Cleaner reference handling for the following extern-scope netsynced mobj_t*.

- `skyboxcenterpnts` and `skyboxviewpnts`
    - P_InitSkyboxPoint`, which calls `P_SetTarget`
- `waypoint->mobj`
    - Make sure NULL before using `P_SetTarget` on
- `tubewaypoints`
    - Use `P_SetTarget`
    - Use `UINT32_MAX` for the invalid mobjnum, since 0 is a valid one.
- `waypointcap` and `kitemcap`
    - NULL before reset

Our international nightmare is over.

src/k_waypoint.c

@@ -1949,6 +1949,7 @@ static waypoint_t *K_MakeWaypoint(mobj_t *const mobj)
 	madewaypoint = &waypointheap[numwaypoints];
 	numwaypoints++;
 
+	madewaypoint->mobj = NULL;
 	P_SetTarget(&madewaypoint->mobj, mobj);
 
 	// Don't allow a waypoint that has its next ID set to itself to work

src/p_mobj.c

@@ -12557,6 +12557,21 @@ static mobj_t *P_MakeSoftwareCorona(mobj_t *mo, INT32 height)
 	return corona;
 }
 
+void P_InitSkyboxPoint(mobj_t *mobj, mapthing_t *mthing)
+{
+	mtag_t tag = Tag_FGet(&mthing->tags);
+	if (tag < 0 || tag > 15)
+	{
+		CONS_Debug(DBG_GAMELOGIC, "P_InitSkyboxPoint: Skybox ID %d of mapthing %s is not between 0 and 15!\n", tag, sizeu1((size_t)(mthing - mapthings)));
+		return;
+	}
+
+	if (mthing->args[0])
+		P_SetTarget(&skyboxcenterpnts[tag], mobj);
+	else
+		P_SetTarget(&skyboxviewpnts[tag], mobj);
+}
+
 static boolean P_MapAlreadyHasStarPost(mobj_t *mobj)
 {
 	thinker_t *th;
@@ -12602,17 +12617,7 @@ static boolean P_SetupSpawnedMapThing(mapthing_t *mthing, mobj_t *mobj, boolean
 	}
 	case MT_SKYBOX:
 	{
-		mtag_t tag = Tag_FGet(&mthing->tags);
+		P_InitSkyboxPoint(mobj, mthing);
-		if (tag < 0 || tag > 15)
-		{
-			CONS_Debug(DBG_GAMELOGIC, "P_SetupSpawnedMapThing: Skybox ID %d of mapthing %s is not between 0 and 15!\n", tag, sizeu1((size_t)(mthing - mapthings)));
-			break;
-		}
-
-		if (mthing->args[0])
-			skyboxcenterpnts[tag] = mobj;
-		else
-			skyboxviewpnts[tag] = mobj;
 		break;
 	}
 	case MT_EGGSTATUE:

src/p_saveg.c

@@ -1070,7 +1070,12 @@ static void P_NetArchiveTubeWaypoints(savebuffer_t *save)
 	{
 		WRITEUINT16(save->p, numtubewaypoints[i]);
 		for (j = 0; j < numtubewaypoints[i]; j++)
-			WRITEUINT32(save->p, tubewaypoints[i][j] ? tubewaypoints[i][j]->mobjnum : 0);
+		{
+			if (tubewaypoints[i][j])
+				WRITEUINT32(save->p, tubewaypoints[i][j]->mobjnum);
+			else
+				WRITEUINT32(save->p, UINT32_MAX);
+		}
 	}
 }
 
@@ -1085,7 +1090,9 @@ static void P_NetUnArchiveTubeWaypoints(savebuffer_t *save)
 		for (j = 0; j < numtubewaypoints[i]; j++)
 		{
 			mobjnum = READUINT32(save->p);
-			tubewaypoints[i][j] = (mobjnum == 0) ? NULL : P_FindNewPosition(mobjnum);
+			tubewaypoints[i][j] = NULL;
+			if (mobjnum != UINT32_MAX)
+				P_SetTarget(&tubewaypoints[i][j], P_FindNewPosition(mobjnum));
 		}
 	}
 }
@@ -3068,6 +3075,7 @@ static void P_NetUnArchiveWaypoints(savebuffer_t *save)
 			for (i = 0U; i < numArchiveWaypoints; i++) {
 				waypoint = K_GetWaypointFromIndex(i);
 				temp = READUINT32(save->p);
+				waypoint->mobj = NULL;
 				if (!P_SetTarget(&waypoint->mobj, P_FindNewPosition(temp))) {
 					CONS_Debug(DBG_GAMELOGIC, "waypoint mobj not found for %d\n", i);
 				}
@@ -3453,17 +3461,9 @@ static thinker_t* LoadMobjThinker(savebuffer_t *save, actionf_p1 thinker)
 			mobj->player->viewz = mobj->player->mo->z + mobj->player->viewheight;
 	}
 
-	if (mobj->type == MT_SKYBOX)
+	if (mobj->type == MT_SKYBOX && mobj->spawnpoint)
 	{
-		mtag_t tag = mobj->movedir;
+		P_InitSkyboxPoint(mobj, mobj->spawnpoint);
-		if (tag < 0 || tag > 15)
-		{
-			CONS_Debug(DBG_GAMELOGIC, "LoadMobjThinker: Skybox ID %d of netloaded object is not between 0 and 15!\n", tag);
-		}
-		else if (mobj->flags2 & MF2_AMBUSH)
-			skyboxcenterpnts[tag] = mobj;
-		else
-			skyboxviewpnts[tag] = mobj;
 	}
 
 	if (diff2 & MD2_WAYPOINTCAP)
@@ -4105,6 +4105,13 @@ static void P_NetUnArchiveThinkers(savebuffer_t *save)
 	iquetail = iquehead = 0;
 	P_InitThinkers();
 
+	// Oh my god don't blast random memory with our reference counts.
+	waypointcap = kitemcap = NULL;
+	for (i = 0; i <= 15; i++)
+	{
+		skyboxcenterpnts[i] = skyboxviewpnts[i] = NULL;
+	}
+
 	// clear sector thinker pointers so they don't point to non-existant thinkers for all of eternity
 	for (i = 0; i < numsectors; i++)
 	{

src/p_setup.c

@@ -184,7 +184,7 @@ UINT16 numtubewaypoints[NUMTUBEWAYPOINTSEQUENCES];
 
 void P_AddTubeWaypoint(UINT8 sequence, UINT8 id, mobj_t *waypoint)
 {
-	tubewaypoints[sequence][id] = waypoint;
+	P_SetTarget(&tubewaypoints[sequence][id], waypoint);
 	if (id >= numtubewaypoints[sequence])
 		numtubewaypoints[sequence] = id + 1;
 }

src/p_spec.h

@@ -24,6 +24,8 @@ extern "C" {
 extern mobj_t *skyboxviewpnts[16]; // array of MT_SKYBOX viewpoint mobjs
 extern mobj_t *skyboxcenterpnts[16]; // array of MT_SKYBOX centerpoint mobjs
 
+void P_InitSkyboxPoint(mobj_t *mobj, mapthing_t *mthing);
+
 // Amount (dx, dy) vector linedef is shifted right to get scroll amount
 #define SCROLL_SHIFT 5