Water
Water
is a material shader available in all Source games. It creates water that realistically reflects and refracts the world, and that can flow throughout a map.
Contents
Special behaviour
- Expensive and cheap
-
Water
materials fall into two groups: expensive and cheap. Expensive water reflects and refracts the world in real-time, while cheap water uses an$envmap
and does not refract. Users can disable expensive water rendering through their video options, so always placeenv_cubemap
entities throughout a map. - Above and below
-
Water
actually requires two materials: one for above the surface and one for below. These materials are independent of each other, but for proper effect need to correlate in most areas. - Flow Mapping
- Water can flow in arbitrary directions. It's very tricky to create a flow map by hand however, and the tool Valve used internally hasn't been released.
Shader parameters
Textures


$basetexture
. The surface is a combination of fog color, animated bump map, reflection and refraction.-
$abovewater
<boolean>
- Whether this material is used for above or below the water’s surface.
-
$bottommaterial
<material>
- Required parameter. This is the material (not texture) to use when underneath the water’s surface. The bottom material must have
$reflecttexture
,$abovewater
and$envmap
disabled, but can otherwise do whatever it wants. -
$underwateroverlay
<material>
(New with Half-Life 2: Episode Two / Source 2007) - Applies a refracting screen overlay when the camera is underwater. Generally used with
effects\water_warp01
. Requires$abovewater
to be 0. -
$bumpmap
<texture>
(DX8) -
$normalmap
<texture>
- A Du/dv map for DirectX 8 rendering (
$bumpmap
), and a bump map for DirectX 9 and above ($normalmap
). These should be animated unless the water is to be perfectly still or you're using a flow map, which makes an animated bump map redundant. -
Note:The
$normalmap
parameter is unique to theWater
shader, and uses a normal map. A du/dv map is used for$bumpmap
when using theWater
shader. The$dudvmap
command is obsolete.Tip:Use
$bumptransform
with the TextureScroll proxy to move the normal map in pre-2006 engine branches. -
$dudvframe
<integer>
-
$bumpframe
<integer>
- Frame to start the animated du/dv map and bump map on, respectively. Somewhat confusingly,
$bumpframe
affects$normalmap
, which should be pointing to a bump map. -
$bumptransform
<matrix>
- Transforms the bump map texture.
- The default position is
"center .5 .5 scale 1 1 rotate 0 translate 0 0"
.-
center
defines the point of rotation. Only useful ifrotate
is being used. -
scale
fits the texture into the material the given number of times. '2 1
' is a 50% scale in the X axis. -
rotate
rotates the texture counter-clockwise in degrees. Accepts any number, including negatives. -
translate
shifts the texture by the given numbers. '.5
' will shift it half-way.
-
Note:All values must be included!
Bug: Scaling the texture may cause odd issues where the Texture Lock tool in Hammer will not actually lock the texture in place.
Bug: Rotating textures applied on brushes will rotate around the map origin (confirm: Orangebox engine only?). A fix for this is to change the center position in the VMT to the brush's origin.
-
$scale
<vector2>
- To do: What does this do?
-
$flashlighttint
<float>
(New with Left 4 Dead 2) -
Confirm:How much projected textures should tint the water?
-
$waterdepth
<float>
(New with Counter-Strike: Global Offensive) - To do: What does this do exactly? Seems like it's related to $waterblendfactor, Found in liquids/nuke_water.vmt. Found in 2006/2007 code, does it do anything there?
-
$depth_feather
<integer>
(New with Counter-Strike: Global Offensive) - To do: What does this do exactly? Found in liquids/nuke_water.vmt.
Fog
-
$fogenable
<boolean>
- Enable volumetric fog for the water.
-
$fogcolor
<RGB matrix>
- Color of the water’s volumetric fog. Generally this value should match the color used in the bottom material.
-
$fogstart
<float>
- Distance in inches from the eye at which water fog starts.
-
Warning: Must be 0 for edge fading to work properly.
-
$fogend
<float>
- Distance in inches from the eye at which water fog ends.
-
$lightmapwaterfog
<boolean>
(New with Left 4 Dead 2) - Allows the fog to receive lightmaps, so that static objects can cast shadows onto the water. This must be enabled when the map is compiled.
Reflection
-
$reflecttexture
<texture>
- Texture to use for reflection. For real-time reflections, use
_rt_WaterReflection
. -
$reflectamount
<float>
- Amount of warp for the reflection. Higher values produce more visible reflections.
-
$reflecttint
<RGB matrix>
- Color tint for both expensive and cheap reflections.
-
$envmap
<env_cubemap / texture>
- See
$envmap
. Provides reflections for cheap water. -
Note:Don't use this on underwater materials.
-
$envmapframe
<integer>
- The frame to start an animated cubemap on.
-
$forceenvmap
<boolean>
(New with Portal 2) - Forces the water to use
$envmap
for reflections. -
$forcecheap
<boolean>
- Force the water to render itself as cheap, regardless of the map's
water_lod_control
entity settings or the user's settings. This will disable real-time reflection and instead use$envmap
. Refraction is assumed to be opaquely the water fog color. -
$forceexpensive
<boolean>
- Force the water to render itself as expensive, regardless of the map's
water_lod_control
entity settings or the user's settings. -
$cheapwaterstartdistance
<float>
- Distance from the eye in inches that the shader should start transitioning to a cheaper water shader.
-
$cheapwaterenddistance
<float>
- Distance from the eye in inches that the shader should finish transitioning to a cheaper water shader.
-
$reflectentities
<boolean>
- Make the water reflect entities. By default, no entities are reflected.
-
$reflectonlymarkedentities
<boolean>
(New with Portal 2) - Make the water reflect only entities and static props with "Render in Fast Reflections" enabled.
-
$reflectskyboxonly
<boolean>
(New with Left 4 Dead 2) - Make the water reflect only the skybox.
-
$reflect2dskybox
<boolean>
(New with Portal 2) - Make the water reflect the skybox material in addition to other reflections.
-
$reflect3dskybox
<boolean>
(Only in Counter-Strike: Global Offensive) - Make the water reflect the 3D skybox in addition to other reflections. Added in the Danger Zone update and used on dz_blacksite.
-
Note:Requires a
sky_camera
entity to be placed in the map, otherwise this might cause crashes. -
$reflectblendfactor
<float>
- To do: What does this do?
-
$nofresnel
<boolean>
(New with Half-Life 2: Episode One / Source 2006) - Disable the fresnel on the water's reflection.
-
Bug: Does not do anything in any engine branch.
-
$forcefresnel
<float>
(New with Alien Swarm) - Force this amount of fresnel on the water. Higher values usually cause the water to appear brighter.
-
$basereflectance
<float>
- To do: What is this?
-
$maxreflectance
<float>
- To do: What is this?
Refraction
-
$refract
<boolean>
(New with Left 4 Dead 2) - Whether the material should refract at all.
-
$refracttexture
<texture>
- Texture to use for refraction. For real-time refractions, use
_rt_WaterRefraction
. -
Tip:Specify
$refracttexture
without$reflecttexture
to get real-time refraction on$envmap
reflections. -
$refractamount
<float>
- Amount of warp for the refraction. Higher values produce more warping.
-
$refracttint
<RGB matrix>
- Color of the refraction.
-
Warning: It is recommended that you set this to white or something close to white so that edge transitions work properly on DX9.
-
$blurrefract
<boolean>
(New with Half-Life 2: Episode Two / Source 2007) (DX9+) - Blurs the refraction when underwater.
-
Warning: Underwater materials only; this will cause buggy behavior on any material with
$abovewater
set to 1. -
$pseudotranslucent
<boolean>
(New with Portal 2) - Make the water translucent. This is a cheap substitute for refractive water; do not use this when refraction is enabled.
-
$waterblendfactor
<normal>
(New with Portal 2) - How translucent the water should be when
$pseudotranslucent
is enabled. At 0, the water is completely transparent, while at 1 the water is completely opaque.
Flowing water
-
$scroll1 "[<normal X> <normal Y>]"
(New with Half-Life 2: Episode One / Source 2006) -
$scroll2 "[<normal X> <normal Y>]"
(New with Half-Life 2: Episode One / Source 2006) - If
$scroll1
is defined and X is not zero, two more instances of the normal map will be drawn in such a way that they are merged together. The first layer is 7x larger and rotated 45°; the second is 2x larger and rotated 90°. The parameters specify the speed and direction that the extra layers will move. (Valve's materials usually contain a third number, but it doesn't have any apparent effect and is most likely obsolete.)
Flow maps
-
$flowmap
<texture>
(New with Left 4 Dead 2) - Texture that defines flow velocity by skewing and scrolling the
$normalmap
. Valve generates their flowmaps with Houdini. - Video of the effect. For technical details, see Alex Vlachos' SIGGRAPH 2010 paper and Valve's GDC 2011 paper.
-
$flow_normaluvscale
<float>
(New with Left 4 Dead 2) - The number of world units covered by the normal map before it repeats. Typically in the 100s.
-
$flow_worlduvscale
<float>
(New with Left 4 Dead 2) - The number of times the flow map fits into the material. Face texture scale affects this.
-
$flow_uvscrolldistance
<float>
(New with Left 4 Dead 2) - How far along the flow map the normal map should be distorted. Higher values lead to more distortion.
-
$flow_timeintervalinseconds
<float>
(New with Left 4 Dead 2) - Time needed for the normal map to cross the
$flow_uvscrolldistance
. -
$flow_timescale
<float>
(New with Left 4 Dead 2) - Modifies flow speed without affecting the amount of distortion.
-
$flow_bumpstrength
<normal>
(New with Left 4 Dead 2) - How rough the surface of the water is.
-
$flow_noise_texture
<texture>
(New with Left 4 Dead 2) - A treatment texture used to break up repetition of the normal map.
-
$flow_noise_scale
<float>
(New with Left 4 Dead 2) - How many times to fit the noise texture into the normal map. Typically around 0.01.
-
$flow_debug
<boolean>
(New with Left 4 Dead 2) - Replaces the water surface with a literal rendering of the flow map.
Bug: Although the flow map will show up in Hammer, it may not be in the correct place! Don't rely on Hammer's view for alignment.
Basetexture Flow
-
$basetexture
<texture>
(New with Alien Swarm) - A "sludge layer", used in
for the sludge and debris in test chambers. The alpha channel of the
$basetexture
acts as a mask for the reflection; darker values are more reflective, while lighter values are less reflective. -
$color_flow_uvscale
<float>
(New with Alien Swarm) - The number of world units covered by the base texture before it repeats. Typically in the 100s.
-
$color_flow_timescale
<float>
(New with Alien Swarm) - Modifies flow speed without affecting the amount of distortion.
-
$color_flow_timeintervalinseconds
<float>
(New with Alien Swarm) - Time needed for the base texture to cross the
$color_flow_uvscrolldistance
. -
$color_flow_uvscrolldistance
<float>
(New with Alien Swarm) - How far along the flow map the base texture should be distorted. Higher values lead to more distortion.
-
$color_flow_lerpexp
<float>
(New with Alien Swarm) - How sharp the transition should be between repeats, should be 1.
- To do: Better explanation
-
$color_flow_displacebynormalstrength
<float>
(New with Portal 2) - How much the normal map affects the base texture. Uses extremely low values, usually 0.01 or less.
Authoring a flow map
Overall, trying to create a flow map manually is a nightmare. Painting the flow map, fitting it into the world, and painting foam, is extremely difficult.
But if you do want to give it a try, flow direction is read from the red and green channels of the flow map. 50% tone means no movement.
The texture scale of any faces using a water texture with a flow map appear to have a direct correlation on the flow map. The fewer water faces or planes you use the easier the process of authoring a custom flow map will be (selecting all of your water faces and using 'treat as one' when using the fit scaling may also be an option)
- There are now tools to assist in painting flowmaps.
- Flow field editor from algoholic.eu : http://algoholic.eu/another-flow-field-editor-update/
- Flowmap generator (paid): http://www.superpositiongames.com/products/flowmap-generator
- Creating flowmaps using Houdini (UDK) : https://www.dropbox.com/s/ii2x077vj64lyhl/Water%20Flow%20For%20UDK.pdf
Other
-
%compilewater
<boolean>
- This is needed to make a map using the material compile properly.
-
$surfaceprop
<water>
- Tells the physics system that the surface is water. See $surfaceprop.
-
%tooltexture
<texture>
- Defines the texture Hammer will display in the material browser.
-
WaterLOD proxy
- This connects the water_lod_control entity in a level to the water’s internal parameters. This must be declared in the material for the LOD mechanisms to work properly.
See also
- Adding Water (in Hammer)
- Creating a Waterfall Material
- Making a wall of water
- True reflections under CSS (French)