The RenderMan Interface - Paul Bourke

Appendix D
RENDERMAN INTERFACE BYTESTREAM
CONVENTIONS
Version 1.1
File structuring conventions for RIB files are presented to facilitate the use of RIB as a file
format for rendering interchange. A format for single User Entities is presented to allow
importing external models into existing RIB streams. Finally, we describe a rendering services
file format that will enable Render Managers to provide services to a specific renderer.
D.1 RIB File Structuring Conventions
The RenderMan Interface Bytestream (RIB) is a complete specification of the required interface
between modelers and renderers. In a distributed modeling and rendering environment
RIB serves well as a rendering file format. As RIB files are passed from one site to
another, utilities for shader management, scene editing, and rendering job dispatching (referred
to hereafter as Render Managers) can benefit from additional information not strictly
required by rendering programs. Additional information relating to User Entities, resource
requirements and accounting can be embedded in the RIB file by a modeler through the
“proper” use of RIB in conjunction with some simple file structuring conventions.
This section lays out a set of RIB file format conventions which are patterned loosely after
the model put forth in Adobe’s “Document Structuring Conventions.”
D.1.1
Conforming files
The conventions outlined in this section are optional in the sense that they are not interpreted
by a renderer and thus will not have any effect on the image produced. Although
a Render Manager may require conformance to these conventions, it may choose to utilize
or ignore any subset of the structural information present in the RIB file. A RIB file
is said to be conforming if it observes the Pixar RIB File Structuring Conventions, and the
conforming file can be expected to adhere to specific structuring constraints in that case.
185