Overview#

The omni.hydra.scene_delegate extension provides a high-performance Hydra scene delegate implementation that accelerates USD scene rendering by bypassing traditional Hydra/USD bottlenecks. This extension creates a fast-path data flow from USD scene changes directly to render delegates, enabling real-time performance for large, dynamic scenes.

Fast Scene Delegate Architecture#

The extension implements two complementary scene delegates that work together: a traditional UsdImagingDelegate for compatibility and a specialized OmniHydraDelegate for performance. The OmniHydraDelegate serves as a fast-path alternative that maintains its own optimized cache of scene data, allowing it to respond to scene queries without the overhead of traditional USD attribute resolution. This dual-delegate approach ensures both performance and compatibility across different rendering scenarios.

The extension also supports fetching a subset of rendering data (transforms, lights, etc.) from Fabric. It pulls scene data directly from Fabric ring buffers at render time, allowing systems like physics and OmniGraph to push updated transforms, deformations, and other animated properties that get sampled at precise frame times. This ring buffer integration allows the delegate to access pre-computed interpolated values for any time sample efficiently.