1. Overview

This specification defines version 1.0 of the calino file format. The calino format is a carefully designed file format intended for the storage and delivery of texture data for realtime 3D rendering applications.

This specification is divided into an abstract model and a separate binary encoding. The purpose of the model is to describe the semantics of calino files; the actual meaning of the data within, and to describe properties and invariants that must be true for all valid calino files. The purpose of the binary encoding is to describe how the model is transformed to a sequence of bytes/octets; it describes the low-level on-disk format of calino files. This layered approach is intended to allow for specifying the format with a level of precision that will allow data in the calino format to remain readable for decades into the future, and in a manner that ensures that the format is not dependent on any present-day rendering APIs.

Developers wishing to write their own code to read and write calino files might find it easiest to view the binary encoding section first. The calino format is designed to be straightforward to parse, requiring only a few minimal primitives to express the entirety of the format, and requires no references to external specifications (unlike many other image/texture file formats) [1]. Once a developer is able to read data from an existing calino file, they should consult the model to understand what the data they're receiving actually means. The model chapters are arranged in dependency order starting with the most fundamental concepts, and ending with the top level definitions of the various texture types.