Deprecating Hydra 1, eventually

General Announcements
1

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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2

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

3

Hi @blevin.

Will there be a way to silence the deprecation notice?

4

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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