Re : SPEC - 3d menus

steve ([email protected])
Thu, 27 Apr 1995 09:59:16 GMT0BST

> Actually it would be neat to be able to make any object (or subtree)
> always face the user, opposed to just text. The problem is that a
> transformation that changes with the viewpoint is not something we can
> currently encode into the scene. Perhaps a different solution to the
> same problem would be to add an fixed_orientation field to the
> coordinate3 node, that would render any nodes that inherit from it such
> that their orientation remains fixed as the viewpoint changes. This
> would work for both 3D text and would be really handy for things ike
> floating 3D menus that you want to face the users so their always
> pickable.

The best way to implement 3D menus (or more generally objects that
must always face the user, and keep up wit the user as they navigate
around in space), is to 'attach' the menu objects to the head.

If both the orthographicCamera and perspectiveCamera nodes allow
child nodes (seperator, WWWAnchor etc.) then such objects can be 'attached'
to the user's head - the objects are transformed as normal, but
always inherit the position/orientation of the viewpoint.

The main problem is that in this case, these menu objects are always
in view - this can introduce some visibility problems, when you
cannot see the actual world for the menus in front of you! Enabling
and disabling visibility could be done using the switch statement -
switching to a NULL child effectively disables the other child
(the individual browsers would have to implement the control of this
switch statement as there are no interactions defined yet) an
interactive 'toolbox' can be implemented.

>>-------------------------------------<<
Steve Ghee ( [email protected] )
Director of Technology

Division Ltd
19 Apex Court
Woodlands
Almondsbury
Bristol, UK
BS12 4JT
Tel : +44 1454 615554
Fax : +44 1454 615532
>>-------------------------------------<<