Climbable trapdoors if connected to a ladder.

Minecraft.World/LivingEntity.cpp

@@ -986,9 +986,31 @@ bool LivingEntity::onLadder()
 	int yt = Mth::floor(bb->y0);
 	int zt = Mth::floor(z);
 
-	// 4J-PB - TU9 - add climbable vines
 	int iTile = level->getTile(xt, yt, zt);
-	return  (iTile== Tile::ladder_Id) || (iTile== Tile::vine_Id);
+	switch (iTile)
+	{
+	case Tile::ladder_Id:
+	case Tile::vine_Id: // 4J-PB - TU9 - add climbable vines
+		return true;
+	case Tile::trapdoor_Id: // hexagonny - add climbable (opened) trapdoors
+	{
+		if ((level->getData(xt, yt, zt) & 0x4) != 0)
+		{
+			switch (level->getTile(xt, yt + 1, zt))
+			{
+			case Tile::ladder_Id:
+			case Tile::vine_Id:
+				return false; // Opened trapdoor should only be climbable when it's only at the top.
+			default:
+				return level->getTile(xt, yt - 1, zt) == Tile::ladder_Id;
+			}
+		}
+		break;
+	}
+	default:
+		break;
+	}
+	return false;
 }
 
 bool LivingEntity::isShootable()

Minecraft.World/TrapDoorTile.cpp

@@ -50,6 +50,21 @@ AABB *TrapDoorTile::getTileAABB(Level *level, int x, int y, int z)
 
 AABB *TrapDoorTile::getAABB(Level *level, int x, int y, int z)
 {
+	int data = level->getData(x, y, z);
+	if (isOpen(data))
+	{
+		int xt = x, zt = z;
+		if ((data & 3) == 0) zt++;
+		if ((data & 3) == 1) zt--;
+		if ((data & 3) == 2) xt++;
+		if ((data & 3) == 3) xt--;
+
+		if (level->getTile(x, y - 1, z) == Tile::ladder_Id && attachesTo(level->getTile(xt, y, zt)))
+		{
+			return nullptr; // No collision when open above ladder (add is attached to a block)
+		}
+	}
+	// Default behaviour
 	updateShape(level, x, y, z);
 	return Tile::getAABB(level, x, y, z);
 }