Cubemaps
A cubemap is a texture that represents a three-dimensional rendering of an area. The Source Engine uses env_cubemap entities as sampling points to generate these textures, which are then automatically embedded into the map file. Cubemaps, when built, are reflected on surfaces that use the $envmap parameter (with env_cubemap as its value).
Contents
Building cubemaps
Building cubemaps is the process of generating their textures to then use them as reflections. For technical reasons, this process is not automated and is up to the user to do so; until then, existing env_cubemaps will remain unused and the map, depending on the game, will display either generic or "missing" textures as reflections due to nonexistent cubemaps.
Warning: To build cubemaps, your game's screen resolution needs to be at least 4 times higher than the highest size of an existing env_cubemap, or else attempting to build them will either fail or even cause the game to crash. For example: if the highest env_cubemap sizes 128x128, a resolution of 512x512 will be needed. (128 × 4 = 512 -> 720x576 or higher)
Note: Newly-built cubemaps will display after relaunching the game.
Tip: Maxing out the game's visual settings before building cubemaps will generate their textures in the best-possible quality for the env_cubemaps' size.
Before building
Tip: Maps for 
Counter-Strike: Source and some other games are known for including pre-built, blank cubemaps after being compiled (even if there are no env_cubemaps in them). It is recommended to delete these cubemaps before building new ones, as explained here.
LDR
Note: This step does not apply to 
Counter-Strike: Global Offensive as its maps are compiled in HDR mode only.Building cubemaps on a map compiled in LDR (Low Dynamic Range) mode will generate textures only for that mode, regardless of your game's High Dynamic Range video setting. To build the cubemaps, submit the following commands into the game's console:
| Command | Description |
|---|---|
mat_specular 0 |
Disables reflections. Required to properly build cubemaps |
map cs_mymap |
Loads a map; replace "cs_mymap" with the map's actual name |
sv_cheats 1 |
Enables the use of cheat commands. Required to build cubemaps |
buildcubemaps |
Starts building cubemaps |
disconnect |
Unloads the map, returning you to the main menu |
mat_specular 1 |
Enables reflections |
quit |
(optional) Closes the game. Relaunching it is required to display newly-built cubemaps |
HDR
Building cubemaps on a map compiled with HDR support needs to be done twice - once for each mode (HDR and LDR). As opposed to a LDR map's case, your game's High Dynamic Range video setting has to be set to "Full" to build HDR cubemaps, and to "None" to build LDR ones. To build the cubemaps, submit the following commands into the game's console:
| Command | Description |
|---|---|
mat_specular 0 |
Disables reflections. Required to properly build cubemaps |
map cs_mymap |
Loads a map; replace "cs_mymap" with the map's actual name |
sv_cheats 1 |
Enables the use of cheat commands. Required to build cubemaps |
buildcubemaps |
Starts building cubemaps |
disconnect |
Unloads the map, returning you to the main menu |
sv_cheats 0 |
Disables cheat commands. Prevents command mat_reloadallmaterials from unnecessarily self-executing and briefly freezing the game
|
mat_hdr_level 0 |
Switches to LDR mode (from HDR); submit mat_hdr_level 2 instead if LDR cubemaps were built first
|
map cs_mymap |
Loads the map again to build cubemaps for the new mode |
sv_cheats 1 |
|
buildcubemaps |
Starts building cubemaps for the new mode |
disconnect |
|
mat_specular 1 |
Enables reflections |
mat_hdr_level 0/1/2 |
If necessary, switches back to the mode it was before having submitted mat_hdr_level 0/2
|
quit |
(optional) Closes the game. Relaunching it is required to display newly-built cubemaps |
Half-Life: Source
Bug: Building cubemaps in 
Half-Life: Source is currently not possible as their textures, despite being generated, aren't embedded into the map file afterward.
Workaround: Move the map file into the "maps" folder of a game of the same engine branch (such as 
Half-Life 2), build its cubemaps in that game, then move the file back into Half-Life: Source's folder.
Source Filmmaker
Bug: HDR cubemaps sizing lower than 64x64 built in 
Team Fortress 2 and some other games usually display graphical artifacts on reflections due to the last face of each cubemap not rendering properly in 
Source Filmmaker. While rebuilding cubemaps in it would normally fix the issue, it is currently not possible to do so as Source Filmmaker generates blank textures.- Workaround: If recompiling a special version of an affected map with env_cubemaps now sizing 64x64 is not an option, move the map file into
Alien Swarm's "maps" folder, build its cubemaps in that game, then move the file back into Source Filmmaker's folder.- Note: Alien Swarm's "gameinfo.txt" file needs to be edited for this procedure so that the game can have access to assets used by other games' maps not to build cubemaps with missing textures or models. The file's "SearchPaths" section should be like this:
"SearchPaths"
{
"Game" "|gameinfo_path|."
"Game" "swarm_base"
"Game" "platform"
"Game" "..\SourceFilmmaker\game\usermod"
"Game" "..\SourceFilmmaker\game\tf_movies"
"Game" "..\SourceFilmmaker\game\tf"
"Game" "..\SourceFilmmaker\game\hl2"
}
Note: Team Fortress 2 configurations were used for the example; consider replacing game subfolders (only those within Source Filmmaker paths) with the ones needed.Deleting cubemaps
Several tools make it possible to delete unnecessary or outdated cubemaps; of them all, BSPZIP not only is an official one, but is also the easiest and safest option for this procedure without potentially corrupting the map. To delete the cubemaps, execute the following command within the "maps" folder:
..\..\bin\bspzip -deletecubemaps mapname.bsp
Note: Replace "mapname" with the map's actual name. Warning: Deleting cubemaps actually deletes all the texture (".vtf") files embedded into the map at the time, so it's recommended not to embed custom textures before deleting cubemaps.Extracting cubemaps
In cases where a map has to be recompiled with minor changes and its built cubemaps vanish as a result, extracting them beforehand will make it not necessary to go through the whole cubemap-building process again until it actually becomes so. To extract its cubemaps with BSPZIP, create a folder that will contain the extracted cubemaps inside the "maps" one, then execute the following command:
..\..\bin\bspzip -extractcubemaps mapname.bsp "foldername"
Note: Replace "mapname" with the map's actual name, and "foldername" with the actual name of the folder to extract cubemaps into.
Embedding cubemaps
To make a map use extracted cubemaps, create a text file that will be used by BSPZIP - the file should be created inside the "maps" folder, and will contain paths to the files to embed into the map file. The file's content should be like this:
materials/maps/mapname/c-128_384_64.hdr.vtf foldername\materials\maps\mapname\c-128_384_64.hdr.vtf materials/maps/mapname/c-128_384_64.vtf foldername\materials\maps\mapname\c-128_384_64.vtf materials/maps/mapname/c448_-256_64.hdr.vtf foldername\materials\maps\mapname\c448_-256_64.hdr.vtf materials/maps/mapname/c448_-256_64.vtf foldername\materials\maps\mapname\c448_-256_64.vtf materials/maps/mapname/cubemapdefault.vtf foldername\materials\maps\mapname\cubemapdefault.vtf
Note: Replace "mapname" with the map's actual name, the cubemaps' filenames with correct ones, and "foldername" with the actual name of the folder that contains the extracted cubemaps.A file requires two dedicated lines (paths): the first line represents the path it will use within the map file, while the second one is the actual location of the file to embed into the map file. Relative location paths were used for the example, but they can also be absolute. Once the text file is ready, execute the following command:
..\..\bin\bspzip -addlist mapname.bsp textfile.txt newmapname.bsp
Note: Replace "mapname" with the map's actual name, "textfile" with the text file's actual name, and "newmapname" with either the map's actual name, or a new name not to overwrite the original file (and instead create a separate one).Renaming a map
Built cubemaps are saved into a folder within the map file that uses its name; renaming it will cause the cubemaps not to load alongside the map, and therefore it will act as if there were none. To fix that, either delete then rebuild the cubemaps, or extract then embed them back (with their folder's name matching that of the map).
