View source for Deferred lighting

{{LanguageBar|title=Deferred lighting and Deferred shading}}
__NOTOC__
'''Deferred lighting''' is an alternate lighting technique and modification of '''[[WP:Deferred shading|deferred shading]]''', a screen-space shading technique that allows many lights to be rendered on the scene without significant performance hit.

It is much different from the default [[Radiosity]] lighting that comes with {{Src|4}}. It uses many different lighting passes to generate higher quality lighting, with real time shadows.

==Differences from vanilla radiosity==
When compiling a map in any of {{Valve|4|addtext='s}} games, each map is run through [[VRAD]], which takes data from all the light sources and compile them into a '''lightmap''' texture. While this does provide high-quality and variable lighting, it is completely static, save for the limited ability to toggle on some lights in a scene. The difference between [[radiosity]] and Deferred lighting is that Deferred lighting computes all its lights in real time. The game takes data from the normals of the object, its geometry, its albedo, and its specular lighting to create real time accurate lighting.

===Features===
*Quite cheap realtime lighting and shadows
*Almost infinite number of dynamic lights that can be active (stock [[Source]] only allows for one {{ent|env_projectedtexture}} at a time)
*High-fidelity [[Godrays]]
*[[Volumetric lighting]]
*Light cookies (premade shadow maps)

===Drawbacks===
*Traditional antialiasing like [[MSAA]] might not work with it like in {{bms|2}} (which was removed and replaced with FXAA because MSAA combined with deferred lighting caused certain models to have glowing outline around it),{{Cite|1}} but it depends how it was implemented into the game. As with {{asd|1}}, and {{lw|1}} is still supported, through it's recommended that you should use post-processing anti-aliasing method instead as they work best with deferred lighting, and has less performance hit.
*All lightmaps are disabled and only deferred lighting lights the world. {{only|{{asd}}}}
*Can be more taxing on older systems.
*DX9 or later only, older [[DirectX]] compatibility versions are not supported.

==Media==
[[File:Deferred phong ref.png|800px]]

==Availability==
Very few {{src|1|nt=1}} games utilize this lighting technique, as it is very complicated to implement, the games that do use this are listed here:
*{{apex|4}} (using Deferred shading)
*{{asd|4}} 
*{{lw|4}}
*{{p2d|4}}
*{{bms|4}}
*{{hammer|4}} (Lighting Preview in Stock HL2 and {{strata|4}})

==Tutorials==
* [[Implementing Deferred lighting into Source 2013]]

== See also ==
* {{asd|1}}
* [[Light editor]]
* [[Volumetric lighting]]
* {{ent|newLight_Point}}
* {{ent|newLight_Spot}}
* {{ent|light_deferred}}
* {{ent|light_deferred_global}}
* {{w|Deferred lighting}} (Wikipedia)

==External links==
* [https://learnopengl.com/Advanced-Lighting/Deferred-Shading Deferred Shading] on LearnOpenGL (basics)

{{references|1=
{{ref2|cite id=1|access-date=May 10, 2024|[https://store.steampowered.com/news/app/362890/view/4041374038285692283 Xen Technical Beta] and [https://steamcommunity.com/sharedfiles/filedetails/?id{{=}}1960023856 Screenshot by [TC<nowiki>]</nowiki>Ciaиєz ITA]:<br>
'''Known Issues - Haloing Around Props/Object'''<br>
'''MSAA''' is causing outlines around certain objects. MSSA is a performance killer and we hope to have a better solution for anti-aliasing with the Xen release. To remove the haloing/outline, simply turn off MSAA. }}
}}

[[Category:Graphics]]
[[Category:Shaders]]
[[Category:Glossary]]
[[Category:Technical]]