A Prim refers to a fundamental building block or element of a scene within the USD framework. Prim is short for “primitive,” and it represents an individual object or entity within the scene hierarchy.
A USD prim can be thought of as a container that holds various types of data, attributes, and relationships. It represents a specific object or component in a scene, such as a model, camera, light, or even a group of other prims. Prims are organized in a hierarchical structure, forming a scene graph that represents the relationships and transformations between objects in the scene.
Each prim in USD has a unique identifier, known as a path, which identifies its location within the scene graph. The path typically includes the names of all the parent prims leading to the specific prim. For example, a prim’s path might be “/World/Characters/CharacterA,” indicating that it is a child of the “CharacterA” prim, which itself is a child of the “Characters” prim, and so on.
Prims can have various types of attributes associated with them, such as position, rotation, scale, material information, animation data, and more. These attributes define the properties and characteristics of the objects they represent.
One of the key features of USD prims is their ability to encapsulate data and relationships within a single object. This encapsulation allows prims to be shared, referenced, and instanced across different scenes and files. It enables efficient data management, promotes modularity, and facilitates collaborative workflows.
In summary, a USD prim represents an individual object or component within a scene in the Universal Scene Description framework. It serves as a container for data, attributes, and relationships, forming a part of the scene graph. Prims are organized hierarchically, have unique paths, and allow for efficient encapsulation and sharing of data within the OpenUSD ecosystem.