X3D separates the scene, defined in ISO/IEC 19775-1, from the ways of writing it down, each a separate standard (ISO/IEC 19776). The Web3D Consortium publishes them. A scene has the same nodes, fields and routes in every encoding. This page follows the XML encoding (19776-1) and the ClassicVRML encoding (19776-2) of version 3.3; versions 3.0, 3.1, 3.2 and 4.0 use the same structure with their own version numbers.
The encodings
| Encoding | Extension | Media type | Starts with |
|---|---|---|---|
| XML | .x3d, gzipped .x3dz or .x3d.gz | model/x3d+xml | <?xml, then an X3D element |
| ClassicVRML | .x3dv, gzipped .x3dvz | model/x3d+vrml | #X3D V3.3 utf8 |
| Compressed binary | .x3db | model/x3d+fastinfoset | a Fast Infoset document |
The compressed binary encoding (19776-3) is the XML encoding written as Fast Infoset (ISO/IEC 24824-1), a binary form of XML, with special encoders for arrays of numbers and optional geometry compression. Its details are not described here.
Profiles, components and units
Every scene names a profile, the set of components a browser must support to show it, and may add further components at given levels.
| Profile | For |
|---|---|
Core | the minimum: metadata and the basics, for building on |
Interchange | exchanging geometry, appearance and simple animation between programs |
CADInterchange | CAD data |
Interactive | Interchange plus sensors and event utilities |
MedicalInterchange | medical volume data |
MPEG4Interactive | the subset used with MPEG-4 |
Immersive | roughly the capability of VRML97 |
Full | every component at its highest level |
A unit statement changes the base unit of a category for the whole
scene: angle (radians by default), force (newtons),
length (metres) or mass (kilograms), with a name and a
conversion factor to the default.
XML encoding
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE X3D PUBLIC "ISO//Web3D//DTD X3D 3.3//EN"
"http://www.web3d.org/specifications/x3d-3.3.dtd">
<X3D profile="Immersive" version="3.3">
<head>
<component name="Geospatial" level="1"/>
<unit category="length" name="feet" conversionFactor="0.3048"/>
<meta name="title" content="Example"/>
</head>
<Scene>
<Shape DEF="Ball">
<Sphere radius="0.5"/>
</Shape>
</Scene>
</X3D>| Element or attribute | Meaning |
|---|---|
X3D | the root, with profile and version; instead of the DOCTYPE, it may carry xmlns:xsd and xsd:noNamespaceSchemaLocation for schema validation |
head | optional: component (name, level), unit (category, name, conversionFactor) and meta (name, content) |
Scene | the one scene, holding the nodes |
| node element | a node; simple fields are attributes, node-valued fields are child elements |
containerField | which field of the parent a child node fills, when it is not the node’s usual one (for example proxy in Collision) |
DEF, USE | name a node, or reuse a named one; a USE element may only add containerField and class |
class | reserved for style sheets |
ROUTE | fromNode, fromField, toNode, toField |
ProtoDeclare | name; holds ProtoInterface (optional) of field elements and ProtoBody (required) |
field | name, type, accessType (inputOnly, outputOnly, initializeOnly, inputOutput), and a value attribute or child nodes |
IS, connect | inside a prototype body: connect has nodeField and protoField; IS must be a node’s first child (after any field or fieldValue) |
ExternProtoDeclare | name, nodeType, url (addresses ending # and the prototype’s name), and field elements |
ProtoInstance | name; fieldValue children (name, value) set initializeOnly and inputOutput fields |
IMPORT | inlineDEF, exportedDEF, AS |
EXPORT | localDEF, AS |
Attribute values use single or double quotes; spaces, tabs, line breaks and commas
separate numbers. Each string of an MFString is quoted inside the
attribute: url='"a.png" "b.png"'. Script and shader source goes in a
CDATA section after the field and IS elements.
ClassicVRML encoding
#X3D V3.3 utf8
PROFILE Immersive
COMPONENT Geospatial:1
UNIT length feet 0.3048
META "title" "Example"
DEF Ball Shape {
geometry Sphere { radius 0.5 }
}The syntax is VRML97’s (see VRML syntax) with these changes:
- The header line is
#X3D, the version andutf8. - One
PROFILEstatement must follow, then anyCOMPONENT name:level,UNIT category name factorandMETA "name" "content"statements, in that order. - Field access types are
inputOnly,outputOnly,initializeOnlyandinputOutput, in place ofeventIn,eventOut,fieldandexposedField. IMPORT inline.exported AS localandEXPORT local AS exportedshare nodes with anInline’s scene.#/*starts a block comment that ends at*/#.
Its keywords are AS, COMPONENT, DEF,
EXPORT, EXTERNPROTO, FALSE,
IMPORT, IS, META, NULL,
PROFILE, PROTO, ROUTE, TO,
TRUE, UNIT, USE, inputOnly,
outputOnly, inputOutput and initializeOnly.