USDKit
Author, compose, and manipulate Universal Scene Description content from Swift.
Overview
USDKit is the Swift API for authoring, composing, and manipulating Universal Scene Description (USD) content. USD is an open scene-interchange format originated by Pixar and now stewarded by the Alliance for OpenUSD; it represents 3D scenes, assets, and animations across digital-content-creation tools and runtime engines. USDKit exposes a curated subset of OpenUSD through a hand-written, ABI-stable Swift surface.
The framework centers on three core types. A USDLayer represents a single USD document — either a file on disk or an anonymous in-memory document — and serves as the unit of scene description. A USDStage assembles a hierarchy from one or more layers by applying USD’s composition rules to a root layer, producing the runtime view of a scene. Each node in that hierarchy is a USDPrim, which carries a path, attributes, relationships, references, and child primitives. Because multiple layers can define or override the same primitive, the stage composes the contributions from each layer to produce the final scene.
Typical work in USDKit includes generating USD documents procedurally, extracting information from existing assets, applying bulk transformations across composed scenes, and building editors or pipeline tools. The framework also provides the supporting types that authoring depends on — type-erased value containers, interned string tokens, and transform operations — along with a RealityKit integration layer for rendering and playing composed scenes inside an entity hierarchy.