Anchor Node

If you're not familiar to grouping nodes in VRML see the section Creating Hierarchical Node Structures for general information on grouping. 

The Anchor node lets you define a set of objects as an link to a url. When you click in one of the objects within an Anchor node the url will be fetched. 

Anchor nodes can also be used to set a given Viewpoint. Examples will be provided bellow. 

When the user has the mouse over an object contained in an Anchor node the url will be displayed.

 The following fields are present: 
  • children which contains all the nodes included in the group. 
  • url specifies the url to be fetched or a Viewpoint to become active. You can specify multiple locations if you want to, the browser will look for data in those locations in decreasing order of preference. 
  • parameter supplies additional information for the browser. For instance you can specify the target window where the url should be displayed. 
  • description specifies a string which will replace the url information given to the user when the mouse is over an object contained within an Anchor. 
  • bboxCenter specifies the center of a box that encloses the nodes in the group. The value for this field is a 3D point. 
  • bboxSize specifies where the size of a box that encloses the nodes in the group. By default this field has a value of -1 -1 -1, which implies that no box is defined. The values for this field must be greater than or equal to zero. If the children nodes do not fit inside the box defined the results are undefined. 
  • The latter two fields are optional. They can be used by the browser for optimization purposes. 

    Syntax: 
    Anchor { 
    children [ ] 
    url [ ] 
    parameter [ ] 
    description "" 
    bboxCenter 0 0 0 
    bboxSize -1 -1 -1 

    Examples: 
    Anchor {
     
    children [ Shape geometry Sphere { } ] 
    url "http://www.my_server.pt/my_world.wrl" 
    description "My World" 
    parameter ["target=my_frame" ] 
    In the above example when the mouse is over an object contained in the Anchor node a prompt will be displayed with the message "My World" (If description was absent the prompt would display the url specified). When the user clicks an object contained in the Anchor node the specified url is fetched and displayed in the frame named "my_frame". 

    The next example shows an Anchor which is linked to a Viewpoint. When the mouse is over an object contained in the Anchor node a prompt will be displayed with the message "My Point of View". When the user clicks an object contained in the Anchor node the specified Viewpoint becomes active. 
    Anchor {
     
    children [ Shape geometry Sphere { } ] 
    url #my_viewpoint 
    description "My Point of View"