L4D Mapping Notes
This page contains a rough collection of notes and incomplete articles related to L4D mapping. Most of the contents will not likely be completed until after Left 4 Dead's SDK is released, upon which they should be split off into articles of there own.
- 1 Introduction sequences
- 2 Later Spawn areas
- 3 The Director
- 4 Item and weapon caches
- 5 Panic events
- 6 Crescendo events
- 7 One method for changing levels
- 8 More on building the navigation mesh
- 9 Nav Attribute Descriptions
- 10 The Nav GUI
- 11 Finale
- 12 Notes
In the first chapter, to create the "zoom in effect" the game uses 4 "
info_survivor_position" entities and 4 "
point_viewcontrol_survivor" entities. Although leaving these 8 entities out won't create any problems, the introduction sequence should at least be considered as a final touch before releasing a map to the public.
My Output > Target Entity Target Input Parameter Delay Only Once OnTrigger director ForceSurvivourPosition 0.00 No OnTrigger director ReleaseSurvivourPosition 0.01 No
Later Spawn areas
For spawn areas in later chapters of the campaign, you do not have to keep using the same weapons you used in the first map as most players will likely have already swapped these for other more powerful weapons they've found along the way. These more powerful weapons you can use in the spawn areas for the later chapters will usually consist of:
weapon_autoshotgun_spawn, and a
Instead of fixed spawn points for enemies, Left 4 Dead uses the "Director" to place enemies and items in varying positions and quantities based upon each player's current situation, status, skill and location.
My Output > Target Entity Target Input Parameter Delay Only Once OnGameplayStart relay_intro_start Trigger 0.00 No
Creating areas for the infected to spawn.
The director will spawn infected that are out of the line of sight, so for particularly difficult maps have plenty of places out of sight. Sometimes a spawn area is outside the normal player boundary. To let the infected into the playable area, there must be a
func_simpleladder (with team set to 2) on the back side of the barrier, for them to climb over.
Item and weapon caches
Setting spawn flags to randomize the locations.
- for the green oxygen tank:
- for the red gas can:
- for the white propane tank:
- for the green oxygen tank:
Triggering the info_director and summoning the horde.
- Car alarms
- Door alarms
- Fire alarms
- Smoke detectors
- Metal detectors
Intermediate objectives. "Crescendo Events" are much like smaller versions of the big finale battle at the end of each campaign, and occur at interesting places along the way. There setup is very similar to panic events, except that they cannot be skipped. An in-game example being the Waterworks part of No Mercy, the survivors must fend off a horde of infected while they wait for the lift to arrive.
My Output > Target Entity Target Input Parameter Delay Only Once OnTrigger director PanicEvent 1.00 No
One method for changing levels
trigger_changelevel inside the safe house at the end of the level and have it come in contact with the floor space inside the room. The trigger brush doesn't necessarily have to overlap the floor space, but it does have to at least touch it, or a good portion of where the nav square(s) will be generated. If the
trigger_changelevel doesn't come in contact with the floor space, you will have nav errors when the map is loaded and may have to manually mark the nav squares.
Make sure the
info_landmark is named and that the landmark name is specified inside the
trigger_changelevel settings along with the name of the next map to be loaded. For the
prop_door_rotating_checkpoint, make sure the model is set to
models/props_doors/checkpoint_door_02.mdl and the "Starts Open" option is checked inside the "flags" tab.
You need to have the map already compile and loaded, then open up the console in game and type the following:
The map is reloaded twice during the process, once after
nav_generate and again after
nav_analyze, but the game should stay in edit mode when the map is reloaded.
Keep in mind, while the console commands above will build a basic mesh, it will be far from perfect and thus should only be used for testing purposes. A good nav mesh should be thoroughly examined and edited before releasing a map, which can often be a good deal of work depending on the map's structure. For this reason, its recommended that you save fine tuning the mesh until after you are completely finished with the map's layout. Significant changes in a maps structure may render an older nav mesh useless requiring it to be rebuilt from scratch.
- BATTLESTATION: Seems to be used to mark defense areas near crescendo events
- CHECKPOINT: This is used in both the starting and ending checkpoints. (safe rooms) This is how the game knows whether the survivors have left the safe room or not, and whether they have reached the end of a level or not. (I think. There don't appear to be any triggers doing this in the ones I decompiled.)
- EMPTY: this will keep zombies from spawning in certain areas of the map. Large chunks of the level are marked empty/not empty. I've had some trouble with it working correctly when EMPTY was not the only marking assigned to the nav area.
- ESCAPE ROUTE: Path that links the beginning checkpoint to the ending checkpoint or finale.
- FINALE: The area is used in the finale crescendo event. The nav areas marked FINALE determine where the infected spawn and swarm from after the radio is triggered twice, areas not marked FINALE will _not_ be used by the director for spawning infected once the finale sequence has been triggered. When the survivors touch a finale nav square they will announce "where almost outta here" or similar.
- JUMP: (Probably not L4D Specific) I found one area in the maps I looked at marked as "jump" - on top of a subway car only reachable by infected who could jump. This area likely signifies a place you must jump to somehow in order to reach.
- NOT_CLEARABLE: Not sure what this does. This doesn't appear to be used.
- NO_MOBS: Don't allow mobs to spawn in the area. This isn't used very often - one location is in the "drainage" level of the Death Toll campaign. It is used in the long pipes. This forces more mobs to spawn in the top of the right-side pipe while you're inside.
- OBSCURED: The players cannot see this area at all (or hardly at all). The game uses these locations to spawn the massive hordes (if possible) - otherwise it will use areas that are far out of players' potentially visible sets of visleaves. (I think)
- PLAYER_START: This attribute is used in the exact nav mesh area(s) that the players spawn in. This appears to only be used in the very first level of each campaign - likely because after the first level it cannot be guaranteed where a player will spawn into the game (since you load relative to the landmark).
- RESCUE_CLOSET: Marks off the location of rescue closets inside the level
- RESCUE_VEHICLE: This nav attribute marks the inside of a rescue vehicle, this nav will be locked until the finale sequence has been completed and the trigger_finale receives a "FinaleEscapeVehicleReadyForSurvivors" input.
- STOP_SCAN: Not sure what this does. This doesn't appear to be used.
- Fog: Whether or not the area has fog associated with it.
- Incoming/Outgoing: (Probably not L4D Specific) Likely used to select areas with incoming or outgoing path information.
- Max Light / Min Light: (Not L4D Specific) Used to select areas that have certain levels of light. (.25 max / 0 min for a dark place, 1 max / .75 min for a bright place)
- Place: (Probably not L4D Specific) "Place" is the term used in nav creation to name specific areas. This is likely a way to select named/unnamed areas only.
Ending the campaign. In the final chapter of each campaign, the players must defend a position from an onslaught of Infected until a rescue vehicle arrives.
Setting up the radio
- Entity: trigger_finale
- Name: FinaleRadio
- Description: This single entity is responsible for starting the finale sequence after being triggered twice.
- FinaleEscapeStarted - ABOUT: Basically means "when the finale is finished, fire this output". This is usually used to trigger a relay to summon the rescue vehicle.
- Note:The VALVe maps use two seperate "func_buttons" for triggering this entity. This is possibly a last minute workaround on VALVe's part when they found playtesters starting finale sequences "by accident" since the trigger_finale can recieve "use" input itself when it's world model is set.
Adding the rescue vehicle
- Entity: logic_relay
- Name: EscapeRelay
- Description: Triggered once the finale sequence has been completed. Starts the escape vehicles animations and moves it to the RESCUE_VEHICLE nav squares. When the vehicle is in place, the func_brush entities used to reach the RESCUE_VEHICLE nav areas are enabled.
- FinaleEscapeVehicleReadyForSurvivors - This "unlocks" the "RESCUE_VEHICLE" nav squares, upon which the survivor bots will rush towards them. Its a good idea to delay this to give the rescue vehicle enough time to get in position.
- Note:The VALVe maps also have trigger_hurt and trigger_push entities used to clear a path for the rescue vehicle and simulate it running something over.
- Entity: func_door, Name: RescueBrush
- Entity: func_door, Name: RescueBrushDr1
- Starts Open: Yes
- Parent: RescueBrush
- Entity: func_door, Name: RescueBrushDr2
- Starts Open: Yes
- Parent: RescueBrush
- Entity: func_brush, Name: RescueBrushRamp
- Start Disabled: Yes
- Solidity: Toggle
- Entity: trigger_multiple, Name: TriggerEscape
- Description: Set to be enabled after the rescue vehicle animation finishes. When activated, triggers the VehicleLeaveRelay.
- Entity: logic_relay, Name: VehicleLeaveRelay
- Description: Used for controlling the rescue vehicle exit animations and firing the OutroRelay
Rolling the credits
- Entity: logic_relay, Name: OutroRelay
- Description: Ends the map and starts up the credits screen.
- FinaleEscapeForceSurvivorPositions - This enables the "info_survivor_position" entities to remove players from the battelfield.
- Entity: env_fade Name: FadeOutro
- Entity: env_outtro_stats Name: OutroStats
- Entity: info_game_event_proxy Name: InstructorFinale
- Entity: info_survivor_position Name: survivor_pos1
- Entity: info_survivor_position Name: survivor_pos2
- Entity: info_survivor_position Name: survivor_pos3
- Entity: info_survivor_position Name: survivor_pos4
- Entity: point_viewcontrol_multiplayer Name: EndCamera
- Type: prop_door_rotating
- Frame Dimensions: width: 56, height: 104
- World Model: models/props_doors/doormainmetal01.mdl
- For a basic tutorial on creating and setting up doors in Left 4 Dead, see:
Doors in Left4Dead (l4dmaps.net)