Reimplement over_under with code from DSDA

CHANGELOG.md

@@ -4,9 +4,14 @@
 
 ## Changes
 
+- **Reimplemented _Move Over/Under Things_ feature**¹, making it much less bug-prone
 - **Improved Automap line thickening when the window is downscaled**
 - **Tweaked zooming effect**
 
+**1\.** Among other changes, the setting itself has been extended: a value of `1` enables the feature only for players,
+while a value of `2` enables it for all Things. This differs from the previous implementation, wherein `1` would enable
+the feature for all Things.
+
 ## Bug Fixes
 
 - **FOV effects not being cleared thoroughly upon loading levels**

README.md

@@ -39,7 +39,7 @@ For these settings, their CVAR names are provided alongside the _CFG-Only_ label
 - **Extended _Level Brightness_ range:** [-8, 8]
 - **_"Direct + Auto"_ mode for Vertical Aiming**
 - **_Direct Vertical Aiming_ for melee attacks**
-- **_Things move over/under things_** setting [p.f. Crispy Doom]
+- **_Move Over/Under Things_** setting [partially p.f. Crispy Doom, DSDA-Doom]
 - **Jumping** (default key: <kbd>Alt</kbd>, must be enabled first) [p.f. Crispy Doom]
 - **Crouching/ducking** (default key: <kbd>C</kbd>, must be enabled first) [i.b. ZDoom]
 - **_Field of View_** setting [p.f. Doom Retro]

src/m_menu.c

@@ -4892,6 +4892,10 @@ static void M_ChangeViewHeight(void)
   oldviewheight = viewheight_value;
 }
 
+static const char *over_under_str[] = {
+  "Off", "Player Only", "All Things", NULL
+};
+
 static const char *impact_pitch_str[] = {
   "Off", "Fall", "Damage", "Both", NULL
 };
@@ -4904,8 +4908,8 @@ setup_menu_t gen_settings6[] = {
 
   {"Nugget - Gameplay", S_SKIP|S_TITLE, m_null, M_X, M_Y + gen6_title1 * M_SPC},
 
-    {"Things Move Over/Under Things", S_YESNO|S_STRICT|S_CRITICAL, m_null, M_X, M_Y + gen6_overunder   * M_SPC, {"over_under"}},
-    {"Allow Jumping/Crouching",       S_YESNO|S_STRICT|S_CRITICAL, m_null, M_X, M_Y + gen6_jump_crouch * M_SPC, {"jump_crouch"}},
+    {"Move Over/Under Things",        S_CHOICE|S_STRICT|S_CRITICAL, m_null, M_X, M_Y + gen6_overunder   * M_SPC, {"over_under"}, 0, NULL, over_under_str},
+    {"Allow Jumping/Crouching",       S_YESNO |S_STRICT|S_CRITICAL, m_null, M_X, M_Y + gen6_jump_crouch * M_SPC, {"jump_crouch"}},
 
   {"",              S_SKIP,         m_null, M_X, M_Y + gen6_stub1  * M_SPC},
   {"Nugget - View", S_SKIP|S_TITLE, m_null, M_X, M_Y + gen6_title2 * M_SPC},

src/m_misc.c

@@ -721,8 +721,8 @@ default_t defaults[] = {
   {
     "over_under",
     (config_t *) &over_under, NULL,
-    {0}, {0,1}, number, ss_gen, wad_yes,
-    "1 to allow things to move over/under other things"
+    {0}, {0,2}, number, ss_gen, wad_yes,
+    "Allow movement over/under things (1 = Player only, 2 = All things)"
   },
 
   {

src/p_enemy.c

@@ -407,14 +407,38 @@ static boolean P_Move(mobj_t *actor, boolean dropoff) // killough 9/12/98
 
       if (actor->flags & MF_FLOAT && floatok)
         {
+          // [Nugget] Over/Under
+          const fixed_t oldz = actor->z;
+
           if (actor->z < tmfloorz)          // must adjust height
-            actor->z += FLOATSPEED;
+          {
+              actor->z += FLOATSPEED;
+
+              // [Nugget] Over/Under: don't ascend into other things
+              if (actor->above_thing
+                  && (actor->above_thing->z < (actor->z + actor->height)))
+              {
+                actor->z = actor->above_thing->z - actor->height;
+              }
+          }
           else
+          {
             actor->z -= FLOATSPEED;
 
-          actor->flags |= MF_INFLOAT;
+            // [Nugget] Over/Under: don't descend into other things
+            if (actor->below_thing
+                && (actor->z < (actor->below_thing->z + actor->below_thing->height)))
+            {
+              actor->z = actor->below_thing->z + actor->below_thing->height;
+            }
+          }
 
-	  return true;
+          // [Nugget] Conditions: only if we actually moved
+          if (NOTCASUALPLAY(actor->z != oldz))
+          {
+            actor->flags |= MF_INFLOAT;
+            return true;
+          }
         }
 
       if (!numspechit)
@@ -460,8 +484,14 @@ static boolean P_Move(mobj_t *actor, boolean dropoff) // killough 9/12/98
 
   // killough 11/98: fall more slowly, under gravity, if felldown==true
   if (!(actor->flags & MF_FLOAT) && (!felldown || demo_version < 203))
+  {
     actor->z = actor->floorz;
 
+    // [Nugget] Over/Under
+    if (actor->below_thing)
+    { actor->z = MAX(actor->floorz, actor->below_thing->z + actor->below_thing->height); }
+  }
+
   return true;
 }