Re: Announcement: GDHE 3.2

You wrote (in your message from Friday 27)
 > On Fri, 27 Jun 2003, Matthieu Herrb wrote:
 > 
 > [...]
 > >  > Do you plan to add some "symbolic representation" of all 3D objects?
 > >  > (As the scene graph in Coin3D or so.)
 > > 
 > > It will be needed in order to be able to implement a 3D user
 > > interaction. But I'd like to be able to hide this representation for
 > > users that don't need it. 
 > 
 > Agreed. Do you have any links about where this kind of "scene graph"
 > stuff is already designed/implemented in a viewer-independent way?

No. I've not done any serious investigation in this direction. I've a
couple of ideas but I currently lack time to try to implement them. 
If someone has references I'd be interested to have at least a look at
them. 

 > [...]
 > > The frame I mentionned here is a visual representation (ie 3 arrows of
 > > a given length drawed at a given position + orientation. You use the
 > > OpenGL transforms to place it at a relative position with respect to a
 > > given object. 
 > Ok, but it doesn't "snap" to the closes geometric primitive, does it?
 > (Which is a handy feature to have in a GUI, because mostly one wants
 > to attach frames to such geometric features...)

It is all manual. You have to enter numerical coordinates in the
scripts. For now there are no helpers of any kind, except for what you
see when the script is interpreted by the redraw code.
But it doesn't mean it can't be done. 

For example, in the case of an all-terrain vehicule on an uneven
terrain you can imagine to plug in a 3D placement function that will
compute the exact configuration (and z position) of the vehicule so
that all the wheels are in stable contact with the ground.
This will allow you to only specify X, Y and theta coordinates to the
display system and let it find the other parameters. 

 > 
 > [...]
 > > A visualisation system only generates images. The fact that GDHE
 > > computes some interesting data to generate those images, or that it
 > > can also accept user input is marginal imho. 
 > 
 > Can I interpret this statement as your saying that you have no
 > interest in seeing GDHE evolve into a full-fledged two-way GUI? :-)

At the beginning of the project I had no interest in that aspect. Now
I feel that there are applications for which it could be useful so I
have an interest into implementing it (or in seeing someone else doing
it in a way that looks compatible with how I'd like it to be done). 

-- 
					Matthieu