Changes to setting position of things in map

More testing is required, but this hopefully will fix issue #55...

src/p_map.c

@@ -2065,8 +2065,12 @@ void P_CreateSecNodeList(mobj_t *thing, fixed_t x, fixed_t y)
     // added or verified as needed, m_thing will be set properly. When
     // finished, delete all nodes where m_thing is still NULL. These
     // represent the sectors the Thing has vacated.
-    for (node = thing->old_sectorlist; node; node = node->m_tnext)
+    node = sector_list;
+    while (node)
+    {
         node->m_thing = NULL;
+        node = node->m_tnext;
+    }
 
     tmthing = thing;
     tmflags = thing->flags;
@@ -2086,8 +2090,6 @@ void P_CreateSecNodeList(mobj_t *thing, fixed_t x, fixed_t y)
     yl = (tmbbox[BOXBOTTOM] - bmaporgy) >> MAPBLOCKSHIFT;
     yh = (tmbbox[BOXTOP] - bmaporgy) >> MAPBLOCKSHIFT;
 
-    sector_list = thing->old_sectorlist;
-
     for (bx = xl; bx <= xh; bx++)
         for (by = yl; by <= yh; by++)
             P_BlockLinesIterator(bx, by, PIT_GetSectors);

src/p_maputl.c

@@ -192,13 +192,13 @@ void P_UnsetThingPosition(mobj_t *thing)
     {
         // inert things don't need to be in blockmap?
         // unlink from subsector
-        if (thing->snext)
-            thing->snext->sprev = thing->sprev;
-
-        if (thing->sprev)
-            thing->sprev->snext = thing->snext;
-        else
-            thing->subsector->sector->thinglist = thing->snext;
+        //
+        // killough 8/11/98: simpler scheme using pointers-to-pointers for prev
+        // pointers, allows head node pointers to be treated like everything else
+        mobj_t  **sprev = thing->sprev;
+        mobj_t  *snext = thing->snext;
+        if ((*sprev = snext))                           // unlink from sector list
+            snext->sprev = sprev;
 
         // phares 3/14/98
         //
@@ -212,8 +212,8 @@ void P_UnsetThingPosition(mobj_t *thing)
         //
         // If this Thing is being removed entirely, then the calling
         // routine will clear out the nodes in sector_list.
-        thing->old_sectorlist = thing->touching_sectorlist;
-        thing->touching_sectorlist = NULL;      // to be restored by P_SetThingPosition
+        sector_list = thing->touching_sectorlist;
+        thing->touching_sectorlist = NULL;              // to be restored by P_SetThingPosition
     }
 
     if (!(thing->flags & MF_NOBLOCKMAP))
@@ -243,24 +243,22 @@ void P_UnsetThingPosition(mobj_t *thing)
 //
 void P_SetThingPosition(mobj_t *thing)
 {
-    subsector_t *ss;
-
     // link into subsector
-    ss = R_PointInSubsector(thing->x, thing->y);
-    thing->subsector = ss;
+    subsector_t *ss = thing->subsector = R_PointInSubsector(thing->x, thing->y);
 
     if (!(thing->flags & MF_NOSECTOR))
     {
         // invisible things don't go into the sector links
-        sector_t *sec = ss->sector;
-
-        thing->sprev = NULL;
-        thing->snext = sec->thinglist;
 
-        if (sec->thinglist)
-            sec->thinglist->sprev = thing;
+        // killough 8/11/98: simpler scheme using pointer-to-pointer prev
+        // pointers, allows head nodes to be treated like everything else
+        mobj_t  **link = &ss->sector->thinglist;
+        mobj_t  *snext = *link;
 
-        sec->thinglist = thing;
+        if ((thing->snext = snext))
+            snext->sprev = &thing->snext;
+        thing->sprev = link;
+        *link = thing;
 
         // phares 3/16/98
         //
@@ -276,7 +274,7 @@ void P_SetThingPosition(mobj_t *thing)
         // added, new sector links are created.
         P_CreateSecNodeList(thing, thing->x, thing->y);
         thing->touching_sectorlist = sector_list;       // Attach to Thing's mobj_t
-        thing->old_sectorlist = NULL;                   // clear for next time
+        sector_list = NULL;                             // clear for next time
     }
 
     // link into blockmap

src/p_mobj.c

@@ -679,11 +679,13 @@ void P_RemoveMobj(mobj_t *mobj)
     P_UnsetThingPosition(mobj);
 
     // Delete all nodes on the current sector_list
-    if (mobj->old_sectorlist)
-        P_DelSeclist(mobj->old_sectorlist);
+    if (sector_list)
+    {
+        P_DelSeclist(sector_list);
+        sector_list = NULL;
+    }
 
     mobj->flags |= (MF_NOSECTOR | MF_NOBLOCKMAP);
-    mobj->old_sectorlist = NULL;
 
     mobj->target = mobj->tracer = mobj->lastenemy = NULL;
 

src/p_mobj.h

@@ -279,17 +279,17 @@ typedef struct mobj_s
 
     // More list: links in sector (if needed)
     struct mobj_s       *snext;
-    struct mobj_s       *sprev;
+    struct mobj_s       **sprev;        // killough 8/10/98: change to ptr-to-ptr
 
     //More drawing info: to determine current sprite.
-    angle_t             angle;  // orientation
-    spritenum_t         sprite; // used to find patch_t and flip value
-    int                 frame;  // might be ORed with FF_FULLBRIGHT
+    angle_t             angle;          // orientation
+    spritenum_t         sprite;         // used to find patch_t and flip value
+    int                 frame;          // might be ORed with FF_FULLBRIGHT
 
     // Interaction info, by BLOCKMAP.
     // Links in blocks (if needed).
     struct mobj_s       *bnext;
-    struct mobj_s       **bprev; // killough 8/11/98: change to ptr-to-ptr
+    struct mobj_s       **bprev;        // killough 8/11/98: change to ptr-to-ptr
 
     struct subsector_s  *subsector;
 
@@ -315,9 +315,9 @@ typedef struct mobj_s
     int                 validcount;
 
     mobjtype_t          type;
-    mobjinfo_t          *info;  // &mobjinfo[mobj->type]
+    mobjinfo_t          *info;          // &mobjinfo[mobj->type]
 
-    int                 tics;   // state tic counter
+    int                 tics;           // state tic counter
     state_t             *state;
     int                 flags;
     int                 flags2;
@@ -362,9 +362,8 @@ typedef struct mobj_s
 
     // a linked list of sectors where this object appears
     struct msecnode_s   *touching_sectorlist;   // phares 3/14/98
-    struct msecnode_s   *old_sectorlist;        // haleyjd 04/16/10
 
-    short               gear; // killough 11/98: used in torque simulation
+    short               gear;           // killough 11/98: used in torque simulation
 
     int                 bloodsplats;
 

src/p_saveg.c

@@ -286,8 +286,8 @@ static void saveg_read_mobj_t(mobj_t *str)
     // struct mobj_s *snext
     str->snext = (mobj_t *)saveg_readp();
 
-    // struct mobj_s *sprev
-    str->sprev = (mobj_t *)saveg_readp();
+    // struct mobj_s **sprev
+    str->sprev = (mobj_t **)saveg_readp();
 
     // angle_t angle
     str->angle = saveg_read32();
@@ -400,9 +400,6 @@ static void saveg_read_mobj_t(mobj_t *str)
     // struct msecnode_s *touching_sectorlist
     str->touching_sectorlist = NULL;
 
-    // struct msecnode_s *old_sectorlist
-    str->old_sectorlist = NULL;
-
     // short gear
     str->gear = saveg_read16();