X3D and HTML5 Summary
Revision as of 08:35, 6 November 2009 by Brutzman (→Simple X3D and HTML5 examples: make link more obvious)
- 1 Family of X3D Specifications
- 2 X3D Strengths
- 3 Web3D Consortium has formal liaisons and working partnerships with other key organizations
- 4 Relationships between 3D scene graphs, APIs and render layers
- 5 Similarities between MathML, SVG, and X3D
- 6 X3D scene graph APIs
- 7 Differences with underlying render layers
- 8 Simple X3D and HTML5 examples
- 9 Lessons learned from years developing the FreeWrl X3D player
- 10 Action items for X3D and HTML5
- 11 Conclusions
Family of X3D Specifications
- X3D Abstract Specification describes basic functionality of how X3D works
- Three file formats are available: XML (.x3d), ClassicVRML (x3dv), and Compressed Binary Encoding (.x3db)
- 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
- International Organization for Standardization (ISO)
- World Wide Web Consortium (W3C)
- Open Geospatial Consortium (OGC)
- The Khronos Group
- Digital Imaging and Communications in Medicine (DICOM)
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?
- 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
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