From c9700c6960195798bae63f9ef0ed9e0ff6a1e80b Mon Sep 17 00:00:00 2001
From: Mark Langsdorf <mark.langsdorf@gmail.com>
Date: Thu, 14 Nov 2019 18:39:32 -0600
Subject: [PATCH] map: properly rotate NPCs during update_mapgen

Fixes #35430

When a tinymap is rotated during update_mapgen, the NPCs would be moved
via spawn_at_precise, which would clip their position to 0-11,0-11,
effectively teleporting them to the upper left of the reality bubble.

Rework rotate() to include a variable as to whether the rotation is
setpos() safe, and use setpos() to relocate NPCs because that doesn't
clip the position and teleport the NPCs.
---
 src/map.h      |  6 +++++-
 src/mapgen.cpp | 32 ++++++++++++++++++++++----------
 2 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/src/map.h b/src/map.h
index a8788221e19b6..3faea041fbeae 100644
--- a/src/map.h
+++ b/src/map.h
@@ -1336,8 +1336,12 @@ class map
         }
 
         // Not protected/private for mapgen_functions.cpp access
-        void rotate( int turns ); // Rotates the current map 90*turns degrees clockwise
+        // Rotates the current map 90*turns degrees clockwise
         // Useful for houses, shops, etc
+        // @param turns number of 90 clockwise turns to make
+        // @param setpos_safe if true, being used outside of mapgen and can use setpos to
+        // set NPC positions.  if false, cannot use setpos
+        void rotate( int turns, bool setpos_safe = false );
 
         // Monster spawning:
     public:
diff --git a/src/mapgen.cpp b/src/mapgen.cpp
index e49359e4f7302..18ecd0c75c42f 100644
--- a/src/mapgen.cpp
+++ b/src/mapgen.cpp
@@ -6684,7 +6684,7 @@ computer *map::add_computer( const tripoint &p, const std::string &name, int sec
  * degrees.
  * @param turns How many 90-degree turns to rotate the map.
  */
-void map::rotate( int turns )
+void map::rotate( int turns, const bool setpos_safe )
 {
 
     //Handle anything outside the 1-3 range gracefully; rotate(0) is a no-op.
@@ -6704,6 +6704,8 @@ void map::rotate( int turns )
     for( const std::shared_ptr<npc> &i : npcs ) {
         npc &np = *i;
         const tripoint sq = np.global_square_location();
+        const point local_sq = getlocal( sq ).xy();
+
         real_coords np_rc;
         np_rc.fromabs( sq.x, sq.y );
         // Note: We are rotating the entire overmap square (2x2 of submaps)
@@ -6714,7 +6716,6 @@ void map::rotate( int turns )
         // OK, this is ugly: we remove the NPC from the whole map
         // Then we place it back from scratch
         // It could be rewritten to utilize the fact that rotation shouldn't cross overmaps
-        auto npc_ptr = overmap_buffer.remove_npc( np.getID() );
 
         int old_x = np_rc.sub_pos.x;
         int old_y = np_rc.sub_pos.y;
@@ -6725,10 +6726,22 @@ void map::rotate( int turns )
             old_y += SEEY;
         }
 
-        const auto new_pos = point{ old_x, old_y } .rotate( turns, { SEEX * 2, SEEY * 2 } );
-
-        np.spawn_at_precise( { abs_sub.xy() }, { new_pos, abs_sub.z } );
-        overmap_buffer.insert_npc( npc_ptr );
+        const point new_pos = point{ old_x, old_y } .rotate( turns, { SEEX * 2, SEEY * 2 } );
+        if( setpos_safe ) {
+            // setpos can't be used during mapgen, but spawn_at_precise clips position
+            // to be between 0-11,0-11 and teleports NPCs when used inside of update_mapgen
+            // calls
+            const tripoint new_global_sq = sq - local_sq + new_pos;
+            const tripoint &new_local_pos = g->m.getlocal( new_global_sq );
+            np.setpos( tripoint( new_local_pos ) );
+        } else {
+            // OK, this is ugly: we remove the NPC from the whole map
+            // Then we place it back from scratch
+            // It could be rewritten to utilize the fact that rotation shouldn't cross overmaps
+            std::shared_ptr<npc> npc_ptr = overmap_buffer.remove_npc( np.getID() );
+            np.spawn_at_precise( { abs_sub.xy() }, { new_pos, abs_sub.z } );
+            overmap_buffer.insert_npc( npc_ptr );
+        }
     }
 
     clear_vehicle_cache( abs_sub.z );
@@ -7702,15 +7715,14 @@ bool update_mapgen_function_json::update_map( const tripoint &omt_pos, const poi
     tinymap update_tmap;
     const tripoint sm_pos = omt_to_sm_copy( omt_pos );
     update_tmap.load( sm_pos, false );
-    const std::string map_id = overmap_buffer.ter( omt_pos ).id().c_str();
 
     mapgendata md( omt_pos, update_tmap, 0.0f, calendar::start_of_cataclysm, miss );
 
     // If the existing map is rotated, we need to rotate it back to the north
     // orientation before applying our updates.
-    int rotation = oter_get_rotation( overmap_buffer.ter( omt_pos ) );
+    const int rotation = oter_get_rotation( overmap_buffer.ter( omt_pos ) );
     if( rotation > 0 ) {
-        md.m.rotate( rotation );
+        md.m.rotate( rotation, true );
     }
 
     const bool applied = update_map( md, offset, verify );
@@ -7718,7 +7730,7 @@ bool update_mapgen_function_json::update_map( const tripoint &omt_pos, const poi
     // If we rotated the map before applying updates, we now need to rotate
     // it back to where we found it.
     if( rotation ) {
-        md.m.rotate( 4 - rotation );
+        md.m.rotate( 4 - rotation, true );
     }
 
     if( applied ) {