ColladaDOM 3

From COLLADA Public Wiki
Revision as of 21:46, 12 January 2017 by Mick P. (talk | contribs) (Forward to ColladaDOM 3 guide)
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search
Product information
  • Name: ColladaDOM 3 (COLLADA-DOM)
  • Purpose: XML Schema in modern C++
  • Last updated: January 8, 2017
  • Current version: 2.5.0
  • Status: non-Release/Preview-only
  • OS: Platform-Independent
  • Forum
  • Report bugs
  • Maintainer: Mick Pearson
  • Contact for technical issues:


This article is part of the COLLADA products directory
Adding to the list of products

The COLLADA Document Object Model (COLLADA DOM) is an application programming interface (API) that provides a C++ object representation of a COLLADA XML instance document. ColladaDOM 3 "rebrands" this label--stylizing it--in order to draw attention to the sharp contrast between it and previous versions of the library, starting with version 2.5.0.

The DOM was created by Sony Computer Entertainment America using a code generator directly from the COLLADA schema. The DOM is open source and available for download on Sourceforge. It has since been systematically reconstituted to a degree that bears little resemblance to the original code, but retains backward compatibility with it. This work was done in the public domain, for all. It is a good question as to whether or not the original copyright claims pertain still, but it is not of importance, and the library remains inspired by the workings of the original and indebted to and continually interested in its legacy.

A cyberspace manifesto in brief

This page is a one page user guide to the new library. It's hoped that one page suffices. But before getting into code examples, a short explanation of some of the terminology and predicaments entailed:

COLLADA was a valiant effort in the middle of the first decade of the new millennium. It failed to catch on. Its afterimage is in the form of various import and export plug-in utilities for various software. Whether or not it ever achieved in-house status as a pre/post-processing communication format anywhere is difficult to say, and if so, does it matter? Import/export support is limited, and fails to realize a fraction of what the manual imagines for COLLADA, and indeed anything of great use in real world terms.

Version 2.5 (ColladaDOM 3) tries to rectify this by placing an emphasis on lossless transformation and ease of use from the user's position, in order to better encourage and facilitate meaningful applications of COLLADA. It further expands the mission of COLLADA by imagining it as a future standard 3-D model format--a role that many take for granted, being unaware of subtle distinctions in terms of the designers original intent. It puts forward that this role, as a storage format, is more important in the coming years, especially as it concerns noncommercial applications.

The original choice to apply Wikipedia:XML Schema to COLLADA may have felt at the time as if it was an easing of a burden. Yet in retrospect, it actually establishes a very high bar for software development. Indeed, one that it is impractical to take lightly. For this reason, it seems as if developers could use a good amount of assistance. The new library approaches this in two ways: The first is simply to offer features that had been missing, which no XML document is complete without. This includes supporting externally defined XML schemas, as prescribed by the COLLADA manual and organization itself. The second is to use modern C++ idioms to form a maximally expressive grammar for writing algorithms against the "DOM." The remainder of this section focuses on this.

The C++ Standard Library has grown both in terms of concreteness and acceptance since the advent of the original COLLADA-DOM library. But also a "DOM" is a creature originally of HTML and incubated by JavaScript. To this end, the library leverages the "operator overloading" feature of C++ to produce a language neutral syntax for manipulating the "DOM" in code that is significantly more convenient than the standard library, and even JavaScript itself, but having more in common with high-level interpreted programming languages than the rigid strictures of the C++ Standard Library. And in addition to this there is an even greater need for a symbolic expressiveness that owes much to the need to reserve the use of language (identifiers) to the schemas themselves.

This quality of the new library is called "DAEP" or: Digital Artifact Excavation Protocol. It can alternatively use the less-neutral "digital asset exchange" (dae) language as originally established by COLLADA. It aims to establish an abstract/portable API, which COLLADA-DOM is but one implementation thereof. There also exists a twin API known as DAPP that is not part of COLLADA-DOM, where the P stands for Preservation. Its role is to convert old-world "digital artifacts" into capital D, capital A, "Digital Artifacts." DAEP is not a layer on top of COLLADA in so much as it merely brings the interface closer to working natively with an XML document in a "WYSIWYG" ethos. It trades the language of methods (function identifiers) with C++ operators, and informs free-form code--as one expects from operators.

Large schemas like COLLADA are hard to make sense of. The DAEP philosophy is to leverage code completion and comments alongside the strong-type correctness nurtured by C++ in order to bring work with such schema into reach. The reason this is required now is so to establish a long sought after all encompassing lingua franca for 3-D model data (digital artifacts) in order to prepare a path forward to a modern 3-D era that is to be seated firmly in the noncommercial sphere. This basic notion should be referred to as "cyberspace:" a term which has long been misapplied only to defy the ability to formulate a working model, or to relabel things which already exist and as such are of no import. COLLADA is the most obvious--but not the only--candidate vector for realizing such a space. To this end it must be a platonic space of works of art, and not a "place" as often conceived, like the WWW or Internet, not a landscape in new clothes, but rather a platonic space of digital artifacts.

This is a trajectory for COLLADA but by no means its only modern application. At this moment there is no noncommercial storage format if one is required. That is less grandiose than "cyberspace" but no less important, and in fact it is a natural predecessor to a cyberspace century. In order to speak meaningfully in this language there must be an ecosystem of applications wherein each must be able to faithfully transform the language, even if it cannot or does not need to comprehend it. If this basic end is not met then it is as if there is a legendary Tower of Babel where all is lost in translation. This is the first order of business. Secondary is supporting a feature-rich, multi-representational conception of COLLADA documents, that is more like the WWW than a tradition import/export framework; only that 3-D is a much taller order than the 2-D printed page. We must develop a more complete understanding of COLLADA and its analogues, so that we may appreciate the challenges we face ahead.

Only once all of this is accomplished is there reason at all to hammer out a new COLLADA-like standard. Without the software means, then what good is another standard? This is the more important work. This is the work of our day.

See also

External links

COLLADA DOM - Version 2.4 Historical Reference
List of main articles under the DOM portal.
User Guide chapters:  • Intro  • Architecture  • Setting up  • Working with documents  • Creating docs  • Importing docs  • Representing elements  • Working with elements  • Resolving URIs  • Resolving SIDs  • Using custom COLLADA data  • Integration templates  • Error handling

Systems:  • URI resolver  • Meta  • Load/save flow  • Runtime database  • Memory • StringRef  • Code generator
Additional information:  • What's new  • Backward compatibility  • Future work
Terminology categories:  • COLLADA  • DOM  • XML