correct map issues clientside

but be loud about it instead of I_Error´ing
most of those would be fatal anyways, so screw vanilla desyncing if they crash eitherways

src/doomdata.h

@@ -81,10 +81,12 @@ typedef struct
 	INT16 flags;
 	INT16 special;
 	INT16 tag;
-	// sidenum[1] will be 0xffff if one sided
+	// sidenum[1] will be NO_INDEX if one sided
 	UINT16 sidenum[2];
 } ATTRPACK maplinedef_t;
 
+#define NO_INDEX 0xffff
+
 //
 // LineDef attributes.
 //

src/doomdef.h

@@ -602,6 +602,9 @@ extern const char *compdate, *comptime, *comprevision, *compbranch;
 // None of these that are disabled in the normal build are guaranteed to work perfectly
 // Compile them at your own risk!
 
+// undefine to enable fixes and features that are not vanilla compatible
+#define COMPAT_VANILLA
+
 //-- SATURN __
 /// Detect if a client is on Saturn in the clientconfig.
 /// To seperately allow them to join or block joining from vanilla clients.
@@ -666,6 +669,14 @@ extern const char *compdate, *comptime, *comprevision, *compbranch;
 #undef UPDATE_ALERT
 #endif
 
+// overwrite some of those
+// when not compiling in vanilla compat mode
+#ifndef COMPAT_VANILLA
+	#define SATURNJOIN
+	#define SATURNPAK
+	#undef SEENAMES
+#endif
+
 #ifdef __cplusplus
 } // extern "C"
 #endif

src/g_game.c

@@ -1309,6 +1309,7 @@ static void G_DoLoadLevel(boolean resetplayer)
 	{
 		// fail so reset game stuff
 		Command_ExitGame_f();
+		P_FreeCorruptMapWarnings();
 		return;
 	}
 
@@ -1342,6 +1343,8 @@ static void G_DoLoadLevel(boolean resetplayer)
 
 	// clear hud messages remains (usually from game startup)
 	CON_ClearHUD();
+	// print any map errors now due to clearhud above :chaosleep:
+	P_PrintCorruptMapWarnings();
 
 	server_lagless = !cv_gentlemens.value;
 

src/hardware/hw_bsp.c

@@ -373,7 +373,7 @@ static poly_t *CutOutSubsecPoly(seg_t *lseg, INT32 count, poly_t *poly)
 		if (!gl_maphashorizonlines && line->special == HORIZONSPECIAL)
 			gl_maphashorizonlines = true;
 
-		if (line->sidenum[1] != 0xffff)
+		if (line->sidenum[1] != NO_INDEX)
 		{
 			if (sides[line->sidenum[0]].sector == sides[line->sidenum[1]].sector)
 			{

src/hardware/hw_cache.c

@@ -729,7 +729,7 @@ static void HWR_PrecacheLevelTextures(void)
 		for (j = 0; j < 2; j++)
 		{
 			// check if single-sided linedef
-			if (line->sidenum[j] == 0xffff)
+			if (line->sidenum[j] == NO_INDEX)
 				continue;
 
 			const side_t *side = &sides[line->sidenum[j]];

src/lua_maplib.c

@@ -652,7 +652,7 @@ static int line_get(lua_State *L)
 		LUA_PushUserdata(L, &sides[line->sidenum[0]], META_SIDE);
 		return 1;
 	case line_backside: // backside
-		if (line->sidenum[1] == 0xffff)
+		if (line->sidenum[1] == NO_INDEX)
 			return 0;
 		LUA_PushUserdata(L, &sides[line->sidenum[1]], META_SIDE);
 		return 1;

src/p_maputl.cpp

@@ -242,7 +242,7 @@ void P_CameraLineOpening(line_t *linedef)
 	sector_t *back;
 	fixed_t frontfloor, frontceiling, backfloor, backceiling;
 
-	if (linedef->sidenum[1] == 0xffff)
+	if (linedef->sidenum[1] == NO_INDEX)
 	{
 		// single sided line
 		openrange = 0;
@@ -398,7 +398,7 @@ void P_LineOpening(line_t *linedef, mobj_t *mobj)
 {
 	sector_t *front, *back;
 
-	if (linedef->sidenum[1] == 0xffff)
+	if (linedef->sidenum[1] == NO_INDEX)
 	{
 		// single sided line
 		openrange = 0;
@@ -972,6 +972,10 @@ boolean P_BlockLinesIterator(INT32 x, INT32 y, boolean (*func)(line_t *))
 	// First index is really empty, so +1 it.
 	for (list = blockmaplump + offset + 1; *list != -1; list++)
 	{
+#ifdef RANGECHECK
+		if (*list < 0 || (UINT32)*list >= numlines)
+			I_Error("P_BlockLinesIterator: index >= numlines");
+#endif
 		ld = &lines[*list];
 
 		if (ld->validcount == validcount)

src/p_mobj.c

@@ -11029,7 +11029,11 @@ void P_SpawnMapThing(mapthing_t *mthing)
 	{
 		if (mthing->type > MAXPLAYERS) // be wary of playerstarts size!  playerstarts[MAXPLAYERS]
 		{
+#ifdef COMPAT_VANILLA
 			CONS_Alert(CONS_ERROR, "Excess player start detected %d This will crash vanilla clients!\n", mthing->type);
+#else
+			CONS_Debug(DBG_SETUP, "Excess player start detected %d\n", mthing->type);
+#endif
 		}
 		else
 		{
@@ -11280,7 +11284,11 @@ void P_SpawnMapThing(mapthing_t *mthing)
 
 	if (P_MobjWasRemoved(mobj))
 	{
+#ifdef COMPAT_VANILLA
 		CONS_Alert(CONS_ERROR, "Failed to spawn map thing #%d at %d, %d. This will crash vanilla clients!\n", mthing->type, x>>FRACBITS, y>>FRACBITS);
+#else
+		CONS_Debug(DBG_SETUP, "Failed to spawn map thing #%d at %d, %d.\n", mthing->type, x>>FRACBITS, y>>FRACBITS);
+#endif
 		return;
 	}
 

src/p_saveg.c

@@ -691,7 +691,7 @@ static void ArchiveLines(savebuffer_t *save)
 		if (spawnli->special == 321 || spawnli->special == 322) // only reason li->callcount would be non-zero is if either of these are involved
 			diff |= LD_CLLCOUNT;
 
-		if (li->sidenum[0] != 0xffff)
+		if (li->sidenum[0] != NO_INDEX)
 		{
 			si = &sides[li->sidenum[0]];
 			spawnsi = &spawnsides[li->sidenum[0]];
@@ -706,7 +706,8 @@ static void ArchiveLines(savebuffer_t *save)
 			if (si->midtexture != spawnsi->midtexture)
 				diff |= LD_S1MIDTEX;
 		}
-		if (li->sidenum[1] != 0xffff)
+
+		if (li->sidenum[1] != NO_INDEX)
 		{
 			si = &sides[li->sidenum[1]];
 			spawnsi = &spawnsides[li->sidenum[1]];
@@ -786,6 +787,7 @@ static void UnArchiveFFloors(savebuffer_t *save, const sector_t *ss)
 		I_Error("Sector does not have any ffloors!");
 
 	fflr_i = READUINT16(save->p); // get first modified ffloor's number ready
+
 	for (;;) // for some reason the usual for (rover = x; ...) thing doesn't work here?
 	{
 		if (fflr_i == 0xffff) // end of modified ffloors list, let's stop already
@@ -3510,7 +3512,7 @@ static void P_ReloadSaveLevelData(void)
 		li->firsttag = spawnli->firsttag;
 		li->nexttag  = spawnli->nexttag;
 
-		if (li->sidenum[0] != 0xffff)
+		if (li->sidenum[0] != NO_INDEX)
 		{
 			si = &sides[li->sidenum[0]];
 			spawnsi = &spawnsides[li->sidenum[0]];
@@ -3521,7 +3523,7 @@ static void P_ReloadSaveLevelData(void)
 			si->midtexture = spawnsi->midtexture;
 		}
 
-		if (li->sidenum[1] != 0xffff)
+		if (li->sidenum[1] != NO_INDEX)
 		{
 			si = &sides[li->sidenum[1]];
 			spawnsi = &spawnsides[li->sidenum[1]];
@@ -3588,8 +3590,11 @@ FUNCINLINE static ATTRINLINE boolean P_NetUnArchiveMisc(savebuffer_t *save, bool
 		if (!P_SetupLevel(true, reloading))
 		{
 			CONS_Alert(CONS_ERROR, M_GetText("Can't load the level!\n"));
+			P_FreeCorruptMapWarnings();
 			return false;
 		}
+
+		P_PrintCorruptMapWarnings();
 	}
 	else
 	{

src/p_setup.c

@@ -188,6 +188,57 @@ FUNCNORETURN static ATTRNORETURN void CorruptMapError(const char *msg)
 	I_Error("Invalid or corrupt map.\nLook in log file or text console for technical details.");
 }
 
+static char **mapwarnings = NULL;
+static size_t nummapwarnings = 0;
+
+// collect map errors we can fix clientside
+// we then can print em when the map finishes loading
+// so they actually appear and raise awareness shits fucked
+// see G_DoLoadLevel as to why :chaosleep:
+static void CorruptMapWarning(const char *msg)
+{
+#ifdef PARANOIA
+	// just error out
+	I_Error("%sThis WILL crash Vanilla clients!\n", msg);
+#endif
+	nummapwarnings++;
+	mapwarnings = Z_Realloc(mapwarnings, nummapwarnings * sizeof(*mapwarnings), PU_STATIC, NULL);
+	mapwarnings[nummapwarnings-1] = Z_StrDup(msg);
+}
+
+void P_PrintCorruptMapWarnings(void)
+{
+	size_t i;
+
+	if (!nummapwarnings)
+		return;
+
+	for (i = 0; i < nummapwarnings; i++)
+	{
+		CONS_Alert(CONS_ERROR, "%sAttempting to fix... This WILL crash Vanilla clients!\n", mapwarnings[i]);
+	}
+
+	P_FreeCorruptMapWarnings();
+}
+
+void P_FreeCorruptMapWarnings(void)
+{
+	size_t i;
+
+	if (!nummapwarnings)
+		return;
+
+	for (i = 0; i < nummapwarnings; i++)
+	{
+		Z_Free(mapwarnings[i]);
+		mapwarnings[i] = NULL;
+	}
+
+	Z_Free(mapwarnings);
+	mapwarnings = NULL;
+	nummapwarnings = 0;
+}
+
 #define NUMLAPS_DEFAULT 3
 
 static void P_ClearMapHeaderLighting(mapheader_lighting_t *lighting)
@@ -437,8 +488,39 @@ static void P_LoadSegs(UINT8 *data)
 
 	for (i = 0; i < numsegs; i++, li++, ml++)
 	{
-		li->v1 = &vertexes[SHORT(ml->v1)];
-		li->v2 = &vertexes[SHORT(ml->v2)];
+		INT16 v1, v2;
+
+		v1 = SHORT(ml->v1);
+		v2 = SHORT(ml->v2);
+
+		// e6y
+		// check and fix wrong references to non-existent vertexes
+		// see e1m9 @ NIVELES.WAD
+		// http://www.doomworld.com/idgames/index.php?id=12647
+		if ((unsigned)v1 >= numvertexes || (unsigned)v2 >= numvertexes)
+		{
+			if ((unsigned)v1 >= numvertexes)
+				CorruptMapWarning(va("P_LoadSegs: seg %s references a non-existent vertex %d\n", sizeu1(i), v1));
+			if ((unsigned)v2 >= numvertexes)
+				CorruptMapWarning(va("P_LoadSegs: seg %s references a non-existent vertex %d\n", sizeu1(i), v2));
+
+			if (li->sidedef == &sides[li->linedef->sidenum[0]])
+			{
+				li->v1 = lines[ml->linedef].v1;
+				li->v2 = lines[ml->linedef].v2;
+			}
+			else
+			{
+				li->v1 = lines[ml->linedef].v2;
+				li->v2 = lines[ml->linedef].v1;
+			}
+		}
+		else
+		{
+			li->v1 = &vertexes[v1];
+			li->v2 = &vertexes[v2];
+		}
+
 #ifdef HWRENDER
 		if (rendermode == render_opengl)
 		{
@@ -455,14 +537,59 @@ static void P_LoadSegs(UINT8 *data)
 		li->angle = (SHORT(ml->angle))<<FRACBITS;
 		li->offset = (SHORT(ml->offset))<<FRACBITS;
 		rawlinedef = SHORT(ml->linedef);
+
+		//e6y: check for wrong indexes
+		if ((unsigned)rawlinedef >= numlines)
+		{
+			I_Error("P_LoadSegs: seg %s references a non-existent linedef %d", sizeu1(i), (unsigned)rawlinedef);
+		}
+
 		ldef = &lines[rawlinedef];
 		li->linedef = ldef;
-		li->side = rawside = SHORT(ml->side);
+		rawside = SHORT(ml->side);
+
+		//e6y: fix wrong side index
+		if (rawside != 0 && rawside != 1)
+		{
+			CorruptMapWarning(va("P_LoadSegs: seg %s contains wrong side index %d.\n", sizeu1(i), rawside));
+			rawside = 1;
+		}
+
+		//e6y: check for wrong indexes
+		if (ldef->sidenum[rawside] >= numsides)
+		{
+			I_Error("P_LoadSegs: linedef %d for seg %s references a non-existent sidedef %d", rawlinedef, sizeu1(i), ldef->sidenum[rawside]);
+		}
+
+		li->side = rawside;
+
 		li->sidedef = &sides[ldef->sidenum[rawside]];
-		li->frontsector = sides[ldef->sidenum[rawside]].sector;
+
+		/* cph 2006/09/30 - our frontsector can be the second side of the
+		 * linedef, so must check for NO_INDEX in case we are incorrectly
+		 * referencing the back of a 1S line */
+		if (ldef->sidenum[rawside] == NO_INDEX)
+		{
+			CorruptMapWarning(va("P_LoadSegs: front of seg %s has no sidedef\n", sizeu1(i)));
+			li->frontsector = NULL;
+		}
+		else
+		{
+			li->frontsector = sides[ldef->sidenum[rawside]].sector;
+		}
 
 		if (ldef->flags & ML_TWOSIDED)
-			li->backsector = sides[ldef->sidenum[rawside^1]].sector;
+		{
+			if (ldef->sidenum[rawside^1] == NO_INDEX)
+			{
+				CorruptMapWarning(va("P_LoadSegs: back of seg %s has no sidedef while being marked as double sided\n", sizeu1(i)));
+				li->backsector = NULL;
+			}
+			else
+			{
+				li->backsector = sides[ldef->sidenum[rawside^1]].sector;
+			}
+		}
 
 		P_UpdateSegLightOffset(li);
 	}
@@ -738,7 +865,33 @@ static void P_LoadNodes(UINT8 *data)
 
 		for (j = 0; j < 2; j++)
 		{
-			no->children[j] = SHORT(mn->children[j]);
+			UINT16 child;
+
+			child = SHORT(mn->children[j]);
+
+			if (child & NF_SUBSECTOR)
+			{
+				// Convert to extended type
+				child &= ~NF_SUBSECTOR;
+
+				// haleyjd 11/06/10: check for invalid subsector reference
+				if (child >= numsubsectors)
+				{
+					CorruptMapWarning(va("P_LoadNodes: BSP tree %s references invalid subsector %d\n", sizeu1(i), child));
+					child = 0;
+				}
+
+				child |= NF_SUBSECTOR;
+			}
+			else if (child >= numnodes)
+			{
+				CorruptMapWarning(va("P_LoadNodes: BSP node %s references invalid node.\n", sizeu1(i)));
+				//I_Error("P_LoadNodes: BSP node %d references invalid node %d.\n", sizeu1(i), Index(((node_t *)no->children[j])));
+				child = 0;
+			}
+
+			no->children[j] = child;
+
 			for (k = 0; k < 4; k++)
 				no->bbox[j][k] = SHORT(mn->bbox[j][k])<<FRACBITS;
 		}
@@ -1001,9 +1154,9 @@ static void P_InitializeLinedef(line_t *ld)
 	// cph 2002/07/20 - these errors are fatal if not fixed, so apply them
 	for (j = 0; j < 2; j++)
 	{
-		if (ld->sidenum[j] != 0xffff && ld->sidenum[j] >= (UINT16)numsides)
+		if (ld->sidenum[j] != NO_INDEX && ld->sidenum[j] >= (UINT16)numsides)
 		{
-			ld->sidenum[j] = 0xffff;
+			ld->sidenum[j] = NO_INDEX;
 			CONS_Debug(DBG_SETUP, "P_InitializeLinedef: Linedef %s has out-of-range sidedef number\n", sizeu1((size_t)(ld - lines)));
 		}
 	}
@@ -1011,23 +1164,23 @@ static void P_InitializeLinedef(line_t *ld)
 	ld->firsttag = ld->nexttag = -1;
 
 	// killough 11/98: fix common wad errors (missing sidedefs):
-	if (ld->sidenum[0] == 0xffff)
+	if (ld->sidenum[0] == NO_INDEX)
 	{
 		ld->sidenum[0] = 0;  // Substitute dummy sidedef for missing right side
 		// cph - print a warning about the bug
 		CONS_Debug(DBG_SETUP, "P_InitializeLinedef: Linedef %s missing first sidedef\n", sizeu1((size_t)(ld - lines)));
 	}
 
-	if ((ld->sidenum[1] == 0xffff) && (ld->flags & ML_TWOSIDED))
+	if ((ld->sidenum[1] == NO_INDEX) && (ld->flags & ML_TWOSIDED))
 	{
 		ld->flags &= ~ML_TWOSIDED;  // Clear 2s flag for missing left side
 		// cph - print a warning about the bug
 		CONS_Debug(DBG_SETUP, "P_InitializeLinedef: Linedef %s has two-sided flag set, but no second sidedef\n", sizeu1((size_t)(ld - lines)));
 	}
 
-	if (ld->sidenum[0] != 0xffff && ld->special)
+	if (ld->sidenum[0] != NO_INDEX && ld->special)
 		sides[ld->sidenum[0]].special = ld->special;
-	if (ld->sidenum[1] != 0xffff && ld->special)
+	if (ld->sidenum[1] != NO_INDEX && ld->special)
 		sides[ld->sidenum[1]].special = ld->special;
 }
 
@@ -1060,10 +1213,10 @@ static void P_LoadLineDefs2(void)
 	for (; i--; ld++)
 	{
 		ld->frontsector = sides[ld->sidenum[0]].sector; //e6y: Can't be -1 here
-		ld->backsector  = ld->sidenum[1] != 0xffff ? sides[ld->sidenum[1]].sector : NULL;
+		ld->backsector  = ld->sidenum[1] != NO_INDEX ? sides[ld->sidenum[1]].sector : NULL;
 
 		// Repeat count for midtexture
-		if ((ld->flags & ML_EFFECT5) && (ld->sidenum[1] != 0xffff))
+		if ((ld->flags & ML_EFFECT5) && (ld->sidenum[1] != NO_INDEX))
 		{
 			sides[ld->sidenum[0]].repeatcnt = (INT16)(((unsigned)sides[ld->sidenum[0]].textureoffset >> FRACBITS) >> 12);
 			sides[ld->sidenum[0]].textureoffset = (((unsigned)sides[ld->sidenum[0]].textureoffset >> FRACBITS) & 2047) << FRACBITS;
@@ -1079,13 +1232,13 @@ static void P_LoadLineDefs2(void)
 				{
 					size_t len = strlen(sides[ld->sidenum[0]].text)+1;
 
-					if (ld->sidenum[1] != 0xffff && sides[ld->sidenum[1]].text)
+					if (ld->sidenum[1] != NO_INDEX && sides[ld->sidenum[1]].text)
 						len += strlen(sides[ld->sidenum[1]].text);
 
 					ld->text = Z_Malloc(len, PU_LEVEL, NULL);
 					memcpy(ld->text, sides[ld->sidenum[0]].text, strlen(sides[ld->sidenum[0]].text)+1);
 
-					if (ld->sidenum[1] != 0xffff && sides[ld->sidenum[1]].text)
+					if (ld->sidenum[1] != NO_INDEX && sides[ld->sidenum[1]].text)
 						memcpy(ld->text+strlen(ld->text)+1, sides[ld->sidenum[1]].text, strlen(sides[ld->sidenum[1]].text)+1);
 				}
 				break;
@@ -1747,16 +1900,11 @@ static boolean P_LoadRawBlockMap(UINT8 *data, size_t count)
 	// http://www.doomworld.com/idgames/index.php?id=12935
 	if (!P_VerifyBlockMap(count))
 	{
-#ifdef PARANOIA
-		I_Error("P_LoadBlockMap: erroneous BLOCKMAP lump may cause crashes.\n");
-#endif
-		CONS_Alert(CONS_ERROR, "P_LoadBlockMap: erroneous BLOCKMAP lump may cause crashes.\n");
-
-		//Z_Free(blockmaplump);
-		//blockmaplump = NULL;
-		//return false; // ideally we would just let the game rebuild the blockmap
-						// but this has a chance of desynching vanilla clients
-						// not sure whats worse honestly and i do not want to decide that :chaosleep:
+		CorruptMapWarning(va("P_LoadBlockMap: corrupted or invalid BLOCKMAP lump! Check the log for more information.\n"));
+		// vanilla WILL crash here anyways so just rebuild it ourselves
+		Z_Free(blockmaplump);
+		blockmaplump = NULL;
+		return false;
 	}
 
 	// clear out mobj chains
@@ -1793,22 +1941,35 @@ static void P_GroupLines(void)
 	for (i = 0; i < numsubsectors; i++, ss++)
 	{
 		if (ss->firstline >= numsegs)
+		{
 			CorruptMapError(va("P_GroupLines: ss->firstline invalid "
 				"(subsector %s, firstline refers to %d of %s)", sizeu1(i), ss->firstline,
 				sizeu2(numsegs)));
+		}
+
 		seg = &segs[ss->firstline];
 		sidei = (size_t)(seg->sidedef - sides);
+
 		if (!seg->sidedef)
+		{
 			CorruptMapError(va("P_GroupLines: seg->sidedef is NULL "
 				"(subsector %s, firstline is %d)", sizeu1(i), ss->firstline));
+		}
+
 		if (seg->sidedef - sides < 0 || seg->sidedef - sides > (UINT16)numsides)
+		{
 			CorruptMapError(va("P_GroupLines: seg->sidedef refers to sidedef %s of %s "
 				"(subsector %s, firstline is %d)", sizeu1(sidei), sizeu2(numsides),
 				sizeu3(i), ss->firstline));
+		}
+
 		if (!seg->sidedef->sector)
+		{
 			CorruptMapError(va("P_GroupLines: seg->sidedef->sector is NULL "
 				"(subsector %s, firstline is %d, sidedef is %s)", sizeu1(i), ss->firstline,
 				sizeu1(sidei)));
+		}
+
 		ss->sector = seg->sidedef->sector;
 	}
 
@@ -1886,11 +2047,16 @@ static void P_LoadReject(UINT8 *data, size_t rejectsize)
 	{
 		if (rejectsize < neededsize)
 		{
-#ifdef PARANOIA
-			I_Error("REJECT is %s byte%s too small. REJECT might be invalid and crash vanilla clients!\n", sizeu1(neededsize - rejectsize), (neededsize - rejectsize) == 1 ? "" : "s");
-#endif
-			CONS_Alert(CONS_ERROR, "REJECT is %s byte%s too small. REJECT might be invalid and crash vanilla clients!\n", sizeu1(neededsize - rejectsize), (neededsize - rejectsize) == 1 ? "" : "s");
+			CorruptMapWarning(va("P_LoadReject: REJECT is %s byte%s too small. REJECT might be invalid!\n", sizeu1(neededsize - rejectsize), (neededsize - rejectsize) == 1 ? "" : "s"));
+#ifdef COMPAT_VANILLA
+			// we can pad this and somewhat prevent desyncs
+			// probs not cool if the reject is from a completely different map
+			// but whatever
 			allocsize = neededsize;
+#else
+			rejectmatrix = NULL;
+			return;
+#endif
 		}
 
 		rejectmatrix = Z_Calloc(allocsize, PU_LEVEL, NULL); // allocate memory for the reject matrix

src/p_setup.h

@@ -114,6 +114,9 @@ size_t P_PrecacheLevelFlats(void);
 
 void P_AllocMapHeader(INT16 i);
 
+void P_PrintCorruptMapWarnings(void);
+void P_FreeCorruptMapWarnings(void);
+
 #ifdef __cplusplus
 } // extern "C"
 #endif

src/p_spec.c

@@ -889,7 +889,7 @@ static boolean PolyDoor(line_t *line)
 			pdd.angle    = line->angle; // angle of motion
 			pdd.distance = sides[line->sidenum[0]].rowoffset;
 
-			if (line->sidenum[1] != 0xffff)
+			if (line->sidenum[1] != NO_INDEX)
 				pdd.delay = sides[line->sidenum[1]].textureoffset >> FRACBITS; // delay in tics
 			else
 				pdd.delay = 0;
@@ -899,7 +899,7 @@ static boolean PolyDoor(line_t *line)
 			pdd.speed    = sides[line->sidenum[0]].textureoffset >> FRACBITS; // angular speed
 			pdd.distance = sides[line->sidenum[0]].rowoffset >> FRACBITS; // angular distance
 
-			if (line->sidenum[1] != 0xffff)
+			if (line->sidenum[1] != NO_INDEX)
 				pdd.delay = sides[line->sidenum[1]].textureoffset >> FRACBITS; // delay in tics
 			else
 				pdd.delay = 0;
@@ -1989,8 +1989,8 @@ static void P_ProcessLineSpecial(line_t *line, mobj_t *mo, sector_t *callsec)
 				INT32 position = (INT32)max(sides[line->sidenum[0]].midtexture, 0);
 				UINT32 prefadems = (UINT32)max(sides[line->sidenum[0]].textureoffset >> FRACBITS, 0);
 				UINT32 postfadems = (UINT32)max(sides[line->sidenum[0]].rowoffset >> FRACBITS, 0);
-				UINT8 fadetarget = (UINT8)max((line->sidenum[1] != 0xffff) ? sides[line->sidenum[1]].textureoffset >> FRACBITS : 0, 0);
-				INT16 fadesource = (INT16)max((line->sidenum[1] != 0xffff) ? sides[line->sidenum[1]].rowoffset >> FRACBITS : -1, -1);
+				UINT8 fadetarget = (UINT8)max((line->sidenum[1] != NO_INDEX) ? sides[line->sidenum[1]].textureoffset >> FRACBITS : 0, 0);
+				INT16 fadesource = (INT16)max((line->sidenum[1] != NO_INDEX) ? sides[line->sidenum[1]].rowoffset >> FRACBITS : -1, -1);
 
 				// Seek offset from current song position
 				if (line->flags & ML_EFFECT1)
@@ -2504,7 +2504,7 @@ static void P_ProcessLineSpecial(line_t *line, mobj_t *mo, sector_t *callsec)
 
 				var1 = sides[line->sidenum[0]].toptexture; //(line->dx>>FRACBITS)-1;
 
-				if (line->sidenum[1] != 0xffff && line->flags & ML_BLOCKMONSTERS) // read power from back sidedef
+				if (line->sidenum[1] != NO_INDEX && line->flags & ML_BLOCKMONSTERS) // read power from back sidedef
 					var2 = sides[line->sidenum[1]].toptexture;
 				else if (line->flags & ML_NOCLIMB) // 'Infinite'
 					var2 = UINT16_MAX;
@@ -2633,7 +2633,7 @@ static void P_ProcessLineSpecial(line_t *line, mobj_t *mo, sector_t *callsec)
 					if (always || this->bottomtexture)
 						this->bottomtexture = set->bottomtexture;
 
-					if (lines[linenum].sidenum[1] == 0xffff)
+					if (lines[linenum].sidenum[1] == NO_INDEX)
 						continue; // One-sided stops here.
 
 					// Back side
@@ -2682,7 +2682,7 @@ static void P_ProcessLineSpecial(line_t *line, mobj_t *mo, sector_t *callsec)
 			sector_t *sec;
 			mobj_t *thing;
 
-			if (line->sidenum[1] != 0xffff)
+			if (line->sidenum[1] != NO_INDEX)
 				state = (statenum_t)sides[line->sidenum[1]].toptexture;
 
 			while ((secnum = P_FindSectorFromLineTag(line, secnum)) >= 0)
@@ -4609,11 +4609,13 @@ void P_UpdateSpecials(void)
 	// POINT LIMIT
 	P_CheckPointLimit();
 
+#ifdef COMPAT_VANILLA
 	// Dynamic slopeness
 	// we run this here only when not joined midrace
 	// for vanilla compat reasons :chaosleep:
 	if (!midgamejoin)
 		P_RunDynamicSlopes();
+#endif
 
 	P_UpdateAnimFlats();
 }
@@ -6056,7 +6058,7 @@ void P_SpawnSpecials(INT32 fromnetsave, boolean reloadinggamestate)
 				break;
 
 			case 259: // Make-Your-Own FOF!
-				if (lines[i].sidenum[1] != 0xffff)
+				if (lines[i].sidenum[1] != NO_INDEX)
 				{
 					UINT8 *data;
 					UINT16 b;
@@ -6785,7 +6787,7 @@ static void P_SpawnScrollers(void)
 			case 506:
 				s = lines[i].sidenum[1];
 
-				if (s != 0xffff)
+				if (s != NO_INDEX)
 					Add_Scroller(sc_side, -sides[s].textureoffset, sides[s].rowoffset, -1, lines[i].sidenum[0], accel, 0);
 				else
 					CONS_Debug(DBG_GAMELOGIC, "Line special 506 (line #%s) missing 2nd side!\n", sizeu1(i));

src/p_tick.c

@@ -646,7 +646,9 @@ void P_Ticker(boolean run)
 	if (run)
 	{
 		// Dynamic slopeness
+#ifdef COMPAT_VANILLA
 		if (midgamejoin) // only run here if we joined midgame to fix some desynchs
+#endif
 			P_RunDynamicSlopes();
 
 		PS_START_TIMING(ps_thinkertime);

src/r_defs.h

@@ -430,7 +430,7 @@ typedef struct line_s
 	INT16 tag;
 
 	// Visual appearance: sidedefs.
-	UINT16 sidenum[2]; // sidenum[1] will be 0xffff if one-sided
+	UINT16 sidenum[2]; // sidenum[1] will be NO_INDEX if one-sided
 	fixed_t alpha; // translucency
 	UINT8 blendmode; // blendmode
 

src/r_segs.cpp

@@ -2204,7 +2204,7 @@ void R_StoreWallRange(INT32 start, INT32 stop)
 			topremap = (encoremap && !(curline->linedef->flags & ML_TFERLINE));
 
 			if ((linedef->flags & (ML_DONTPEGTOP) && (linedef->flags & ML_DONTPEGBOTTOM))
-				&& linedef->sidenum[1] != 0xffff)
+				&& linedef->sidenum[1] != NO_INDEX)
 			{
 				// Special case... use offsets from 2nd side but only if it has a texture.
 				side_t *def = &sides[linedef->sidenum[1]];

src/r_splats.c

@@ -131,7 +131,7 @@ void R_AddWallSplat(line_t *wallline, INT16 sectorside, const char *patchname, f
 	// set the splat
 	splat->patch = W_GetNumForName(patchname);
 	sectorside ^= 1;
-	if (wallline->sidenum[sectorside] != 0xffff)
+	if (wallline->sidenum[sectorside] != NO_INDEX)
 	{
 		backsector = sides[wallline->sidenum[sectorside]].sector;