Game Development Reference
In-Depth Information
9
A COLLADA Toolbox
Remi Arnaud
9.1 Introduction
COLLADA was first introduced during SIGGRAPH 2004 [Barnes and Arnaud 04]
as a digital asset exchange (.dae) specification. The effort to develop COLLADA
started in 2003, involving many companies such as Alias, Discreet, Digital Eclipse,
and Electronic Arts, and led to the publication of the version 1.4 specification as
an open standard by the Khronos Group [Khronos Group 11a], the same group
managing the OpenGL, OpenGL ES, WebGL, and other well-known graphics stan-
dard specifications. The 1.4 specification had minor fixes and updates, providing
the version 1.4.1 specification, which, at the time of this publication, is the most
popular implementation available.
During SIGGRAPH 2008, version 1.5 of the COLLADA specification was in-
troduced [Khronos Group 08], adding features from the CAD and GIS worlds such
as inverse kinematics (IK), boundary representations (B-Rep), geographic loca-
tion, and mathematical representation of constraints using MathML descriptive
language [W3C 94a]. Currently, the 1.4.x format is the format supported by most
applications, while 1.5 support is limited to applications in the computer-aided
design space. Versions 1.4.x and 1.5.x exist and are maintained in parallel. This
chapter uses version 1.4.1 of the specification, although everything is applicable to
either version of the specification.
Since COLLADA is an open standard, many software vendors have provided im-
plementations. COLLADA was designed from the start to be a lossless intermediate
language that applications can export and import. It is important to understand
that COLLADA is a language, and in order to be useful, a language needs to be
both spoken and understood. But as with every language, it is expected to be used
in slightly different ways and to evolve over time. The COLLADA specification
aims at formalizing how the COLLADA language can be used, and an application
that follows the specification to the letter should be able to cope with all those
variations, but in practice, implementations are limited by their underlying infras-
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