Sky (Source 1 shader)

Source Engine

Source 2

edit

Sky is a shader for materials in Source meant for 2D skyboxes. The old method of making skyboxes before Source 2007 involved using the UnlitGeneric shader with $ignorez 1. This shader expands the amount of usable parameters and also allows for HDR skyboxes.

Tip:(in all games since ) $basetexture is not necessary for games that are HDR-only, as only the $hdrbasetexture or $hdrcompressedtexture will be used.

Note:This shader always ignores fog. Skyboxes with UnlitGeneric (and without $nofog 1) are affected by fog.

Warning:The Counter-Strike 2 import script doesn't like $hdrcompressedtexture; change it to $basetexture, then decompress to  EXR with no_vtf and use that instead^[Clarify].

Warning:While rare, mat_fullbright set to 1 might sometimes break the rendering of this shader.

With an uncompressed HDR skybox texture

If the skybox texture uses uncompressed BGRA16f16f16f16f, then the VMT should look something like this:

sky
{
	$basetexture skybox/sky_wasteland_00up // Sky texture to use for LDR
	$hdrbasetexture skybox/sky_wasteland_00_hdrup // Uncompressed HDR Sky texture to use for HDR-enabled maps
	$nofog 1
	$ignorez 1
	$nomip 1
}
</source>

=== With a compressed HDR skybox texture ===
If the skybox has been [[Valve Texture Format#HDR compression|compressed using BGRA8888]], then [[$hdrcompressedtexture]] should be used instead:

<syntaxhighlight lang=php>
sky
{
	$basetexture skybox/sky_wasteland_00up // Sky texture to use for LDR
	$hdrcompressedtexture skybox/sky_wasteland_00_hdrup // Compressed HDR Sky texture to use for HDR-enabled maps
	$nofog 1
	$ignorez 1
	$nomip 1
}
</source>

{{todo|Figure out what the "HDR compression method B" mentioned in {{file|sky_hdr_dx9|cpp}} does differently, as it asks for $hdrcompressedtexture0, $hdrcompressedtexture1, and $hdrcompressedtexture2 instead of a single $hdrcompressedtexture.}}

=== Without an HDR skybox texture ===
If an HDR version of the skybox texture is not available, [[$hdrbasetexture]] can use the same VTF as [[$basetexture]]:

<syntaxhighlight lang=php>
sky
{
	$basetexture skybox/sky_wasteland_00up // Sky texture to use for LDR
	$hdrbasetexture skybox/sky_wasteland_00up // Sky texture to use for HDR, if the texture has NOT been specifically compiled for HDR
	$nofog 1
	$ignorez 1
	$nomip 1
}
</source>

=== Issues ===
{{cleanup|See [[HDR Skybox Creation]] for better explanation of when $basetexturetransform may be necessary.}}
You might find that skyboxes sometimes fit the entire projection area of a level. To re-scale the material to fit, use [[$basetexturetransform]] or add the following line:
<syntaxhighlight lang=php>
	$basetexturetransform "center 0 0 scale 1 2 rotate 0 translate 0 0" // For cutting off the bottom halves of the skybox

The scale 1 2 segment will maintain the fill-sizing of the X-axis, while locking the texture to the center line of the Y-axis (i.e. the absolute horizon line).