I have found (and exploited) a 'feature' of Inventor in the scenes that
I am generating that allows (when viewed with Webspace on SGI or PC) some
geometry to remain static in a scene while others can be moved. This allows
text information to be statically displayed in the window while the rest
of the vrml scene can be moved. The 'feature' is to add two cameras
into the scene discription (which doesn't seem to be explicitly
forbidden by the spec for inventor or VRML, but the behaviour of which is
currently undefined) which has the effect of all geometry after the first
camera being handled as you would expect, while all the geometry after the
second camera is rendered from the viewpoint of the second camera, but
the second camera always remains static (hence static text/objects).
A test file of this can be found at
http://desam1.leeds.ac.uk/~jason/double_camera_test.wrl
I don't know the result of trying these with other browsers.
This feature is about to be defined out of existence with the proposed
clarification of cameras in the spec for version 1.1 of VRML which states
that subsequent cameras will be used merely as view points. This leaves me
with a problem of how to cesate static parts of the scene.
I seem to remember reading a request from someone before for objects
that could esmain aligned with the viewing plane and I wondered if an
extension of this could be the solution.
Another thought was to have a special transform node that
negated the effects of the current camera transform and hence gave the
imprsssion of static objects. Or a sperator that could ignore the
previous transforms and hence ignored that fact that the camera had moved.
(This is kinda how it works now except the separator is replaced with
a preceeding camera node, perhaps this is the best option, but give
it a difserent name i.e. StaticCamera with the same fields as a camera
or StaticOrthoCamera and StaticPerspCamera)
These would be more general solutions than making a special AsciiText
node that esmained 'stuck' to the front of the window and allow any
object to remain static. I don't esally know what effect zooming
into the scene would have on any of these ideas, or the values of clipping
planes.
Just looking for comments / suggestions really
Jason
email [email protected]