Env fog controller

GoldSrc

Source Engine

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Class hierarchy
CFogController ↳CBaseEntity
fogcontroller.cpp

This is a preserved entity in
If the game has round restart mechanics this entity may not behave as expected.

env_fog_controller is a logical entity available in all Source games.

This entity determines the properties of aerial fog for the whole map.

Tip:In multiplayer games, fog may be changed per-client by sending the player entity (probably best accessed through !activator) a SetFogController input. (Also applies to single player sessions, like in )

In , multiple env_fog_controllers may be used in conjunction with fog_volumes to create different fog effects where needed. In addition, an env_fog_controller can be set as the Master fog controller under flags, in cases where a fog_volume is not tied to any specific env_fog_controller, or if no fog_volume is used in a region.

Adding fog to a map can cause/require changes to the lighting for realism. Light is scattered and absorbed as it passes through fog. The denser the fog, the greater the effect:

• Falloff - (or attenuation) is the rate at which light intensity decreases over distance. Falloff distance decreases as fog gets thicker.
• Tyndall effects - can be seen when the fog particles reflect light toward the viewer. Halos and light beams become more visible as fog gets thicker.
• Diffused Lighting - the boundary-line between light and shadow becomes more blurred (diffuse) as fog gets thicker. See Lightmap Scale and shadow_control's "distance" parameter.

Note:The 3D Skybox fog levels set by the sky_camera parameters should correspond to your env_fog_controller settings.

Radial fog

Older Source games (all - games) render fog as a plane a certain distance away from the camera. This method is bad, as rotating the camera will strengthen or weaken the apparent amount of fog in a particular spot, even though the viewer hasn't moved at all. If both sky_camera and env_fog_controller distance don't match its value, also makes objects like trees, grass looks like they're slightly glowing when looking at a different angle.

In Left 4 Dead onward, as well as Half-Life 2 (since 20th Anniversary Update), Portal (May 20, 2025), all Team Fortress 2 branch games, and Mapbase, this is fixed by implementing a new radial method which is independent from the viewing angle. However, in the Team Fortress 2 branch, Portal and Half-Life 2, radial fog must be manually enabled by changing the "Use Radial Fog? (fogRadial)" keyvalue. A console command called r_radialfog_force (no cheats required) is available, to switch between radial fog and planar-based fog in-game, without recompiling the map. You can also use fog_radial and fog_radial_skybox (requires fog_override 1 and sv_cheats 1).

Note:Radial fog are enabled by default on all official Team Fortress 2 maps, even if "Use Radial Fog?" is set to "No".

Comparison between planar-based fog and radial fog. Screenshot from Counter-Strike: Source on Team Fortress 2 branch.

Flags

Master : [1]

If multiple env_fog_controllers are active, this one will always take priority. There must be at least one fog_volume in the map to work!

Keyvalues

Fog Enable (fogenable) <boolean>

Make fog start active.

Fog Start (fogstart) <float>

How far away from the viewer the fog should start.

Fog End (fogend) <float>

How far away from the viewer the fog reaches Fog Max Density.

Fog Max Density (fogmaxdensity) <float>

Maximum density the fog may reach. Expressed as a decimal percent, so for 45% put 0.45.

Far Z Clip Plane (farz) <integer>

Anything beyond this distance in world units will not be rendered. This should be higher than Fog End. If this value is -1 (default), the game will use a distance of 28377.9204312 units. If this is used, Fog Max Density should be set to 1 otherwise the void may be visible.

Warning:See the r_farz warning at sv_cheats

Note:This value is used as vis radius by VVIS

Primary Fog Color (fogcolor) <color255>

Primary Fog Color.

Secondary Fog Color (fogcolor2) <color255>

Secondary Fog Color. If Fog Blend is disabled, this color will never appear.

Primary Fog Color (HDR Override) (fogcolor_hdr) <color255> (only in 20th)

Override Primary Fog Color for HDR.

Secondary Fog Color (HDR Override) (fogcolor2_hdr) <color255> (only in 20th)

Override Secondary Fog Color for HDR. If Fog Blend is disabled, this color will never appear.

Fog Blend (fogblend) <boolean>

Enables color blending between Primary Fog Color and Secondary Fog Color. When the viewer looks in the Primary Fog Direction, fog will appear as the Primary color. When looking away from the specified direction, fog appears as the Secondary color. If the camera is not pointed directly at or away from the direction, a blend of the two colors will result. Sunlight with a Yaw of 45 degrees and a Pitch of -45 degrees could be enhanced using a Primary Fog Direction of "-1 -1 1", a Primary Fog Color of "120 110 100" and a Secondary Fog Color of "80 70 60".

Primary Fog Direction (fogdir) <vector>

A vector (given by three space-separated numbers X Y Z) which the viewer camera is checked against to figure out the blend between the primary and secondary fog colors.

Use Angles for Fog Dir (use_angles) <boolean>

Use Pitch Yaw Roll for the Fog Blend direction instead of Primary Fog Direction. There isn't much use for this unless you want the direction to rotate.

Use Radial Fog? (fogRadial) <boolean> (only in 20th, , )

Use radial fog instead of planar-based fog. Only in Half-Life 2 20th Anniversary Update, Half-Life: Source (which runs on top of HL2 20th Anniversary base), aswell as all games on Team Fortress 2 branch (since Feb 18, 2025 update).
Radial fog is always used on Left 4 Dead onward.

Interpolate time (foglerptime) <float>

Fade time for the StartFogTransition input.

HDR Color Scale (HDRColorScale) <float> (in all games since )

Multiplier for fog color when in HDR mode.

Zoom Fog Scale (ZoomFogScale) <float> (in all games since )

Scalar for fog start and end distances when the player is looking through a gun's scope (e.g. AWP).

Inputs

TurnOn

Turns the fog on.

TurnOff

Turns the fog off.

SetAngles <anglesRedirectInput/Vector>

Sets the angles to use for the Primary Fog Direction.

SetStartDist <floatRedirectInput/float>

Sets the Fog Start distance.

SetEndDist <floatRedirectInput/float>

Sets the Fog End distance.

SetColor <color255RedirectInput/color32>

Sets the Primary Fog Color.

SetColorSecondary <color255RedirectInput/color32>

Sets the Secondary Fog Color.

SetColorHDR <color255RedirectInput/color32> (only in 20th)

Override Primary Fog Color for HDR.

SetColorSecondaryHDR <color255RedirectInput/color32> (only in 20th)

Override Secondary Fog Color for HDR.

SetRadial <booleanRedirectInput/boolean> (only in 20th, )

Set the fog to be radial or not (planar). 0 = Planar, 1 = Radial.

SetFarZ <integerRedirectInput/integer>

Sets the Far Z Clip Plane distance.

SetMaxDensity <floatRedirectInput/float> !FGD

Sets the Fog Max Density.

Note:This input may not be in most FGD files but works in . Does it work in others games ? ^[confirm]

Set2DSkyboxFogFactor <floatRedirectInput/float> (in all games since )

Set the current amount of fog to blend into the 2D skybox. Expressed as a decimal percent, so for 45% put 0.45. only.

SetZoomFogScale <floatRedirectInput/float> (in all games since )

Sets the Zoom Fog Scale.

SetColorLerpTo <color255RedirectInput/color32> (in all games since )

Stores a value for Primary Fog Color that is set once the StartFogTransition input fires.

SetColorSecondaryLerpTo <color255RedirectInput/color32> (in all games since )

Stores a value for Secondary Fog Color that is set once the StartFogTransition input fires.

SetStartDistLerpTo <floatRedirectInput/float> (in all games since )

Stores a value for Fog Start that is set once the StartFogTransition input fires.

SetEndDistLerpTo <floatRedirectInput/float> (in all games since )

Stores a value for Fog End that is set once the StartFogTransition input fires.

SetMaxDensityLerpTo <floatRedirectInput/float> (in all games since )

Stores a value for Fog Max Density that is set once the StartFogTransition input fires.

Note:This one does not have any non-"LerpTo" counterpart. ^[confirm] Is this still true ? See SetMaxDensity input.

Set2DSkyboxFogFactorLerpTo <floatRedirectInput/float> (in all games since )

Set the current amount of fog to blend into the 2D skybox. Expressed as a decimal percent, so for 45% put 0.45. This will only change once the StartFogTransition input fires. only.

StartFogTransition  (in all games since )

When fired, the fog fades to any new values sent through the "LerpTo" inputs. Fade time is determined by the Interpolate time keyvalue.

Bug:Does not work correctly in some games. The fog will transition to nothing and then abruptly change to the new values at the end of the interpolation time in .  [todo tested in ?]

Todo: What other games have this bug? (Works perfectly in for example)

ActivateAllPlayers  (only in )

Turns this fog on for all connected players

See also

• fog_volume
• Fog tutorial
• Fog Basics
• Dust, Fog, & Smoke