In VRML 1.0, you just place children nodes inside the parent node. Like this:

#VRML V1.0 ascii

Group {
  Sphere { }
  Cube { width 1.5 height 1.5 depth 1.5 }
}

Figure 1.5. A cube and a sphere in VRML 1.0

Group is the simplest grouping node. It has no fields, and it's only purpose is just to treat a couple of nodes as one node.

Note that in VRML 1.0 it's required that a whole VRML file consists of exactly one root node, so we actually had to use some grouping node here. For example the following file is invalid according to VRML 1.0 specification:

#VRML V1.0 ascii

Sphere { }
Cube { width 1.5 height 1.5 depth 1.5 }

Nevertheless the above example is handled by many VRML engines, including our engine described in this document.

In VRML 2.0, you don't place children nodes directly inside the parent node. Instead you place children nodes inside fields of type SFNode (this contains zero (NULL) or one node) or MFNode (this contains any number (possibly zero) of nodes). For example, in VRML 2.0 Group node has an MFNode field children, so the example file in VRML 2.0 equivalent to previous example looks like this:

#VRML V2.0 utf8

Group {
  children [
    Shape { geometry Sphere { } }
    Shape { geometry Box { size 1.5 1.5 1.5 } }
  ]
}

Syntax of MFNode is just like for other multiple-valued fields: a sequence of values, inside brackets ([ and ]).

Example above also shows a couple of other differences between VRML 1.0 and 2.0:

While we're talking about VRML versions differences, note also that in VRML 2.0 a file can have any number of root nodes. So actually we didn't have to use Group node in our example, and the following would be correct VRML 2.0 file too:

#VRML V2.0 utf8

Shape { geometry Sphere { } }
Shape { geometry Box { size 1.5 1.5 1.5 } }

To be honest, we have to point one more VRML difference: as was mentioned before, in VRML 2.0 shapes are unlit by default. So our VRML 2.0 examples above look like this:

Figure 1.6. An unlit box and a sphere in VRML 2.0

To make them lit, we must assign a material for them. In VRML 2.0 you do this by placing a Material node inside material field of Appearance node. Then you place Appearance node inside appearance field of appropriate Shape node. Result looks like this:

#VRML V2.0 utf8

Group {
  children [
    Shape {
      appearance Appearance { material Material { } }
      geometry Sphere { }
    }
    Shape {
      appearance Appearance { material Material { } }
      geometry Box { size 1.5 1.5 1.5 }
    }
  ]
}

We didn't specify any Material node's fields, so the default properties will be used. Default VRML 2.0 material properties are the same as for VRML 1.0: light gray diffuse color and a slight ambient color.

As you can see, VRML 2.0 description gets significantly more verbose than VRML 1.0, but it has many advantages:

Let's take a look at another grouping node: VRML 2.0 Transform node. This node specifies a transformation (a mix of a translation, a rotation and a scale) for all it's children nodes. The default field values are such that no transformation actually takes place, because by default we translate by (0, 0, 0) vector, rotate by zero angle and scale by 1.0 factor. This means that the Transform node with all fields left as default is actually equivalent to a Group node.

Example of a simple translation:

#VRML V2.0 utf8

Shape {
  appearance Appearance { material Material { } }
  geometry Box { }
}

Transform {
  translation 5 0 0
  children Shape {
    appearance Appearance { material Material { } }
    geometry Sphere { }
  }
}

Figure 1.7. A box and a translated sphere

Note that a child of a Transform node may be another Transform node. All transformations are accumulated. For example these two files are equivalent:

#VRML V2.0 utf8

Shape {
  appearance Appearance { material Material { } }
  geometry Box { }
}

Transform {
  translation 5 0 0
  children [
    Shape {
      appearance Appearance { material Material { } }
      geometry Sphere { }
    }

    Transform {
      translation 5 0 0
      scale 1 3 1
      children Shape {
        appearance Appearance { material Material { } }
        geometry Sphere { }
      }
    }
  ]
}

#VRML V2.0 utf8

Shape {
  appearance Appearance { material Material { } }
  geometry Box { }
}

Transform {
  translation 5 0 0
  children Shape {
    appearance Appearance { material Material { } }
    geometry Sphere { }
  }
}

Transform {
  translation 10 0 0
  scale 1 3 1
  children Shape {
    appearance Appearance { material Material { } }
    geometry Sphere { }
  }
}

Figure 1.8. A box, a translated sphere, and a translated and scaled sphere