# Where to find the UsdLux Reference modified HdEmbree

**URL:** <https://forum.aousd.org/t/where-to-find-the-usdlux-reference-modified-hdembree/2663>\
**Category:** Hydra\
**Created:** [August 29, 2025, 2:49pm UTC](https://forum.aousd.org/t/where-to-find-the-usdlux-reference-modified-hdembree/2663 "2025-08-29T14:49:56Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![James](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.aousd.org/james/32/168_2.png) [@James](https://forum.aousd.org/u/James)\
**Post date:** [August 29, 2025, 2:49pm UTC](https://forum.aousd.org/t/where-to-find-the-usdlux-reference-modified-hdembree/2663/1 "2025-08-29T14:49:56Z")

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We were excited to hear and read the updates to UsdLux documentation and hdEmbree being used as a reference implementation for direct lighting behaviour.

However, when we built hdEmbree from OpenUSD 25.08 we noticed that it does not support UsdLux lights. Is there any build options/ environment variables we may be missing to enable this?  
[Universal Scene Description: UsdLux : USD Lighting Schema](https://openusd.org/release/api/usd_lux_page_front.html#usdLux_Behavior)

```auto
The example hdEmbree delegate provides a reference implementation, as well as a series of unit tests and reference images for renderers to check their own implementation against.

```

Thanks!  
James

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**Author:** ![nvmkuruc](https://avatars.discourse-cdn.com/v4/letter/n/76d3ee/32.png) [@nvmkuruc](https://forum.aousd.org/u/nvmkuruc)\
**Post date:** [August 29, 2025, 2:53pm UTC](https://forum.aousd.org/t/where-to-find-the-usdlux-reference-modified-hdembree/2663/2 "2025-08-29T14:53:57Z")

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Hi @James. The initial PR for the reference implementation just got merged into `dev`.

- [[hdEmbree] Initial UsdLux reference implementation (hdEmbree-UsdLux-PR06) by pmolodo · Pull Request #3186 · PixarAnimationStudios/OpenUSD](https://github.com/PixarAnimationStudios/OpenUSD/pull/3186)

You can track the status of the feature integrations here.

- [[hdEmbree] Add UsdLux support to hdEmbree, to make it a reference UsdLux implementation by pmolodo · Pull Request #3199 · PixarAnimationStudios/OpenUSD](https://github.com/PixarAnimationStudios/OpenUSD/pull/3199)

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<div class="post-metadata">

**Author:** ![James](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.aousd.org/james/32/168_2.png) [@James](https://forum.aousd.org/u/James)\
**Post date:** [August 29, 2025, 2:58pm UTC](https://forum.aousd.org/t/where-to-find-the-usdlux-reference-modified-hdembree/2663/3 "2025-08-29T14:58:29Z")

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Aha, great, happy to see I have not been imagining things! Will likely cherry pick some of those updates and give it a go!