KHR_lights_area: Proposal

[maggieholbling]

Could a rectangle type be added to the KHR_lights_punctual extension? Seeing as Unity, Unreal and Blender support rectangular area lights?

Unity: https://docs.unity3d.com/Manual/Lighting.html
Unreal: https://docs.unrealengine.com/en-US/BuildingWorlds/LightingAndShadows/LightTypes/RectLights/index.html
Blender: https://docs.blender.org/manual/en/latest/render/lights/light_object.html

If not, is there a workaround around this?

[donmccurdy]

Related: #1475

KHR_lights_punctual is feature-complete, for the purposes of the glTF 2.0 specification, and restricted to simpler punctual lighting. But area lights could be considered as part of a future extension. Understanding which properties of area lights already have consistency across engines and authoring tools (Blender/Maya/3DS Max) might help that process, if anyone would like to research it.

[MiiBond]

@maggieholbling, Adobe would definitely be interested in supporting an area light extension. I'll be looking at defining one later this year, I think, as we'll have need of it. If you want to get the ball rolling by writing a draft EXT (multi-vendor) extension, I can take a peek and give feedback.

[romainguy]

@MiiBond I would love to see an area light extension as well (definitely rectangle and line lights at least).

@maggieholbling This extension would not be the right place since rectangular lights are by definition not punctual lights.

[donmccurdy]

I'll rename this issue as a proposal for KHR_lights_area. 👍

[UX3D-nopper]

Could we close this and/or continue the discussion here:
#1948