( int zlev );
     public:
         void build_outside_cache( int zlev );
-        void build_floor_cache( int zlev );
+        // Builds a floor cache and returns true if the cache was invalidated.
+        // Used to determine if seen cache should be rebuilt.
+        bool build_floor_cache( int zlev );
         // We want this visible in `game`, because we want it built earlier in the turn than the rest
         void build_floor_caches();
 

From 951503fbc601e22a0babe1f61ddf0a9e8d71a8a3 Mon Sep 17 00:00:00 2001
From: Kevin Granade <kevin.granade@gmail.com>
Date: Mon, 10 Jun 2019 05:43:15 +0000
Subject: [PATCH 2/2] Remove some unecessary cache invalidations

---
 src/game.cpp          | 2 --
 src/handle_action.cpp | 1 -
 2 files changed, 3 deletions(-)

diff --git a/src/game.cpp b/src/game.cpp
index 6618bbd7d7dfc..474a0b9403c36 100644
--- a/src/game.cpp
+++ b/src/game.cpp
@@ -1501,7 +1501,6 @@ bool game::do_turn()
     sounds::process_sounds();
     // Update vision caches for monsters. If this turns out to be expensive,
     // consider a stripped down cache just for monsters.
-    m.invalidate_map_cache( get_levz() );
     m.build_map_cache( get_levz(), true );
     monmove();
     if( calendar::once_every( 3_minutes ) ) {
@@ -3148,7 +3147,6 @@ void game::draw()
 
     //temporary fix for updating visibility for minimap
     ter_view_z = ( u.pos() + u.view_offset ).z;
-    m.invalidate_map_cache( ter_view_z );
     m.build_map_cache( ter_view_z );
     m.update_visibility_cache( ter_view_z );
 
diff --git a/src/handle_action.cpp b/src/handle_action.cpp
index 4d3d94f7a4f1d..9b8189e5a3ec0 100644
--- a/src/handle_action.cpp
+++ b/src/handle_action.cpp
@@ -1951,7 +1951,6 @@ bool game::handle_action()
                     add_msg( m_info, _( "You can't disassemble items while you're riding." ) );
                 } else {
                     u.disassemble();
-                    g->m.invalidate_map_cache( g->get_levz() );
                     refresh_all();
                 }
                 break;