# Deprecating Hydra 1, eventually

**URL:** <https://forum.aousd.org/t/deprecating-hydra-1-eventually/2804>\
**Category:** Announcements\
**Created:** [December 23, 2025, 6:10pm UTC](https://forum.aousd.org/t/deprecating-hydra-1-eventually/2804 "2025-12-23T18:10:24Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![blevin](https://avatars.discourse-cdn.com/v4/letter/b/ed655f/32.png) [@blevin](https://forum.aousd.org/u/blevin)\
**Post date:** [December 23, 2025, 6:10pm UTC](https://forum.aousd.org/t/deprecating-hydra-1-eventually/2804/1 "2025-12-23T18:10:24Z")

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Starting with OpenUSD release 25.11, the Hydra UsdImaging scene index codepath for UsdImagingGL is enabled by default. This represents a significant step in Hydra 2’s maturity and readiness after years of development.

All development efforts are focused on the Hydra 2 codepaths and our studio is relying on it for our active production. We encourage everyone to move towards the scene index API’s and report any regressions they encounter.

For backwards compatibility or diagnostics, scene delegate mode can be restored by setting the environment variable `USDIMAGINGGL_ENGINE_ENABLE_SCENE_INDEX` to 0.

As a step towards gradual deprecation of Hydra 1, we intend that the next OpenUSD release 26.03 will issue a deprecation notice at runtime when the scene delegate code path is used. Subsequently, we intend that some future release – yet to be decided – will begin to remove scene delegate support altogether.

Please let us know if you have any questions or concerns.

–  
Team Hydra

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**Author:** ![shaegler](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.aousd.org/shaegler/32/90_2.png) [@shaegler](https://forum.aousd.org/u/shaegler)\
**Post date:** [December 23, 2025, 6:18pm UTC](https://forum.aousd.org/t/deprecating-hydra-1-eventually/2804/2 "2025-12-23T18:18:38Z")

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FWIW & FYI, the Adobe file format plugins (current main branch) require `USDIMAGINGGL_ENGINE_ENABLE_SCENE_INDEX=0`, otherwise no textures are shown in usdview.

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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:** [January 8, 2026, 3:27pm UTC](https://forum.aousd.org/t/deprecating-hydra-1-eventually/2804/3 "2026-01-08T15:27:27Z")

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Hi @blevin.

Will there be a way to silence the deprecation notice?

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**Author:** ![blevin](https://avatars.discourse-cdn.com/v4/letter/b/ed655f/32.png) [@blevin](https://forum.aousd.org/u/blevin)\
**Post date:** [January 24, 2026, 12:49am UTC](https://forum.aousd.org/t/deprecating-hydra-1-eventually/2804/4 "2026-01-24T00:49:27Z")

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Hi @mkuruc – sure thing, we’ll add a `USDIMAGINGGL_ENGINE_ENABLE_SCENE_INDEX_DEPRECATION_WARNING` to opt out of the deprecation warning (i.e. by setting it to 0).

-B

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**Author:** ![blevin](https://avatars.discourse-cdn.com/v4/letter/b/ed655f/32.png) [@blevin](https://forum.aousd.org/u/blevin)\
**Post date:** [October 17, 2026, 11:56pm UTC](https://forum.aousd.org/t/deprecating-hydra-1-eventually/2804/5 "2026-10-17T23:56:04Z")

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An update on this. We expect the upcoming OpenUSD release 26.11 to be the last release still supporting USDIMAGINGGL\_ENGINE\_ENABLE\_SCENE\_INDEX=0. This env setting will be removed in the subsequent release (27.02).

Note that this only affects usdImagingGL. The underlying Hydra 1 UsdImagingDelegate in usdImaging remains available for now, but we encourage clients to switch over to the UsdImaging Hydra 2 scene index equivalent.

thanks,  
Team Hydra