Climbable trapdoors if connected to a ladder.

### Previous Behavior
Trapdoors still has collision even if opened, making it difficult to climb with.

### New Behavior
- Added a new condition in `LivingEntity::onLadder()` in case it's a trapdoor, then return as true (as if its a ladder).
- If there's a ladder under the (opened) trapdoor, then its collision box returns as a nullptr.

**Files:**
- `LivingEntity.cpp`
- `TrapDoorTile.cpp`
**Methods:**
- `LivingEntity::onLadder()`
- `TrapDoorTile::getAABB(Level *level, int x, int y, int z)`

Minecraft.World/LivingEntity.cpp

@@ -986,9 +986,30 @@ 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
+	{
+		int data = level->getData(xt, yt, zt);
+		bool isOpen = (data & 0x4) != 0;
+		if (isOpen)
+		{
+			int belowTile = level->getTile(xt, yt - 1, zt);
+			if (belowTile == Tile::ladder_Id)
+			{
+				return true;
+			}
+		}
+		break;
+	}
+	default:
+		break;
+	}
+	return false;
 }
 
 bool LivingEntity::isShootable()

Minecraft.World/TrapDoorTile.cpp

@@ -50,6 +50,18 @@ 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);
+	bool isOpen = (data & 0x4) != 0;
+
+	if (isOpen)
+	{
+		int belowTile = level->getTile(x, y - 1, z);
+		if (belowTile == Tile::ladder_Id)
+		{
+			return nullptr; // No collision when open above ladder
+		}
+	}
+	// Default behaviour
 	updateShape(level, x, y, z);
 	return Tile::getAABB(level, x, y, z);
 }