Changes:

- Implemented Lua support for side overlays
- OpenGL: Fixed rendering of overlays in one-sided walls
- Made edge flags into its own enumeration

src/hardware/hw_main.c

@@ -1244,7 +1244,7 @@ static void HWR_GetExtraTextureCoords(unsigned which, fixed_t *top, fixed_t *bot
 
 	fixed_t rowoffset = FixedDiv(gl_sidedef->rowoffset + gl_sidedef->overlays[which].offsety, abs(gl_sidedef->overlays[which].scaley));
 
-	if (gl_sidedef->flags & GET_SIDEFLAG_EDGENOSKEW(which))
+	if (gl_sidedef->overlays[which].flags & SIDEOVERLAYFLAG_NOSKEW)
 	{
 		if (IS_TOP_EDGE_TEXTURE(which))
 		{
@@ -1357,12 +1357,13 @@ static void HWR_DoExtraTextureCut(UINT8 intersected, UINT8 which, v2d_t vs, v2d_
 	*worldbottom      = P_GetSectorFloorZAt(gl_frontsector, v1x, v1y);
 	*worldbottomslope = P_GetSectorFloorZAt(gl_frontsector, v2x, v2y);
 
-	sector_t *back = gl_backsector ? gl_backsector : gl_frontsector;
-
-	*worldhigh        = P_GetSectorCeilingZAt(back, v1x, v1y);
-	*worldhighslope   = P_GetSectorCeilingZAt(back, v2x, v2y);
-	*worldlow         = P_GetSectorFloorZAt(back, v1x, v1y);
-	*worldlowslope    = P_GetSectorFloorZAt(back, v2x, v2y);
+	if (gl_backsector)
+	{
+		*worldhigh        = P_GetSectorCeilingZAt(gl_backsector, v1x, v1y);
+		*worldhighslope   = P_GetSectorCeilingZAt(gl_backsector, v2x, v2y);
+		*worldlow         = P_GetSectorFloorZAt(gl_backsector, v1x, v1y);
+		*worldlowslope    = P_GetSectorFloorZAt(gl_backsector, v2x, v2y);
+	}
 
 	HWR_GetExtraTextureCoords(which, polytop, polybottom, polytopslope, polybottomslope, *worldtop, *worldbottom, *worldhigh, *worldlow, *worldtopslope, *worldbottomslope, *worldhighslope, *worldlowslope, midtexheight);
 }
@@ -1385,10 +1386,12 @@ static void HWR_SetWallEndCoordsOffset(FOutVector wallVerts[4], float wallx2, fl
 	wallVerts[2].z = wallVerts[1].z = wally2;
 }
 
-// Draws an extra texture (sorry for the length)
+// Draws an extra texture
 static void HWR_RenderExtraTexture(unsigned which, v2d_t vs, v2d_t ve, float xcliplow, float xcliphigh, UINT32 lightnum)
 {
-	INT32 texnum = R_GetTextureNum(gl_sidedef->overlays[which].texture);
+	side_overlay_t *overlay = &gl_sidedef->overlays[which];
+
+	INT32 texnum = R_GetTextureNum(overlay->texture);
 	if (texnum <= 0 || texnum >= numtextures)
 		return;
 
@@ -1402,23 +1405,18 @@ static void HWR_RenderExtraTexture(unsigned which, v2d_t vs, v2d_t ve, float xcl
 
 	float flength = gl_curline->flength;
 
-	sector_t *back = gl_backsector ? gl_backsector : gl_frontsector;
-
 	fixed_t worldtop         = P_GetSectorCeilingZAt(gl_frontsector, v1x, v1y);
 	fixed_t worldtopslope    = P_GetSectorCeilingZAt(gl_frontsector, v2x, v2y);
 	fixed_t worldbottom      = P_GetSectorFloorZAt(gl_frontsector, v1x, v1y);
 	fixed_t worldbottomslope = P_GetSectorFloorZAt(gl_frontsector, v2x, v2y);
 
-	fixed_t worldhigh        = P_GetSectorCeilingZAt(back, v1x, v1y);
-	fixed_t worldhighslope   = P_GetSectorCeilingZAt(back, v2x, v2y);
-	fixed_t worldlow         = P_GetSectorFloorZAt(back, v1x, v1y);
-	fixed_t worldlowslope    = P_GetSectorFloorZAt(back, v2x, v2y);
+	fixed_t worldhigh = 0, worldhighslope = 0, worldlow = 0, worldlowslope = 0;
 
-	fixed_t texheight = FixedDiv(textureheight[texnum], abs(gl_sidedef->overlays[which].scaley));
+	fixed_t texheight = FixedDiv(textureheight[texnum], abs(overlay->scaley));
 
 	INT32 repeats;
 
-	if (gl_sidedef->flags & GET_SIDEFLAG_EDGEWRAP(which))
+	if (overlay->flags & SIDEOVERLAYFLAG_WRAP)
 	{
 		fixed_t high, low;
 
@@ -1467,8 +1465,8 @@ static void HWR_RenderExtraTexture(unsigned which, v2d_t vs, v2d_t ve, float xcl
 		repeats = 1;
 
 	GLMapTexture_t *grTex = HWR_GetTexture(texnum);
-	float xscale = FixedToFloat(gl_sidedef->overlays[which].scalex);
-	float yscale = FixedToFloat(gl_sidedef->overlays[which].scaley);
+	float xscale = FixedToFloat(overlay->scalex);
+	float yscale = FixedToFloat(overlay->scaley);
 
 	float xcliplowbase = xcliplow;
 	float xclipoffset = 0.0f;
@@ -1479,25 +1477,43 @@ static void HWR_RenderExtraTexture(unsigned which, v2d_t vs, v2d_t ve, float xcl
 	// Find the wall's coordinates
 	fixed_t midtexheight = texheight * repeats;
 
+	if (gl_backsector)
+	{
+		worldhigh        = P_GetSectorCeilingZAt(gl_backsector, v1x, v1y);
+		worldhighslope   = P_GetSectorCeilingZAt(gl_backsector, v2x, v2y);
+		worldlow         = P_GetSectorFloorZAt(gl_backsector, v1x, v1y);
+		worldlowslope    = P_GetSectorFloorZAt(gl_backsector, v2x, v2y);
+	}
+
 	HWR_GetExtraTextureCoords(which, &polytop, &polybottom, &polytopslope, &polybottomslope, worldtop, worldbottom, worldhigh, worldlow, worldtopslope, worldbottomslope, worldhighslope, worldlowslope, midtexheight);
 
 	// Find where to cut it
 	fixed_t lowcut, highcut;
 	fixed_t lowcutslope, highcutslope;
 
-	if (IS_TOP_EDGE_TEXTURE(which))
+	if (!gl_backsector)
 	{
-		lowcut = worldhigh;
+		lowcut = worldbottom;
 		highcut = worldtop;
-		lowcutslope = worldhighslope;
+		lowcutslope = worldbottomslope;
 		highcutslope = worldtopslope;
 	}
 	else
 	{
-		lowcut = worldbottom;
-		highcut = worldlow;
-		lowcutslope = worldbottomslope;
-		highcutslope = worldlowslope;
+		if (IS_TOP_EDGE_TEXTURE(which))
+		{
+			lowcut = worldhigh;
+			highcut = worldtop;
+			lowcutslope = worldhighslope;
+			highcutslope = worldtopslope;
+		}
+		else
+		{
+			lowcut = worldbottom;
+			highcut = worldlow;
+			lowcutslope = worldbottomslope;
+			highcutslope = worldlowslope;
+		}
 	}
 
 	// Time to render the wall (or so you thought)
@@ -1605,19 +1621,29 @@ static void HWR_RenderExtraTexture(unsigned which, v2d_t vs, v2d_t ve, float xcl
 
 			HWR_GetExtraTextureCoords(which, &polytop, &polybottom, &polytopslope, &polybottomslope, worldtop, worldbottom, worldhigh, worldlow, worldtopslope, worldbottomslope, worldhighslope, worldlowslope, midtexheight);
 
-			if (IS_TOP_EDGE_TEXTURE(which))
+			if (!gl_backsector)
 			{
-				lowcut = worldhigh;
+				lowcut = worldbottom;
 				highcut = worldtop;
-				lowcutslope = worldhighslope;
+				lowcutslope = worldbottomslope;
 				highcutslope = worldtopslope;
 			}
 			else
 			{
-				lowcut = worldbottom;
-				highcut = worldlow;
-				lowcutslope = worldbottomslope;
-				highcutslope = worldlowslope;
+				if (IS_TOP_EDGE_TEXTURE(which))
+				{
+					lowcut = worldhigh;
+					highcut = worldtop;
+					lowcutslope = worldhighslope;
+					highcutslope = worldtopslope;
+				}
+				else
+				{
+					lowcut = worldbottom;
+					highcut = worldlow;
+					lowcutslope = worldbottomslope;
+					highcutslope = worldlowslope;
+				}
 			}
 
 			h = polytop;
@@ -1773,12 +1799,12 @@ static void HWR_RenderExtraTexture(unsigned which, v2d_t vs, v2d_t ve, float xcl
 	// Left side
 	wallVerts[3].t = texturevpeg * yscale * grTex->scaleY;
 	wallVerts[0].t = (h - l + texturevpeg) * yscale * grTex->scaleY;
-	wallVerts[0].s = wallVerts[3].s = ((xcliplow * xscale) + gl_sidedef->overlays[which].offsetx) * grTex->scaleX;
+	wallVerts[0].s = wallVerts[3].s = ((xcliplow * xscale) + overlay->offsetx) * grTex->scaleX;
 
 	// Right side
 	wallVerts[2].t = texturevpegslope * yscale * grTex->scaleY;
 	wallVerts[1].t = (hS - lS + texturevpegslope) * yscale * grTex->scaleY;
-	wallVerts[2].s = wallVerts[1].s = ((xcliphigh * xscale) + gl_sidedef->overlays[which].offsetx) * grTex->scaleX;
+	wallVerts[2].s = wallVerts[1].s = ((xcliphigh * xscale) + overlay->offsetx) * grTex->scaleX;
 
 	// set top/bottom coords
 	// Take the texture peg into account, rather than changing the offsets past
@@ -1831,10 +1857,13 @@ static void HWR_RenderExtraTexture(unsigned which, v2d_t vs, v2d_t ve, float xcl
 	worldbottom      = P_GetSectorFloorZAt(gl_frontsector, v1x, v1y);
 	worldbottomslope = P_GetSectorFloorZAt(gl_frontsector, v2x, v2y);
 
-	worldhigh        = P_GetSectorCeilingZAt(back, v1x, v1y);
-	worldhighslope   = P_GetSectorCeilingZAt(back, v2x, v2y);
-	worldlow         = P_GetSectorFloorZAt(back, v1x, v1y);
-	worldlowslope    = P_GetSectorFloorZAt(back, v2x, v2y);
+	if (gl_backsector)
+	{
+		worldhigh        = P_GetSectorCeilingZAt(gl_backsector, v1x, v1y);
+		worldhighslope   = P_GetSectorCeilingZAt(gl_backsector, v2x, v2y);
+		worldlow         = P_GetSectorFloorZAt(gl_backsector, v1x, v1y);
+		worldlowslope    = P_GetSectorFloorZAt(gl_backsector, v2x, v2y);
+	}
 
 	HWR_GetExtraTextureCoords(which, &polytop, &polybottom, &polytopslope, &polybottomslope, worldtop, worldbottom, worldhigh, worldlow, worldtopslope, worldbottomslope, worldhighslope, worldlowslope, midtexheight);
 
@@ -1866,12 +1895,12 @@ static void HWR_RenderExtraTexture(unsigned which, v2d_t vs, v2d_t ve, float xcl
 	// Left side
 	wallVerts[3].t = texturevpeg * yscale * grTex->scaleY;
 	wallVerts[0].t = (h - l + texturevpeg) * yscale * grTex->scaleY;
-	wallVerts[0].s = wallVerts[3].s = ((xcliplow * xscale) + gl_sidedef->overlays[which].offsetx) * grTex->scaleX;
+	wallVerts[0].s = wallVerts[3].s = ((xcliplow * xscale) + overlay->offsetx) * grTex->scaleX;
 
 	// Right side
 	wallVerts[2].t = texturevpegslope * yscale * grTex->scaleY;
 	wallVerts[1].t = (hS - lS + texturevpegslope) * yscale * grTex->scaleY;
-	wallVerts[2].s = wallVerts[1].s = ((xcliphigh * xscale) + gl_sidedef->overlays[which].offsetx) * grTex->scaleX;
+	wallVerts[2].s = wallVerts[1].s = ((xcliphigh * xscale) + overlay->offsetx) * grTex->scaleX;
 
 	if (gl_frontsector->numlights)
 		HWR_SplitWall(gl_frontsector, wallVerts, texnum, &Surf, FOF_CUTLEVEL, NULL, blendmode);
@@ -2169,14 +2198,14 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 		if (gl_midtexture)
 			HWR_RenderMidtexture(gl_midtexture, cliplow, cliphigh, worldtop, worldbottom, worldhigh, worldlow, worldtopslope, worldbottomslope, worldhighslope, worldlowslope, lightnum, wallVerts);
 
-		// Render extra textures
-		for (unsigned i = 0; i < NUM_WALL_OVERLAYS; i++)
-			HWR_RenderExtraTexture(i, vs, ve, cliplow, cliphigh, lightnum);
-
-		// Sky culling
-		// No longer so much a mess as before!
 		if (!gl_curline->polyseg) // Don't do it for polyobjects
 		{
+			// Render extra textures
+			for (unsigned i = 0; i < NUM_WALL_OVERLAYS; i++)
+				HWR_RenderExtraTexture(i, vs, ve, cliplow, cliphigh, lightnum);
+
+			// Sky culling
+			// No longer so much a mess as before!
 			if (gl_frontsector->ceilingpic == skyflatnum
 				&& gl_backsector->ceilingpic != skyflatnum) // don't cull if back sector is also sky
 			{
@@ -2255,12 +2284,12 @@ static void HWR_ProcessSeg(void) // Sort of like GLWall::Process in GZDoom
 			}
 		}
 
-		// Render extra textures
-		for (unsigned i = 0; i < NUM_WALL_OVERLAYS; i++)
-			HWR_RenderExtraTexture(i, vs, ve, cliplow, cliphigh, lightnum);
-
 		if (!gl_curline->polyseg)
 		{
+			// Render extra textures
+			HWR_RenderExtraTexture(EDGE_TEXTURE_TOP_UPPER, vs, ve, cliplow, cliphigh, lightnum);
+			HWR_RenderExtraTexture(EDGE_TEXTURE_BOTTOM_LOWER, vs, ve, cliplow, cliphigh, lightnum);
+
 			if (gl_frontsector->ceilingpic == skyflatnum) // It's a single-sided line with sky for its sector
 			{
 				wallVerts[2].y = wallVerts[3].y = FIXED_TO_FLOAT(INT32_MAX); // draw to top of map space

src/lua_baselib.c

@@ -175,6 +175,7 @@ static const struct {
 	{META_VERTEX,       "vertex_t"},
 	{META_LINE,         "line_t"},
 	{META_SIDE,         "side_t"},
+	{META_SIDEOVERLAY,  "side_t.overlay"},
 	{META_SUBSECTOR,    "subsector_t"},
 	{META_SECTOR,       "sector_t"},
 	{META_FFLOOR,       "ffloor_t"},

src/lua_libs.h

@@ -55,6 +55,7 @@ extern boolean ignoregameinputs;
 #define META_SEG "SEG_T*"
 #define META_NODE "NODE_T*"
 #endif
+#define META_SIDEOVERLAY "SIDE_T*OVERLAY"
 #define META_SLOPE "PSLOPE_T*"
 #define META_VECTOR2 "VECTOR2_T"
 #define META_VECTOR3 "VECTOR3_T"

src/lua_maplib.c

@@ -209,6 +209,10 @@ enum side_e {
 	side_toptexture,
 	side_bottomtexture,
 	side_midtexture,
+	side_edge_top_upper,
+	side_edge_top_lower,
+	side_edge_bottom_upper,
+	side_edge_bottom_lower,
 	side_line,
 	side_sector,
 	side_special,
@@ -237,6 +241,10 @@ static const char *const side_opt[] = {
 	"toptexture",
 	"bottomtexture",
 	"midtexture",
+	"edge_top_upper",
+	"edge_top_lower",
+	"edge_bottom_upper",
+	"edge_bottom_lower",
 	"line",
 	"sector",
 	"special",
@@ -1297,6 +1305,22 @@ static int side_get(lua_State *L)
 	case side_midtexture:
 		lua_pushinteger(L, side->midtexture);
 		return 1;
+	case side_edge_top_upper:
+		LUA_PushUserdata(L, &side->overlays[EDGE_TEXTURE_TOP_UPPER], META_SIDEOVERLAY);
+		return 1;
+	case side_edge_top_lower:
+		if (side->line->backsector == NULL)
+			return 0;
+		LUA_PushUserdata(L, &side->overlays[EDGE_TEXTURE_TOP_LOWER], META_SIDEOVERLAY);
+		return 1;
+	case side_edge_bottom_upper:
+		if (side->line->backsector == NULL)
+			return 0;
+		LUA_PushUserdata(L, &side->overlays[EDGE_TEXTURE_BOTTOM_UPPER], META_SIDEOVERLAY);
+		return 1;
+	case side_edge_bottom_lower:
+		LUA_PushUserdata(L, &side->overlays[EDGE_TEXTURE_BOTTOM_LOWER], META_SIDEOVERLAY);
+		return 1;
 	case side_line:
 		LUA_PushUserdata(L, side->line, META_LINE);
 		return 1;
@@ -1352,6 +1376,10 @@ static int side_set(lua_State *L)
 	case side_sector:
 	case side_special:
 	case side_text:
+	case side_edge_top_upper:
+	case side_edge_top_lower:
+	case side_edge_bottom_upper:
+	case side_edge_bottom_lower:
 		return luaL_error(L, "side_t field " LUA_QS " cannot be set.", side_opt[field]);
 	default:
 		return luaL_error(L, "side_t has no field named " LUA_QS ".", lua_tostring(L, 2));
@@ -1422,6 +1450,129 @@ static int side_num(lua_State *L)
 	return 1;
 }
 
+////////////////////
+// side_overlay_t //
+////////////////////
+
+enum sideoverlay_e {
+	sideoverlay_valid = 0,
+	sideoverlay_texture,
+	sideoverlay_offsetx,
+	sideoverlay_offsety,
+	sideoverlay_scalex,
+	sideoverlay_scaley,
+	sideoverlay_noskew,
+	sideoverlay_wrap
+};
+
+static const char *const sideoverlay_opt[] = {
+	"valid",
+	"texture",
+	"offsetx",
+	"offsety",
+	"scalex",
+	"scaley",
+	"noskew",
+	"wrap",
+	NULL};
+
+static int sideoverlay_fields_ref = LUA_NOREF;
+
+static int sideoverlay_get(lua_State *L)
+{
+	side_overlay_t *overlay = *((side_overlay_t **)luaL_checkudata(L, 1, META_SIDEOVERLAY));
+	enum sideoverlay_e field = Lua_optoption(L, 2, sideoverlay_valid, sideoverlay_fields_ref);
+
+	if (!overlay)
+	{
+		if (field == sideoverlay_valid) {
+			lua_pushboolean(L, 0);
+			return 1;
+		}
+		return luaL_error(L, "accessed side_t.overlay doesn't exist anymore.");
+	}
+
+	switch(field)
+	{
+	case sideoverlay_valid:
+		lua_pushboolean(L, 1);
+		return 1;
+	case sideoverlay_texture:
+		lua_pushinteger(L, overlay->texture);
+		return 1;
+	case sideoverlay_offsetx:
+		lua_pushfixed(L, overlay->offsetx);
+		return 1;
+	case sideoverlay_offsety:
+		lua_pushfixed(L, overlay->offsety);
+		return 1;
+	case sideoverlay_scalex:
+		lua_pushfixed(L, overlay->scalex);
+		return 1;
+	case sideoverlay_scaley:
+		lua_pushfixed(L, overlay->scaley);
+		return 1;
+	case sideoverlay_noskew:
+		lua_pushboolean(L, overlay->flags & SIDEOVERLAYFLAG_NOSKEW);
+		return 1;
+	case sideoverlay_wrap:
+		lua_pushboolean(L, overlay->flags & SIDEOVERLAYFLAG_WRAP);
+		return 1;
+	}
+	return 0;
+}
+
+static int sideoverlay_set(lua_State *L)
+{
+	side_overlay_t *overlay = *((side_overlay_t **)luaL_checkudata(L, 1, META_SIDEOVERLAY));
+	enum sideoverlay_e field = Lua_optoption(L, 2, sideoverlay_valid, sideoverlay_fields_ref);
+
+	if (!overlay)
+	{
+		if (field == sideoverlay_valid) {
+			lua_pushboolean(L, 0);
+			return 1;
+		}
+		return luaL_error(L, "accessed side_t.overlay doesn't exist anymore.");
+	}
+
+	switch(field)
+	{
+	case side_valid:
+		return luaL_error(L, "side_t.overlay field " LUA_QS " cannot be set.", side_opt[field]);
+	default:
+		return luaL_error(L, "side_t.overlay has no field named " LUA_QS ".", lua_tostring(L, 2));
+	case sideoverlay_texture:
+		overlay->texture = luaL_checkinteger(L, 3);
+		break;
+	case sideoverlay_offsetx:
+		overlay->offsetx = luaL_checkfixed(L, 3);
+		break;
+	case sideoverlay_offsety:
+		overlay->offsety = luaL_checkfixed(L, 3);
+		break;
+	case sideoverlay_scalex:
+		overlay->scalex = luaL_checkfixed(L, 3);
+		break;
+	case sideoverlay_scaley:
+		overlay->scaley = luaL_checkfixed(L, 3);
+		break;
+	case sideoverlay_noskew:
+		if (luaL_checkboolean(L, 3))
+			overlay->flags |= SIDEOVERLAYFLAG_NOSKEW;
+		else
+			overlay->flags &= ~SIDEOVERLAYFLAG_NOSKEW;
+		break;
+	case sideoverlay_wrap:
+		if (luaL_checkboolean(L, 3))
+			overlay->flags |= SIDEOVERLAYFLAG_WRAP;
+		else
+			overlay->flags &= ~SIDEOVERLAYFLAG_WRAP;
+		break;
+	}
+	return 0;
+}
+
 //////////////
 // vertex_t //
 //////////////
@@ -2991,6 +3142,7 @@ int LUA_MapLib(lua_State *L)
 	LUA_RegisterUserdataMetatable(L, META_LINESTRINGARGS, linestringargs_get, NULL, linestringargs_len);
 	LUA_RegisterUserdataMetatable(L, META_SIDENUM, sidenum_get, NULL, NULL);
 	LUA_RegisterUserdataMetatable(L, META_SIDE, side_get, side_set, side_num);
+	LUA_RegisterUserdataMetatable(L, META_SIDEOVERLAY, sideoverlay_get, sideoverlay_set, NULL);
 	LUA_RegisterUserdataMetatable(L, META_VERTEX, vertex_get, NULL, vertex_num);
 	LUA_RegisterUserdataMetatable(L, META_FFLOOR, ffloor_get, ffloor_set, NULL);
 	LUA_RegisterUserdataMetatable(L, META_BBOX, bbox_get, NULL, NULL);
@@ -3003,6 +3155,7 @@ int LUA_MapLib(lua_State *L)
 	subsector_fields_ref = Lua_CreateFieldTable(L, subsector_opt);
 	line_fields_ref = Lua_CreateFieldTable(L, line_opt);
 	side_fields_ref = Lua_CreateFieldTable(L, side_opt);
+	sideoverlay_fields_ref = Lua_CreateFieldTable(L, sideoverlay_opt);
 	vertex_fields_ref = Lua_CreateFieldTable(L, vertex_opt);
 	ffloor_fields_ref = Lua_CreateFieldTable(L, ffloor_opt);
 	slope_fields_ref = Lua_CreateFieldTable(L, slope_opt);

src/lua_script.c

@@ -964,7 +964,11 @@ void LUA_InvalidateLevel(void)
 		LUA_InvalidateUserdata(lines[i].sidenum);
 	}
 	for (i = 0; i < numsides; i++)
+	{
+		for (unsigned j = 0; j < NUM_WALL_OVERLAYS; j++)
+			LUA_InvalidateUserdata(&sides[i].overlays[j]);
 		LUA_InvalidateUserdata(&sides[i]);
+	}
 	for (i = 0; i < numvertexes; i++)
 		LUA_InvalidateUserdata(&vertexes[i]);
 	for (i = 0; i < (size_t)numPolyObjects; i++)

src/p_setup.c

@@ -1366,13 +1366,12 @@ static void P_LoadSidedefs(UINT8 *data)
 		sd->scalex_top = sd->scalex_mid = sd->scalex_bottom = FRACUNIT;
 		sd->scaley_top = sd->scaley_mid = sd->scaley_bottom = FRACUNIT;
 
-		sd->flags = 0;
-
 		for (unsigned j = 0; j < NUM_WALL_OVERLAYS; j++)
 		{
 			sd->overlays[j].texture = R_TextureNumForName("-");
 			sd->overlays[j].offsetx = sd->overlays[j].offsety = 0;
 			sd->overlays[j].scalex = sd->overlays[j].scaley = FRACUNIT;
+			sd->overlays[j].flags = 0;
 		}
 
 		P_SetSidedefSector(i, (UINT16)SHORT(msd->sector));
@@ -1907,20 +1906,21 @@ static void ParseTextmapSectorParameter(UINT32 i, const char *param, const char
 
 static void ParseTextmapSidedefOverlay(unsigned which, UINT32 i, const char *param, const char *val)
 {
+	side_overlay_t *overlay = &sides[i].overlays[which];
 	if (fastcmp(param, "texture"))
-		sides[i].overlays[which].texture = R_TextureNumForName(val);
+		overlay->texture = R_TextureNumForName(val);
 	else if (fastcmp(param, "offsetx"))
-		sides[i].overlays[which].offsetx = FLOAT_TO_FIXED(atof(val));
+		overlay->offsetx = FLOAT_TO_FIXED(atof(val));
 	else if (fastcmp(param, "offsety"))
-		sides[i].overlays[which].offsety = FLOAT_TO_FIXED(atof(val));
+		overlay->offsety = FLOAT_TO_FIXED(atof(val));
 	else if (fastcmp(param, "scalex"))
-		sides[i].overlays[which].scalex = FLOAT_TO_FIXED(atof(val));
+		overlay->scalex = FLOAT_TO_FIXED(atof(val));
 	else if (fastcmp(param, "scaley"))
-		sides[i].overlays[which].scaley = FLOAT_TO_FIXED(atof(val));
+		overlay->scaley = FLOAT_TO_FIXED(atof(val));
 	else if (fastcmp(param, "noskew") && fastcmp("true", val))
-		sides[i].flags |= GET_SIDEFLAG_EDGENOSKEW(which);
+		overlay->flags |= SIDEOVERLAYFLAG_NOSKEW;
 	else if (fastcmp(param, "wrap") && fastcmp("true", val))
-		sides[i].flags |= GET_SIDEFLAG_EDGEWRAP(which);
+		overlay->flags |= SIDEOVERLAYFLAG_WRAP;
 }
 
 static void ParseTextmapSidedefParameter(UINT32 i, const char *param, const char *val)
@@ -2240,9 +2240,9 @@ static void WriteTextmapEdgeTexture(const char *prefix, unsigned i, side_t *side
 		fprintf(f, "%s""scalex = %f;\n", prefix, FIXED_TO_FLOAT(side->overlays[i].scalex));
 	if (side->overlays[i].scaley != FRACUNIT)
 		fprintf(f, "%s""scaley = %f;\n", prefix, FIXED_TO_FLOAT(side->overlays[i].scaley));
-	if (side->flags & GET_SIDEFLAG_EDGENOSKEW(i))
+	if (side->overlays[i].flags & SIDEOVERLAYFLAG_NOSKEW)
 		fprintf(f, "%s""noskew = true;\n", prefix);
-	if (side->flags & GET_SIDEFLAG_EDGEWRAP(i))
+	if (side->overlays[i].flags & SIDEOVERLAYFLAG_WRAP)
 		fprintf(f, "%s""wrap = true;\n", prefix);
 }
 
@@ -3101,7 +3101,6 @@ static void P_LoadTextmap(void)
 		sd->offsety_top = sd->offsety_mid = sd->offsety_bottom = 0;
 		sd->scalex_top = sd->scalex_mid = sd->scalex_bottom = FRACUNIT;
 		sd->scaley_top = sd->scaley_mid = sd->scaley_bottom = FRACUNIT;
-		sd->flags = 0;
 		sd->toptexture = R_TextureNumForName("-");
 		sd->midtexture = R_TextureNumForName("-");
 		sd->bottomtexture = R_TextureNumForName("-");
@@ -3110,6 +3109,7 @@ static void P_LoadTextmap(void)
 			sd->overlays[j].texture = R_TextureNumForName("-");
 			sd->overlays[j].offsetx = sd->overlays[j].offsety = 0;
 			sd->overlays[j].scalex = sd->overlays[j].scaley = FRACUNIT;
+			sd->overlays[j].flags = 0;
 		}
 		sd->sector = NULL;
 		sd->repeatcnt = 0;

src/r_defs.h

@@ -613,19 +613,17 @@ typedef struct line_s
 // Don't make available to Lua or I will find where you live
 enum
 {
-	SIDEFLAG_EDGENOSKEW1 = 1<<7,
-	SIDEFLAG_EDGENOSKEW2 = 1<<8,
-	SIDEFLAG_EDGENOSKEW3 = 1<<9,
-	SIDEFLAG_EDGENOSKEW4 = 1<<10,
-
-	SIDEFLAG_EDGEWRAP1   = 1<<11,
-	SIDEFLAG_EDGEWRAP2   = 1<<12,
-	SIDEFLAG_EDGEWRAP3   = 1<<13,
-	SIDEFLAG_EDGEWRAP4   = 1<<14
+	SIDEOVERLAYFLAG_NOSKEW = 1<<0,
+	SIDEOVERLAYFLAG_WRAP   = 1<<1
 };
 
-#define GET_SIDEFLAG_EDGENOSKEW(which) (SIDEFLAG_EDGENOSKEW1<<(which))
-#define GET_SIDEFLAG_EDGEWRAP(which) (SIDEFLAG_EDGEWRAP1<<(which))
+typedef struct
+{
+	INT32 texture;
+	fixed_t offsetx, offsety;
+	fixed_t scalex, scaley;
+	UINT8 flags;
+} side_overlay_t;
 
 typedef struct
 {
@@ -642,18 +640,12 @@ typedef struct
 	fixed_t scalex_top, scalex_mid, scalex_bottom;
 	fixed_t scaley_top, scaley_mid, scaley_bottom;
 
-	UINT16 flags;
-
 	// Texture indices.
 	// We do not maintain names here.
 	INT32 toptexture, bottomtexture, midtexture;
 
 	// Upper and lower overlays for top and bottom textures
-	struct {
-		INT32 texture;
-		fixed_t offsetx, offsety;
-		fixed_t scalex, scaley;
-	} overlays[NUM_WALL_OVERLAYS];
+	side_overlay_t overlays[NUM_WALL_OVERLAYS];
 
 	// Linedef the sidedef belongs to
 	line_t *line;

src/r_segs.c

@@ -647,7 +647,7 @@ static void R_RenderExtraTexture(drawseg_t *ds, unsigned which, INT32 x1, INT32
 	mfloorclip = overlayopening[1];
 	mceilingclip = overlayopening[0];
 
-	if (sidedef->flags & GET_SIDEFLAG_EDGEWRAP(which))
+	if (sidedef->overlays[which].flags & SIDEOVERLAYFLAG_WRAP)
 	{
 		fixed_t high, low;
 
@@ -683,8 +683,8 @@ static void R_RenderExtraTexture(drawseg_t *ds, unsigned which, INT32 x1, INT32
 				P_GetSectorCeilingZAt(frontsector, ds_p->rightpos.x, ds_p->rightpos.y)
 			);
 			low = min(
-				P_GetSectorFloorZAt(backsector, ds_p->leftpos.x, ds_p->leftpos.y),
-				P_GetSectorFloorZAt(backsector, ds_p->rightpos.x, ds_p->rightpos.y)
+				P_GetSectorFloorZAt(frontsector, ds_p->leftpos.x, ds_p->leftpos.y),
+				P_GetSectorFloorZAt(frontsector, ds_p->rightpos.x, ds_p->rightpos.y)
 			);
 		}
 
@@ -2029,8 +2029,8 @@ static void R_AddOverlayTextures(fixed_t ceilingfrontslide, fixed_t floorfrontsl
 	if (!backsector)
 	{
 		// If one-sided, render just the upper top and the lower bottom overlays
-		overlaytexture[0] = texnums[0] ? texnums[0] : texnums[2];
-		overlaytexture[3] = texnums[1] ? texnums[1] : texnums[3];
+		overlaytexture[0] = texnums[0];
+		overlaytexture[3] = texnums[3];
 	}
 	else
 	{
@@ -2067,7 +2067,7 @@ static void R_AddOverlayTextures(fixed_t ceilingfrontslide, fixed_t floorfrontsl
 
 			rw_overlay[i].invscalex = FixedDiv(FRACUNIT, rw_overlay[i].scalex);
 
-			if (sidedef->flags & GET_SIDEFLAG_EDGENOSKEW(i))
+			if (sidedef->overlays[i].flags & SIDEOVERLAYFLAG_NOSKEW)
 			{
 				if (IS_BOTTOM_EDGE_TEXTURE(i))
 				{