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Water Volumes are shape objects which can be used in a variety of different circumstances, such as rivers, lakes, pools, puddles or even oceans.


For the detailed description of the Shape area properties, please refer Shape.




Specifies how deep the water volume should be.


Specifies at which speed the water should be moving. Not used for water volumes, inherited from Area Shapes.

Fog Density

Specifies the density of the fog.

Fog Color

Lets you choose the underwater fog color.

Fog Color Multiplier

Lets you choose how bright the underwater fog color is.

Fog Color Affected By Sun

If true, Sun Color value set in the Environment Editor will affect fog color of the water volume.

Fog Shadowing

If enabled, the surface of the water volume will receive shadows. You can control the shadow darkness, valid input 0-1.

NOTE: r_FogShadowsWater needs to be set to '1' for this to function, which is currently only enabled on Very High Spec.
If you use Vol Fog Shadows in Level Settings, you lose control of shadow darkness (automatically set to full).
The benefit here is that the fog in the water volume will receive volumetric shadows! See the below Usage Examples section for comparisons.

Cap Fog At Volume Depth

If false, fog will continue to render below the specified Depth of water volume.

U Scale

Specifies how much the water surface (bump) texture is tiled horizontally.

V Scale

Specifies how much the water surface (bump) texture is tiled vertically.


Enables Caustics for this entity.

Caustic Intensity

Controls the intensity of the caustics (this scales the normals of the surface when rendering to the caustic map, producing stronger caustics).

Intensity 1Intensity 4Intensity 8

Caustic Tiling

This is a multiplier for the tiling applied to the surface normals during caustic generation. It allows you to scale the caustics generation independently from the surface material in cases of strong tiled normals or vice-versa.

Tiling 1Tiling 4Tiling 8

Caustic Height

Controls the height above the water entity in which caustics can be cast. This can be used to cause caustics on overhangs and other nearby objects.

Height 1Height 3Height 6


Fixed Volume

Will trace a ray down from the volume's initial shape's center to find a 'vessel' entity and 'spill' the requested amount of water into it. For static entities, it'll try to boolean-merge any surrounding static that intersects with the first vessel (use "No Dynamic Water" flag on brushes that don't need that). Volume's shape will then be adjusted dynamically to match the vessel's geometry.

Volume Accuracy

Water level will be calculated until the resulting volume is within this (relative) difference from the target volume (if it's set to 0 it'll run up to a hardcoded iteration limit).

Extrude Border

Will extrude the border by this distance. It's particularly useful if wave sim in on since waves can raise the surface and thus reveal open edges if they lie exactly on the vessel geometry.

Convex Border

Will take convex hull of the border. Mainly useful if the border would otherwise have multiple contours, which areas don't support.

Object Size Limit

The Only object that has volume larger than this will take part in water displacement (set in fractions of FixedVolume).

Wave Sim Cell

Size of a cell for wave simulation (0 means no waves). Can be enabled regardless of whether FixedVolume is used or not. Use smaller sizes like 0.05-0.2m to have enough details on smaller volumes, and larger ones if you need to fill a large vessel/area.

Wave Speed

Sets how "fast" the water looks.

Wave Damping

Standard damping.

Wave Timestep

Might need to be decreased to maintain stability if more aggressive values for speed are used.

Min Wave Vel

Sleep threshold for the simulation.

Depth Cells

Sets how deep the moving layer of water is (in WaveSimCell units). Larger values make waves more 'dramatic'.

Height Limit

Sets a hard limit on wave height (in WaveSimCell units).


Sets how strongly moving objects transfer velocity to the water.

Sim Area Growth

If changing water level is expected to make the area expand, the wave sim grid should take it into account from the beginning. This sets the projected growth in fractions of the original size. If wave sim is not used this has no effect.

Water volumes also have special interpretation of helper types (use a_[suffix] to show helpers for areas only). a_g will draw the outline and the tessellated surface, a_gj will draw the wave sim as a checkerboard-like heightfield, a_l will draw the vessel geometry (a union of all overlapping potential vessels).

Console Variables






Enables or disables caustics for water volumes

0 - 1 (default depends on system - currently 0 on all except PC high-spec).


Sets the density of the grid mesh.

16 - 256 (default is 128 for lower specs, 256 for high specs).


Sets the maximum view distance caustics are visible.

Anything. Default 25.


Sets the resolution of the caustics map/g-buffer.

Texture resolution. Default 1024 for high specs, 512 for low specs.


Sets the snap factor of the caustic render, helps prevent aliasing during motion.

Anything. Default: 0.1.

Usage Examples


Caustics are a great way to give your water volumes a much bigger visual presence and involve them more into the scenes you create. For more info see Water Volume Caustics.

Caustics OffCaustics On


Fog Shadows gives real visual depth to your water volumes, also making optional use of the global Vol Fog Shadows function available in the Level Settings.

Due to a technical limitation, using VolFogShadows will limit the opacity function of the FogShadowing param to be either off or full.

VolFogShadows DisabledVolFogShadows Enabled
FogShadowing 0FogShadowing 0.25FogShadowing 0.5


The Depth parameter defines both visual and physical depth of the water volume. Things such as the underwater distortion effect is based off the Depth setting.

Depth 0Depth 10


With this disabled, the fog settings from the water volume will display infinitely on the Z axis (downwards).

A usage example would be if you had a room that was accessible underneath a water volume, then you would probably activate this setting to prevent the fog from being seen inside the room.

Depth 0 / Cap Fog FalseDepth 0 / Cap Fog True


Although the Height parameter is not used for water volumes, it can be useful for visualizing the edges of the volume which would typically be hidden underground.


Although Speed isn't supported by water volumes (because there's no easy way to define direction on an arbitrarily user-designed shape with infinite results) there's an easy way you can 'physicalize' your water volumes.

Rivers support the Speed parameter and can be placed without any visual representation by simply not applying a material to the object. Layering Rivers on top of your Water volumes (remember to match depths!)

When placing Rivers for this use, make sure to keep them straight (the 'Speed' is applied only for the initial vector and cornering is not supported) and overlap where you want them to change course so they don't get stuck.

In the above example, we have three main Rivers (with outside supports to simulate from waterfall) atop the main water volume, carrying several RigidBodyEx entities along for a ride.

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