X3D and HTML5 Summary

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Status: these are the X3D and HTML5 working-group slides presented to the HTML Working Group during Technical Plenary Week (TPAC) 2009. These slides are also available in .pdf form.

Family of X3D Specifications

  • X3D Abstract Specification describes basic functionality of how X3D works
  • Three file formats are available
    • XML (.x3d) with XML Schema and also DTD
    • ClassicVRML (x3dv)
    • Compressed Binary Encoding (.x3db) with geometric compression and Fast Infoset (FI)
  • High-performance Application Programming Interfaces (APIs) are defined for Ecmascript-264 (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

Web3D Consortium has formal liaisons and working partnerships with other key organizations

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 these 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 functionally consistent standardized high-performance APIs
  • 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 (.x3d, .x3dv, .x3db)
  • Document Object Model (DOM) is also legal (X3D is XML after all) but historically has been 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

Detailed example source is provided on the X3D and HTML5 examples page.

  • X3D scene as external reference (Anchor link)
  HTML source:  Here is my <a href='HelloWorld.x3d' title='Link to new X3D document'>HelloWorld example</a> in X3D.
  • X3D embedded in object tag
  HTML Object Tag for X3D shows how to place X3D objects within an HTML page
  • HTML5 with embedded X3D as mixed-namespace document
  X3Dom demonstration

X3DOM.org implementation

  • Open Source, Javascript / WebGL based
  • Needs Firefox/WebKit nightly builds
  • Runs without any plugin
  • Can be easily modified while evolving
  • Needs XHTML encoded data, one line script per XHTML

X3DOM.org functionality

  • Searches for existing <X3D xmlns= > and creates scenegraph from DOM Tree
  • Creates canvas with WebGL-Context for rendering
  • Monitors changes with DOM Level 2 events (DOMNodeRemoved, DOMNodeInserted, DOMAttrModified)
    • DOMAttrModified buggy in WebKit !!!
  • Supports simple interaction (HTML events on 3D Object) and navigation

X3DOM.org status

  • 3 work-months of development
  • Manageable Code Size (~5000 Lines JavaScript Code, ~1000 Lines GLSL Shader Code)
  • Support well defined Subset of X3D
    • Interchange Profile + Inline, Scripting, Text nodes
    • No Scripting or Prototype on the X3D side
  • Dynamic X3D content
    • Support for n:m FieldToField ROUTEs, TimeSensor + Interpolator + Follower nodes

X3DOM.org solution considerations

  • Provides an experimental open-source runtime – not the ultimate solution
    • Feature Limitations: e.g. no access to spatial audio or video texture layer
    • Performance Limitation: Javascript/WebGL can only handle models up to ~200.000 Triangle right now
  • Standardization and native implementations are needed
    • Support for SAI/X3D-Plugin in addition to the WebGL-Render backend will be next iteration
    • Final deployment solution best as part of browser
    • X3D community has multiple open-source C/C++ codebase resources available

Lessons learned from years developing the FreeWrl X3D player

  • Experience: FreeWRL was originally interpreted Perl with specialized "C" functions. Hoped that hardware would improve faster than size of models; that was not the case.
  • Interpreted was not the way to go, rewritten in C for performance
  • Differing OpenGL capabilities: X3D Browsers can handle these, so older models can run efficiently on new hardware (write once, run anytime; even VRML1 models from NASA run fast now)
  • X3D models are not tied to specific hardware, can run over OpenGL-ES, OpenGL-3.2, DirectX11, older standards like OpenGL-1.0...
  • OpenGL requires significant programming skills. Don't know why the average web author would want to code in OpenGL.
  • What does FreeWRL require from Web browser or window? An OpenGL Context (i.e. a number); mouse and keyboard events, window size events, that's about it.

Action items for X3D and HTML5

  • Ensure proper X3D references in HTML5 specifications - what happened, what happens next?
  • How to allow X3D scene to either reserve screen space or float over the page? Presumably CSS, X3D elements include the class attribute
  • X3D version 3.3 draft is considering SVG and HTML as source for image textures; how to pass events?
  • X3D compression will likely evolve to use Efficient XML Interchange (EXI)
  • Web Accessibility is a future interest
  • Continue to document correct integration and best practices for X3D and HTML5


  • X3D Graphics is a natural fit for HTML5
  • We want to maximize capabilities and deployment
  • Further collaboration welcome