Question:
What are the key features of Apple’s Out of this World?
Answer:
Out of this World from Apple is an extension to VRML based on the 3DMeta File (3DMF) format, used by Quick Draw 3D (QD3D), Apple’s cross-platform 3D graphics API.
QD3D is Apple’s API for presenting 3D on the desktop computer. An implementation of this API is currently available for the PowerMac and is due out for Windows but is not essential to using 3DMF. Apple’s aims in submitting their proposal are to provide developers with both stability and the flexibility needed for innovation. Stability they see as coming from the use of 3DMF as a foundation for all VRML, and innovation from 3DMF being an open standard with scope for extensions.
There are details in the proposal of how to handle behavior and this area is offered as a basis for discussion with the developer community. Essentially, scripts control behavior and its associated graphic elements. The scripts can be written in Java, but Apple believes a behavior language supported by a variety of scripting languages is the way to proceed. The Out of this World proposal is code-based rather than data-structure oriented; in this sense it resembles PostScript. It uses data to describe the starting state of the scene, and its objects and code to describe the dynamic interactions.
3DMF is described as a container file format which can contain 3D information on geometries( including lighting, textures, camera viewpoints, and shading), Web URLs, sound files, and other multimedia attributes.
Out of this World’s special features include:
- Use of binary file format which takes up less space, can be transmitted faster and parsed more easily than ASCII format.
- 3DMF text files are said to be 70% smaller than equivalent VRML 1.0 files and, in binary form, are smaller than even gzip compressed files.
- With no decompression to do, rendering can begin as soon as the file is received by the browser.
- Files can be easily parsed even when they include extensions to the basic format. Apple see parsing speed as being of increasingly great importance as desktop video, DVD-based Web content and high speed networks make greater demands on browsers.
- Out of this World has no need for Scene Graph architecture. This saves on memory use and the static route of data flow.
- The Out of this World browser is a script, downloaded with the scene; the script can be in Java or another scripting language. Therefore the browser is always dynamically up to date.
- Use of a non-centralized database of elements in the virtual world.
- Not dependent on any specific rendering technology.
- Uses the same file format on the desktop and on the Web.
- Allows any kind of data to be included in 3DMF as a new object type or attached as a custom attribute to existing objects. But only applications that understand the data type would be able to use the file’s contents.
- Backwards compatible with VRML 1.0 if a header and footer are added to encapsulate the old file in the new format.
- Although Out of this World does not explicitly enable multi-user interaction it does not obstruct it either.
According to Apple the light weight flexible structure of the format is suited to highly dynamic game-like interfaces, whereas Moving Worlds is suited to dynamic walkthrough experiences.
Availability: Source code, for all platforms, is available free with no license fee.
