func_precipitation
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func_precipitation
is a brush entity available in all Source games. It creates rain, snow, or ash inside its volume.
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CPrecipitation |
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If the game has round restart mechanics this entity may not behave as expected:
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Keyvalues
- Name (targetname) <string>[ Edit ]
- The name that other entities refer to this entity by, via Inputs/Outputs or other keyvalues (e.g.
parentname
ortarget
).
Also displayed in Hammer's 2D views and Entity Report.See also: Generic Keyvalues, Inputs and Outputs available to all entities
- Density (0-100%) (renderamt) <integer>
- This is the amount of particles that fall down from the top side of the brush. However, distance from first particle to second depends on a brush volume size!
- Color (R G B) (rendercolor) <color255>
- Color added to sprites which are rendered transparently (probably rain and snow particles)
- Precipitation Type (preciptype) <choices>
- Precipitation type
Type | Availability | Description |
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Rain | Seen in CS:S map "de_aztec " |
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Snow | Identical to Rain, use "Snowfall" instead. | |
Ash | Seen throughout Half-Life 2: Episode One
![]() materials/effects/fleck_ash* and materials/effects/ember_swirling001 files from ep1_pak_dir.vpk and ship it with your game/map. |
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Snowfall | Seen in DoD:S map "dod_colmar " |
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Particle Rain | (in all games since ![]() |
Seen in Left 4 Dead's "No Mercy" campaign, CS:GO map "de_aztec "Particle rain with slight mist and refraction. |
Particle Ash | (in all games since ![]() |
Seen in in Left 4 Dead's "Dead Air" campaign. |
Particle Rain Storm | (in all games since ![]() |
Seen in Left 4 Dead 2's "Hard Rain" and "The Passing" campaigns. Particle rain with no mist/refraction and more angled particles. Alpha values over 100 enable an additional flying leaves effect seen during the storm event. |
Particle Snow | (in all games since ![]() |
Seen in CS:GO map "ar_monastery " |
Particle Bugs | (only in ![]() |
Seen in Left 4 Dead 2's "Swamp Fever" campaign. Particle flying bugs. In later games, this value is used by Particle Snow instead. |
Particle Smoke | (only in ![]() |
Seen in Left 4 Dead 2's "Dead Center" campaign. Particle smoke with variable density. |

Inputs
- Alpha <integer > !FGD
- Changes the density of the rain, and may add additional particle effects like fog or leafs. It accepts inputs from -1 to 255.
Related Console Commands
There are a number of console commands that control precipitation rendering. See the Precipitation issues page for details on various issues and workarounds involving this entity.
Command Name Value Description r_RainParticleDensity <float> Set the density to enable or disable any precipitation particle. Value 1 to enable and 0 to disable. r_rainalpha <float> Adjusts transparency of rain particles. r_rainProfile <bool> Displays stats on rain rendering costs. r_RainHack <bool> Overrides density values set in Hammer. Enabling will result in longer and more dense rain than at 100%. Can help solve visibility issues. Note:Rain may fall through brushes when this command is enabled.
r_rainspeed <float> Lower values will cause rain to disappear sooner and fall slower. Default value is 600.0f r_RainSideVel <float> Controls sideways movement of the rain particles. r_RainSimulate <bool> Toggles animation on the rain; freezes the rain when set to 0. r_rainwidth <float> Widens the rain's alpha to desired value. Default value is 0.5 r_RainRadius <float> Distance from the brush where the rain starts/stops rendering. r_rainlength <float> Changes the length of the rain particles. Default value is 0.1f r_RainSplashPercentage <float> Percent chance of splash particles spawning when a particle is used. r_raindensity <float> No function. Use r_RainParticleDensity
instead.r_rainalphapow <float> Raises the value of r_rainalpha
exponentially.Confirm:Some say this has no effect?

func_precipitation
brushes should not overlap func_smokevolume
brushes, as it can freeze the game. The exact cause of this is not clear.
