H3D API Training Part 2.1: X3D

Outline  Scene graphs  X3D – XML syntax  X3D components overview

Scene Graph Group Transform Shape Box Shape Sphere“gold” children appearance geometry

Scene Graph  The scene graph is a directed graph of nodes used to define and manage applications  Hierarchical structure – children/parent. Each node affects its children.

What is a Node? ◦ A container for fields: ◦ Manages fields  Allocation, deallocation of fields  Initialisation of fields  Manages internal (and external) routes ◦ Reusable modules of functionality ◦ Simplify application development

Nodes

X3D  ISO standard for 3D content and interaction  Backwards compatible with VRML 

X3D - XML  “XML encoding” of X3D  Similar in appearance to HTML (technically a subset of XML)  Basic structure: ◦ Header ◦ Statements (scene graph nodes, routes)

Example

XML  Objects encoded begin with a “<name” and end with either ◦ “/>” for single entities ◦ “ ” for compound entities

Comments  Comments are enclosed within

X3D – DEF/USE

X3D – DEF/USE example  Reference an existing DEFined Node with the USE attribute  Useful to avoid data duplication / redundancy ◦ Especially with appearances ◦ Any mesh geometry that is identical

X3D - ROUTE  Dependencies between field are set up with routes:

Example DEF/USE/ROUTE

X3D - containerField  Indicates the default field that a node should be assigned to ◦ e.g. “child” for Group, Transform, Shape ◦ “appearance” for Appearance ◦ “geometry” for IndexedFaceSet, Sphere  containerField hidden from most X3D and H3D use, but necessary to know about

X3D Components

Grouping Component  Group ◦ Basic grouping.  Transform ◦ Specifies coordinate system transformation.  Switch ◦ Choose one of many children.

Geometry Component  Shape  Appearance  Geometry ◦ Box ◦ Cone ◦ Sphere ◦ IndexedFaceSet ◦ etc

Texturing Component  ImageTexture ◦ MultiTexture ◦ PixelTexture ◦ (MovieTexture)  TextureTransform  TextureCoordinate

Interpolator Component  Useful for basic animations: ◦ ColorInterpolator ◦ CoordinateInterpolator ◦ NormalInterpolator ◦ OrientationInterpolator ◦ PositionInterpolator

Text Component  Text  FontStyle

Lighting Component  DirectionalLight  PointLight  SpotLight

Other Components  Time  RigidBodyPhysics  Rendering  Sound  Device Sensors  Navigation  Programmable shaders  Particle system

X3D Abstract Nodes  X3D specification defines abstract nodes; ◦ Cannot be instantiated / used ◦ Contain common functionality used in certain types of nodes ◦ Nodes inherit from abstract nodes

X3D Abstract Nodes  All X3D abstract nodes begin with “x3d” ◦ X3DNode ◦ X3DChildNode ◦ X3DGroupingNode ◦ X3DGeometryNode ◦ X3DLightNode ◦ etc

Interface objects  X3D specifies a number of abstract interfaces.  Specifies some functionality that a node should implement.  Examples: X3DBoundedObject X3DUrlObject H3DDisplayListObject

H3DLoad and H3DViewer  Settings via H3DLoadSettings program  H3DLoad – console  H3DViewer – window application ◦ Settings for changing different options on the fly.