add a "prev map" key binding (#2046)

* add a "prev map" key binding

Fixes #2007

* simplify

* add safety measures

* simplify again

* fix

* simplify logic

* add to key binding menu instead of player specific chat keys

* start with gamemap 99 when crossing gameepisodes

* start new episode with gamemap = cur_map to allow a full gamemap circle

* fix UMAPINFO

* reset gamemap outside the while() condition

* do not let linear and UMAPINFO maps cross

* prevent G_GotoNextLevel() from cycling across levels that end the game

* check either UMAPINFO or linear progression in G_GotoNextLevel()

* don't report the map we couldn't find, but the map that we couldn't find a previous map for

src/g_game.c

@@ -1076,12 +1076,12 @@ int G_GotoNextLevel(int *pEpi, int *pMap)
     {12, 13, 19, 15, 16, 17, 18, 21, 14},
     {22, 23, 24, 25, 29, 27, 28, 31, 26},
     {32, 33, 34, 35, 36, 39, 38, 41, 37},
-    {42, 49, 44, 45, 46, 47, 48, 11, 43}
+    {42, 49, 44, 45, 46, 47, 48, -1, 43}
   };
   byte doom2_next[32] = {
      2,  3,  4,  5,  6,  7,  8,  9, 10, 11,
     12, 13, 14, 15, 31, 17, 18, 19, 20, 21,
-    22, 23, 24, 25, 26, 27, 28, 29, 30,  1,
+    22, 23, 24, 25, 26, 27, 28, 29, 30, -1,
     32, 16
   };
 
@@ -1096,25 +1096,19 @@ int G_GotoNextLevel(int *pEpi, int *pMap)
       next = gamemapinfo->nextsecret;
     else if (gamemapinfo->nextmap[0])
       next = gamemapinfo->nextmap;
-    else if (gamemapinfo->flags & MapInfo_EndGame)
-    {
-      epsd = 1;
-      map = 1;
-    }
 
     if (next)
       G_ValidateMapName(next, &epsd, &map);
   }
-
+  else
-  if (map == -1)
   {
     // secret level
     doom2_next[14] = (haswolflevels ? 31 : 16);
 
     // shareware doom has only episode 1
-    doom_next[0][7] = (gamemode == shareware ? 11 : 21);
+    doom_next[0][7] = (gamemode == shareware ? -1 : 21);
 
-    doom_next[2][7] = (gamemode == registered ? 11 : 41);
+    doom_next[2][7] = (gamemode == registered ? -1 : 41);
 
     //doom2_next and doom_next are 0 based, unlike gameepisode and gamemap
     epsd = gameepisode - 1;
@@ -1159,8 +1153,11 @@ int G_GotoNextLevel(int *pEpi, int *pMap)
   {
     char *name = MapName(epsd, map);
 
-    if (W_CheckNumForName(name) == -1)
+    if (map == -1 || W_CheckNumForName(name) == -1)
-      displaymsg("Next level not found: %s", name);
+    {
+      name = MapName(gameepisode, gamemap);
+      displaymsg("Next level not found for %s", name);
+    }
     else
     {
       G_DeferedInitNew(gameskill, epsd, map);
@@ -1171,6 +1168,66 @@ int G_GotoNextLevel(int *pEpi, int *pMap)
   return false;
 }
 
+int G_GotoPrevLevel(void)
+{
+    if (gamestate != GS_LEVEL || deathmatch || netgame || demorecording
+        || demoplayback || menuactive)
+    {
+        return false;
+    }
+
+    const int cur_epsd = gameepisode;
+    const int cur_map = gamemap;
+    struct mapentry_s *const cur_gamemapinfo = gamemapinfo;
+    int ret = false;
+
+    do
+    {
+        gamemap = cur_map;
+
+        while ((gamemap = (gamemap + 99) % 100) != cur_map)
+        {
+            int next_epsd, next_map;
+            gamemapinfo = G_LookupMapinfo(gameepisode, gamemap);
+            G_GotoNextLevel(&next_epsd, &next_map);
+
+            // do not let linear and UMAPINFO maps cross
+            if ((cur_gamemapinfo == NULL && gamemapinfo != NULL) ||
+                (cur_gamemapinfo != NULL && gamemapinfo == NULL))
+            {
+                continue;
+            }
+
+            if (next_epsd == cur_epsd && next_map == cur_map)
+            {
+                char *name = MapName(gameepisode, gamemap);
+
+                if (W_CheckNumForName(name) != -1)
+                {
+                    G_DeferedInitNew(gameskill, gameepisode, gamemap);
+                    ret = true;
+                    break;
+                }
+            }
+        }
+    } while (ret == false
+             // only check one episode in Doom 2
+             && gamemode != commercial
+             && (gameepisode = (gameepisode + 9) % 10) != cur_epsd);
+
+    gameepisode = cur_epsd;
+    gamemap = cur_map;
+    gamemapinfo = cur_gamemapinfo;
+
+    if (ret == false)
+    {
+        char *name = MapName(gameepisode, gamemap);
+        displaymsg("Previous level not found for %s", name);
+    }
+
+    return ret;
+}
+
 static boolean G_StrictModeSkipEvent(event_t *ev)
 {
   static boolean enable_mouse = false;

src/g_game.h

@@ -82,6 +82,7 @@ demo_version_t G_GetNamedComplevel(const char *arg);
 const char *G_GetCurrentComplevelName(void);
 
 int G_GotoNextLevel(int *pEpi, int *pMap);
+int G_GotoPrevLevel(void);
 
 void G_BindGameInputVariables(void);
 void G_BindGameVariables(void);

src/m_input.c

@@ -702,6 +702,7 @@ void M_BindInputVariables(void)
 
     BIND_INPUT(input_menu_reloadlevel, "Restart current level/demo");
     BIND_INPUT(input_menu_nextlevel, "Go to next level");
+    BIND_INPUT(input_menu_prevlevel, "Go to previous level");
 
     BIND_INPUT(input_hud_timestats, "Toggle display of level stats and time");
 

src/m_input.h

@@ -68,6 +68,7 @@ enum
     input_menu_clear,
     input_menu_reloadlevel,
     input_menu_nextlevel,
+    input_menu_prevlevel,
 
     input_hud_timestats,
 

src/mn_menu.c

@@ -2627,6 +2627,18 @@ boolean M_ShortcutResponder(const event_t *ev)
         }
     }
 
+    if (M_InputActivated(input_menu_prevlevel))
+    {
+        if (demoplayback && singledemo && !PLAYBACK_SKIP)
+        {
+            return false;
+        }
+        else if (G_GotoPrevLevel())
+        {
+            return true;
+        }
+    }
+
     if (M_InputActivated(input_demo_fforward))
     {
         if (demoplayback && !PLAYBACK_SKIP && !fastdemo && !D_CheckNetConnect())

src/mn_setup.c

@@ -1418,6 +1418,7 @@ static setup_menu_t keys_settings3[] = {
     // [FG] reload current level / go to next level
     {"Reload Map/Demo", S_INPUT, KB_X, M_SPC, {0}, m_scrn, input_menu_reloadlevel},
     {"Next Map",        S_INPUT, KB_X, M_SPC, {0}, m_scrn, input_menu_nextlevel},
+    {"Previous Map",    S_INPUT, KB_X, M_SPC, {0}, m_scrn, input_menu_prevlevel},
     {"Show Stats/Time", S_INPUT, KB_X, M_SPC, {0}, m_scrn, input_hud_timestats},
     MI_GAP,
     {"Fast-FWD Demo",   S_INPUT, KB_X, M_SPC, {0}, m_scrn, input_demo_fforward},
@@ -1428,10 +1429,6 @@ static setup_menu_t keys_settings3[] = {
     {"Default Speed",   S_INPUT, KB_X, M_SPC, {0}, m_scrn, input_speed_default},
     MI_GAP,
     {"Begin Chat",      S_INPUT, KB_X, M_SPC, {0}, m_scrn, input_chat},
-    {"Player 1",        S_INPUT, KB_X, M_SPC, {0}, m_scrn, input_chat_dest0},
-    {"Player 2",        S_INPUT, KB_X, M_SPC, {0}, m_scrn, input_chat_dest1},
-    {"Player 3",        S_INPUT, KB_X, M_SPC, {0}, m_scrn, input_chat_dest2},
-    {"Player 4",        S_INPUT, KB_X, M_SPC, {0}, m_scrn, input_chat_dest3},
     MI_END
 };