Level Transitions
Level transitions allow you transfer the player from one map to another, essentially making two separate levels seem like one larger map.
Why change levels?
The Source, while expansive, still has limits as to the the amount data that can be processed. Breaking up levels also helps split up the work load and compile times during the design process.
One way transitions
One way transitions prevent the player from traveling back to previously explored areas after being completed.
Two way transitions
Unlike the one way transition described above, a two way level transition allows a player to travel back and forth between two separate maps.
Creating a seamless transition
To create a seamless transition, parts of one level are typically included in the next level being loaded. The exception being "teleportation" style transitions, where the players are transported into an entirely new world or environment.