- added udmf key midtex3dimpassible which causes the midtex to behave like a finite-height impassible line; practically this means the mid texture lets projectiles pass through it.

specs/udmf_zdoom.txt

@@ -95,7 +95,7 @@ Note: All <bool> fields default to false unless mentioned otherwise.
       alpha = <float>;            // Translucency of this line, default is 1.0
       renderstyle = <string>;     // Render style, can be "translucent" or "add",
                                   // default is "translucent".
-      playeruseback = <bool>;   // New SPAC flag, true = player can use from back side.
+      playeruseback = <bool> ;    // New SPAC flag, true = player can use from back side.
       anycross = <bool>;          // New SPAC flag, true = any non-projectile 
                                   // crossing will trigger this line
       monsteractivate = <bool>;   // Monsters can trigger this line.
@@ -109,8 +109,11 @@ Note: All <bool> fields default to false unless mentioned otherwise.
       clipmidtex = <bool>;        // Line's mid textures are clipped to floor and ceiling.
       wrapmidtex = <bool>;        // Line's mid textures are wrapped.
       midtex3d = <bool>;          // Actors can walk on mid texture.
-      checkswitchrange = <bool>;// Switches can only be activated when vertically reachable.
+      midtex3dimpassible = <bool>;// Used in conjuction with midtex3d - causes the mid
-      blockprojectiles = <bool>;// Line blocks all projectiles
+                                  // texture to behave like an impassible line (projectiles
+                                  // pass through it).
+      checkswitchrange = <bool>;  // Switches can only be activated when vertically reachable.
+      blockprojectiles = <bool>;  // Line blocks all projectiles
       blockuse = <bool>;          // Line blocks all use actions
       blocksight = <bool>;        // Line blocks monster line of sight
       blockhitscan = <bool>;      // Line blocks hitscan attacks

src/doomdata.h

@@ -162,6 +162,7 @@ enum ELineFlags
 	ML_BLOCKUSE					= 0x02000000,	// blocks all use actions through this line
 	ML_BLOCKSIGHT				= 0x04000000,	// blocks monster line of sight
 	ML_BLOCKHITSCAN				= 0x08000000,	// blocks hitscan attacks
+	ML_3DMIDTEX_IMPASS			= 0x10000000,	// [TP] if 3D midtex, behaves like a height-restricted ML_BLOCKING
 };
 
 

src/namedef.h

@@ -419,6 +419,7 @@ xx(Passuse)
 xx(Repeatspecial)
 xx(Conversation)
 xx(Locknumber)
+xx(Midtex3dimpassible)
 
 xx(Playercross)
 xx(Playeruse)

src/p_3dmidtex.cpp

@@ -258,6 +258,13 @@ bool P_GetMidTexturePosition(const line_t *line, int sideno, fixed_t *ptextop, f
 
 bool P_LineOpening_3dMidtex(AActor *thing, const line_t *linedef, FLineOpening &open, bool restrict)
 {
+	// [TP] Impassible-like 3dmidtextures do not block missiles
+	if ((linedef->flags & ML_3DMIDTEX_IMPASS)
+		&& (thing->flags & MF_MISSILE || thing->BounceFlags & BOUNCE_MBF))
+	{
+		return false;
+	}
+
 	fixed_t tt, tb;
 
 	open.abovemidtex = false;

src/p_udmf.cpp

@@ -1030,11 +1030,16 @@ public:
 				Flag(ld->flags, ML_BLOCKHITSCAN, key); 
 				continue;
 			
-			// [Dusk] lock number
+			// [TP] Locks the special with a key
 			case NAME_Locknumber:
 				ld->locknumber = CheckInt(key);
 				continue;
 
+			// [TP] Causes a 3d midtex to behave like an impassible line
+			case NAME_Midtex3dimpassible:
+				Flag(ld->flags, ML_3DMIDTEX_IMPASS, key);
+				continue;
+
 			default:
 				break;
 			}
@@ -1081,6 +1086,10 @@ public:
 		{
 			ld->args[1] = -FName(arg1str);
 		}
+		if ((ld->flags & ML_3DMIDTEX_IMPASS) && !(ld->flags & ML_3DMIDTEX)) // [TP]
+		{
+			Printf ("Line %d has midtex3dimpassible without midtex3d.\n", index);
+		}
 	}
 
 	//===========================================================================