X3D and HTML5 Summary

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Status: these are draft slides for the X3D and HTML5 working-group effort that will be provided to the Technical Plenary Week (TPAC) 2009.

  • Family of X3D Specifications
    • X3D Abstract Specification describes basic functionality
    • Three file formats are available: XML (.x3d), ClassicVRML (x3dv), and Compressed Binary Encoding (.x3db)
    • High-performance Application Programming Interfaces (APIs) are defined for Ecmascript (Javascript) and Java

  • X3D Strengths
    • Non-profit Web3D Consortium maintains and extends X3D via working groups
    • Set of International Standards certified over 12-year period by multiple national bodies in ISO
    • Multiple implementations are available (open and commercial source)
    • Numerous resources available online, including specifications themselves
    • Third-generation 3D graphics language that extends predecessor Virtual Reality Modeling Language (VRML97)
    • Long-time W3C member and contributor

  • Relationships between 3D scene graphs, APIs and render layers
    • Scene graphs are high-level declarative models about how geometry is constructed, colored and animated; these can be expressed as an XML tree
    • APIs are mid-level libraries for programmers to create imperative source code about geometry and animation (various proprietary codebases, perhaps WebGL or O3D)
    • Render layers are low-level software libraries that expose the functionality of graphics hardware (e.g. OpenGL and DirectX)
    • Numerous other 3D technologies exist at each of the other layers, often in the form of codebases
    • The X3D Specifications include both declarative models and strongly typed APIs

  • Similarities between MathML, SVG, and X3D
    • MathML describes mathematical expressions and then renders a presentation of them
    • Scalable Vector Graphics (SVG) describes and presents renderings of 2D shapes, with optional animation and interaction
    • Extensible 3D (X3D) describes and presents renderings of 3D shapes, with optional animation and interaction
    • All three languages are formally specified and have well-developed XML encodings
    • Authors want to use these languages for multimedia content in HTML pages

  • X3D scene graph APIs
    • X3D Scene Access Interface (SAI) provides a consistent standardized high-performance API
    • X3D SAI has Ecmascript and Java bindings, other programming languages can be added
    • X3D SAI is functionally equivalent and has same expressive power as file formats
    • Document Object Model (DOM) is also legal (X3D is XML after all) but infrequently used because of low performance

  • Differences with underlying render layers
    • OpenGL, DirectX, others are used as render layers for output of X3D player which parses .x3d XML files and draws them
    • Unlikely that all browsers will implement the same render layer (OpenGL ≠ DirectX)
    • A Canvas3D layer might be helpful to unify calls to the underlying render layer - but how will it evolve over time?
    • Not clear that Web authors are clamoring for ability to program low-level OpenGl (or similar) source code in Javascript, such models are not interoperable or composable
    • X3D avoids these problems as a declarative scene-graph language available in XML

  • Simple X3D and HTML5 examples
    • X3D scene as external reference (Anchor link)
    • X3D embedded in object tag
    • HTML5 with embedded X3D as mixed-namespace document
    • Forthcoming InstantReality X3DOM javascript demo: html5+x3d with event-passing connections
    • (Can we structure our non-scripted examples to correspond to MathML and SVG examples?)

  • Action items for X3D and HTML5
    • Ensure proper X3D references in HTML5 specifications - what happened?
    • Continue to document correct integration and best practices for X3D and HTML5
    • Continue to watch the relationship between HTML5 and XHTML