View source for Sky (Source 1 shader)

{{tabsBar|main=Sky (shader)}}
'''Sky''' is a shader for materials in [[Source]] meant for [[Skybox_(2D)|2D skyboxes]]. The old method of making skyboxes before [[Source 2007]] involved using the [[UnlitGeneric]] shader with <code>[[$ignorez|$ignorez 1]]</code>. This shader expands the amount of usable parameters and also allows for [[HDR]] skyboxes.
{{tip|{{l4d2|since}} [[$basetexture]] is not necessary for games that are HDR-only, as only the [[$hdrbasetexture]] or [[$hdrcompressedtexture]] will be used.}}
{{warning|The {{cs2|2}} import script doesn't like {{code|$hdrcompressedtexture}}; change it to {{code|$basetexture}}, then decompress to {{w|OpenEXR|EXR}} with {{no_vtf|3.1}} 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 [[Valve Texture Format#Image_data_formats|uncompressed BGRA16f16f16f16f]], then the [[VMT]] should look something like this:

<source lang=php>
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:

<source 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]]:

<source 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:
<source lang=php>
	$basetexturetransform "center 0 0 scale 1 2 rotate 0 translate 0 0" // For cutting off the bottom halves of the skybox
</source>

The <code>scale 1 2</code> 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).

[[Category:Shaders]]