Separate caches for light and vision transparency

Crouching affects your ability to see past adjacent obstacles.
Previously this was implemented by altering the transparency cache.
However, this also stops light passing the tile, and means that
crouching by a window can cause a room to fall dark.

Fix by separating the transparency cache into two, one for light and one
for vision.  The latter is a copy of the former, except with tweaks for
crouching and with the avatar's tile forced to be transparent.

src/lightmap.cpp

@@ -143,6 +143,40 @@ bool map::build_transparency_cache( const int zlev )
     return true;
 }
 
+bool map::build_vision_transparency_cache( const int zlev )
+{
+    auto &map_cache = get_cache( zlev );
+    auto &transparency_cache = map_cache.transparency_cache;
+    auto &vision_transparency_cache = map_cache.vision_transparency_cache;
+
+    memcpy( &vision_transparency_cache, &transparency_cache, sizeof( transparency_cache ) );
+
+    const tripoint &p = g->u.pos();
+
+    if( p.z != zlev ) {
+        return false;
+    }
+
+    bool dirty = false;
+
+    bool is_crouching = g->u.movement_mode_is( CMM_CROUCH );
+    for( const tripoint &loc : points_in_radius( p, 1 ) ) {
+        if( loc == p ) {
+            // The tile player is standing on should always be visible
+            if( ( has_furn( p ) && !furn( p )->transparent ) || !ter( p )->transparent ) {
+                vision_transparency_cache[p.x][p.y] = LIGHT_TRANSPARENCY_CLEAR;
+            }
+        } else if( is_crouching && coverage( loc ) >= 30 ) {
+            // If we're crouching behind an obstacle, we can't see past it.
+            vision_transparency_cache[loc.x][loc.y] = LIGHT_TRANSPARENCY_SOLID;
+            map_cache.transparency_cache_dirty = true;
+            dirty = true;
+        }
+    }
+
+    return dirty;
+}
+
 void map::apply_character_light( player &p )
 {
     if( p.has_effect( effect_onfire ) ) {
@@ -1102,7 +1136,7 @@ castLightAll<fragment_cloud, fragment_cloud, shrapnel_calc, shrapnel_check,
 void map::build_seen_cache( const tripoint &origin, const int target_z )
 {
     auto &map_cache = get_cache( target_z );
-    float ( &transparency_cache )[MAPSIZE_X][MAPSIZE_Y] = map_cache.transparency_cache;
+    float ( &transparency_cache )[MAPSIZE_X][MAPSIZE_Y] = map_cache.vision_transparency_cache;
     float ( &seen_cache )[MAPSIZE_X][MAPSIZE_Y] = map_cache.seen_cache;
     float ( &camera_cache )[MAPSIZE_X][MAPSIZE_Y] = map_cache.camera_cache;
 
@@ -1125,7 +1159,7 @@ void map::build_seen_cache( const tripoint &origin, const int target_z )
         array_of_grids_of<const bool> floor_caches;
         for( int z = -OVERMAP_DEPTH; z <= OVERMAP_HEIGHT; z++ ) {
             auto &cur_cache = get_cache( z );
-            transparency_caches[z + OVERMAP_DEPTH] = &cur_cache.transparency_cache;
+            transparency_caches[z + OVERMAP_DEPTH] = &cur_cache.vision_transparency_cache;
             seen_caches[z + OVERMAP_DEPTH] = &cur_cache.seen_cache;
             floor_caches[z + OVERMAP_DEPTH] = &cur_cache.floor_cache;
             std::uninitialized_fill_n(

src/map.cpp

@@ -7714,33 +7714,19 @@ void map::build_map_cache( const int zlev, bool skip_lightmap )
     for( int z = minz; z <= maxz; z++ ) {
         build_outside_cache( z );
         seen_cache_dirty |= build_transparency_cache( z );
+        seen_cache_dirty |= build_vision_transparency_cache( zlev );
         seen_cache_dirty |= build_floor_cache( z );
         do_vehicle_caching( z );
     }
 
-    const tripoint &p = g->u.pos();
-    bool is_crouching = g->u.movement_mode_is( CMM_CROUCH );
-    for( const tripoint &loc : points_in_radius( p, 1 ) ) {
-        if( loc == p ) {
-            // The tile player is standing on should always be transparent
-            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;
-            }
-        } else if( is_crouching && coverage( loc ) >= 30 ) {
-            // If we're crouching behind an obstacle, we can't see past it.
-            get_cache( loc.z ).transparency_cache[loc.x][loc.y] = LIGHT_TRANSPARENCY_SOLID;
-            get_cache( loc.z ).transparency_cache_dirty = true;
-            seen_cache_dirty = true;
-        }
-    }
-
     if( seen_cache_dirty ) {
         skew_vision_cache.clear();
     }
     // Initial value is illegal player position.
+    const tripoint &p = g->u.pos();
     static tripoint player_prev_pos;
     if( seen_cache_dirty || player_prev_pos != p ) {
-        build_seen_cache( g->u.pos(), zlev );
+        build_seen_cache( p, zlev );
         player_prev_pos = p;
     }
     if( !skip_lightmap ) {
@@ -8239,6 +8225,7 @@ level_cache::level_cache()
     std::fill_n( &outside_cache[0][0], map_dimensions, false );
     std::fill_n( &floor_cache[0][0], map_dimensions, false );
     std::fill_n( &transparency_cache[0][0], map_dimensions, 0.0f );
+    std::fill_n( &vision_transparency_cache[0][0], map_dimensions, 0.0f );
     std::fill_n( &seen_cache[0][0], map_dimensions, 0.0f );
     std::fill_n( &camera_cache[0][0], map_dimensions, 0.0f );
     std::fill_n( &visibility_cache[0][0], map_dimensions, LL_DARK );

src/map.h

@@ -170,6 +170,7 @@ struct level_cache {
     bool outside_cache[MAPSIZE_X][MAPSIZE_Y];
     bool floor_cache[MAPSIZE_X][MAPSIZE_Y];
     float transparency_cache[MAPSIZE_X][MAPSIZE_Y];
+    float vision_transparency_cache[MAPSIZE_X][MAPSIZE_Y];
     float seen_cache[MAPSIZE_X][MAPSIZE_Y];
     float camera_cache[MAPSIZE_X][MAPSIZE_Y];
     lit_level visibility_cache[MAPSIZE_X][MAPSIZE_Y];
@@ -1559,6 +1560,7 @@ class map
         // 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 );
+        bool build_vision_transparency_cache( int zlev );
         void build_sunlight_cache( int zlev );
     public:
         void build_outside_cache( int zlev );