Post

Building an X3D World

Posted Updated
By CREATE3000
4 min read
Building an X3D World

X3D file structure

X3D files contain:

  • The file header
  • Comments - notes to yourself
  • Nodes - nuggets of scene information
  • Fields - node attributes you can change
  • Values - attribute values
  • Routes - connections between fields
  • more …

A sample X3D file

XML Encoding

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE X3D PUBLIC "ISO//Web3D//DTD X3D 4.0/EN" "https://www.web3d.org/specifications/x3d-4.0.dtd">
<X3D profile='Interchange' version='4.0' xmlns:xsd='http://www.w3.org/2001/XMLSchema-instance' xsd:noNamespaceSchemaLocation='https://www.web3d.org/specifications/x3d-4.0.xsd'>
  <Scene>
  <!-- A Cylinder -->
  <Shape>
    <Appearance>
      <Material/>
    <Appearance>
    <Cylinder
        height='2.0'
        radius='1.5'/>
    </Shape>
  </Scene>
</X3D>

Classic VRML Encoding

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#X3D V4.0 utf8

PROFILE Interchange

# A Cylinder
Shape {
  appearance Appearance {
    material Material { }
  }
  geometry Cylinder {
    height 2.0
    radius 1.5
  }
}

Example

Cylinder

Understanding the header

#X3D V4.0 utf8

  • #X3D: File contains X3D text
  • V4.0 : Text conforms to version 4.0 syntax
  • utf8 : Text uses UTF8 character set

Understanding UTF8

  • utf8 is an international character set standard
  • utf8 stands for:
    • UCS (Universal Character Set) Transformation Format, 8-bit
    • Can encodes up to 2,164,864 characters for many languages
    • ASCII is a subset

Understanding profiles and components

  • PROFILE Interchange: File uses nodes from the Interchange profile
  • Nodes are grouped into components
  • Components are grouped into profiles
  • Browsers can load components on demand to reduce initial load times and improve performance by only fetching what is necessary when it’s needed
  • Additionally add as many COMPONENT statements you need

XML Encoding

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE X3D PUBLIC "ISO//Web3D//DTD X3D 4.0/EN" "https://www.web3d.org/specifications/x3d-4.0.dtd">
<X3D profile='Interchange' version='4.0' xmlns:xsd='http://www.w3.org/2001/XMLSchema-instance' xsd:noNamespaceSchemaLocation='https://www.web3d.org/specifications/x3d-4.0.xsd'>
  <head>
    <component name='CubeMapTexturing' level='3'/>
    <component name='Scripting' level='1'/>
  </head>
  <Scene>
    ...
  </Scene>
</X3D>

Classic VRML Encoding

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PROFILE Interchange

COMPONENT CubeMapTexturing : 3
COMPONENT Scripting : 1

What profiles and components are there:

Header statements

There are a few other header statements, but always add a PROFILE statement. If there is no profile declared, profile Full is assumed and all components will be loaded, but this is probably not always desired.

There are three header statements:

  1. COMPONENT statements
  2. UNIT statements
  3. META statements

Order of header statements is important!

XML Encoding

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<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE X3D PUBLIC "ISO//Web3D//DTD X3D 4.0//EN" "https://www.web3d.org/specifications/x3d-4.0.dtd">
<X3D profile='Interchange' version='4.0' xmlns:xsd='http://www.w3.org/2001/XMLSchema-instance' xsd:noNamespaceSchemaLocation='https://www.web3d.org/specifications/x3d-4.0.xsd'>
  <head>
    <component name='CubeMapTexturing' level='3'/>
    <component name='Scripting' level='1'/>
    <unit category='angle' name='degree' conversionFactor='0.017453292519943295'/>
    <unit category='length' name='millimetre' conversionFactor='0.001'/>
    <meta name='created' content='Thu, 08 May 2025 14:11:46 GMT'/>
    <meta name='modified' content='Thu, 08 May 2025 14:19:44 GMT'/>
  </head>
  <Scene>
    <!-- zero or more proto, node, route, import, export statements in arbitrary order -->
    ...
  </Scene>
</X3D>

Classic VRML Encoding

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#X3D V4.0 utf8

# exactly one profile statement
PROFILE Interchange

# zero or more component statements
COMPONENT Scripting : 1
COMPONENT CubeMapTexturing : 3

# zero or more unit statements
UNIT angle degree 0.017453292519943295
UNIT length millimetre 0.001

# zero or more meta statements
META "created" "Thu, 08 May 2025 14:11:46 GMT"
META "modified" "Thu, 08 May 2025 14:12:13 GMT"

# zero or more proto, node, route, import, export statements
# in arbitrary order
...

Using comments

XML Encoding

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<!-- A comment -->
  • Comments start with <!-- and must end with -->.

Classic VRML Encoding

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# A comment

#/* A
  * multi-line
  * comment */#
  • Comments start with a number-sign # and extend to the end of the line.
  • Mult-line comments start with #/* and must end with */#.

Using nodes

XML Encoding

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<Cylinder/>

Classic VRML Encoding

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Cylinder {
}
  • Nodes describe shapes, lights, sounds, etc.
  • Every node has:
    • A node type (Shape, Cylinder, etc.)
    • A pair of curly-braces
    • Zero or more fields inside the curly-braces

Using node type names

Node type names are case sensitive:

  • Each word starts with an upper-case character
  • The rest of the word is lower-case

Some examples:

Appearance, Cylinder, Material, Shape

Using fields and values

XML Encoding

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<Cylinder
    height='2.0'
    radius='1.5'/>

Classic VRML Encoding

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Cylinder {
  height 2.0
  radius 1.5
}
  • Fields describe node attributes

Every field has:

  • A field name (height, radius, etc.)
  • A data type (float, integer, etc.)
  • A default value
  • Different node types have different fields
  • Fields are optional
    • A default value is used if a field is not given
  • Fields can be listed in any order
    • The order doesn’t affect the node

Placing nodes

Every node has a »containerField« attribute with a default value, which is different for each node type. You can change the value if needed.

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<Collision>
  <Shape containerField='proxy'>
    <Box/>
  </Shape>
  <Transform>
    <!-- ... -->
  </Transform>
</Collision>

Summary

  • The file header gives the version and encoding
  • Nodes describe scene content
  • Fields and values specify node attributes
  • containerField attribute can be changed.
  • Everything is case sensitive
Tutorials
Building World
This post is licensed under CC BY 4.0 by the author.

Shapes, Geometry, and Appearance