View source for $ambientocclusion

{{Source topicon}}{{SFM topicon}}
[[File:valveao.jpg|thumb|200px|Various WrinkleMaps maps found in Valve games for eyes and face.]]

'''Ambient occlusion''' is a shading method which helps add realism to local reflection models by taking into account attenuation of light due to occlusion {{clarify}}. Unlike local methods like [[Phong materials|Phong shading]], ambient occlusion is a global method, meaning the illumination at each point is a function of other geometry in the scene. However, it is a very crude approximation to full global illumination. The soft appearance achieved by ambient occlusion alone is similar to the way an object appears on an overcast day. It is globally supported on the [[EyeRefract]] shader. The [[Source Filmmaker|IFM]] module, when loaded, makes the '''<code>$ambientocclusion</code>''' parameter function on other shaders such as [[VertexLitGeneric]] as a means of controlling the intensity of [[Screen Space Ambient Occlusion (SSAO)|SSAO]].
{{ClassicConfirm|Does this just apply to the IFM version or the current release of [[Source Filmmaker|Source Filmaker]]? }}

{{TODO|How does using a dedicated ambient occlusion texture differ from just baking it into the base texture (and possibly also the phong/specular mask)?}}

{{Bug|When used on transparent materials (either <code>[[$translucent]]</code> or <code>[[$alphatest]]</code>, or all materials on a model where a transparent material has been used without compiling with either <code>$Opaque</code> or <code>$MostlyOpaque</code> in the QC file), <code>$ambientocclusion</code> also causes the material to render the effect for any objects behind the material. ''(Tested in Source Filmmaker)''}}

==Using Ambient Occlusion==
===Example VMT Syntax===
The following example is taken from [[Left 4 Dead]] from the model material located in <code>L4D root/materials/models/survivors/teenangst/teenangst_eyeball_l.vmt</code>

{{CodeBlock|lines=18|src=teenangst_eyeball_l.vmt|[[EyeRefract]]<nowiki>
{
	$Iris "models/survivors/green_iris2" 
	$AmbientOcclTexture "models/survivors/survivor_eye_ao" 
	$Envmap "Engine/eye-reflection-cubemap-" 
	$CorneaTexture "Engine/eye-cornea" 
	$EyeballRadius "0.6" 
	$AmbientOcclColor "[.4 .4 .4]" Default 0.33, 0.33, 0.33
	$Dilation ".5" 
	$ParallaxStrength "0.25" 
	$CorneaBumpStrength ".5" 
	$halflambert 1
	$nodecal 1
	$ambientocclusion 1
	
	$RaytraceSphere 1 
	$SphereTexkillCombo 0 
}</nowiki>}}

===VMT Parameters===
;<code>$AmbientOcclusion <[[float]]></code> 
: Controls strength of Ambient Occlusion. (1 = fully enabled, 0 = fully disabled)
{{note|Used to control the strength of the SSAO for models in Source Filmmaker.}}
;<code>$AmbientOcclColor "[.n .n .n]"</code> 
: Replacing n with a number of the color (RGB format)
;<code>$AmbientOcclTexture "path/to/vtf"</code> 
: Filename of the ambient occlusion texture to use
{{TODO|How does <code>$ambientocclusiontexture</code> fit in with all of this?}}

== See also ==

* [[Phong materials|Phong Materials]]
* [[$phong]]
* [[$basetexture]]
* [[$envmapmask]] (specular mask)
* [[$envmap]] (environment map)
* [[$selfillum]]

[[Category:Shader parameters|a]]
[[Category:VMT Lighting]]