Re: LANG: VRML Transforms (fwd)

Greg Scallan ([email protected])
Mon, 9 Oct 1995 23:19:01 -0400

On Oct 9, 2:40pm, Robert Geiger wrote:
> Subject: Re: LANG: VRML Transforms (fwd)
> Hi Colin
> >b) Given that the majority of will be non-technical-types/artists who don't
> >understand homogeneous transformations, I think it is more important to try
> >to make the thing fairly idiot-proof than to cater for the 1% of cases where
> >this isn't what you are trying to do.
> >- particularly given that if you understand what is going on, then you will
> >also understand how to work around it.
> >
> Ahhh you speak to me! I haven't actually made much of an effort to verify
> this is the problem with my world, but With webFX a series of spheres which
> I scale and translate appear within the walls of my cuboid maze, but with
> WorldView many of the spheres appear outside the cuboid maze. If this is my
> problem as I think, this problem is no longer within the esalm of a
> theoritical problem, there are very esal-world implications of the order in
> which transforms are apply and how various browser in use now impliment
> them! comments?

Coming from someone who has programming in 3D for several years, I still
find transformation tough to deal with from both a programming and mathematical
paradigm. There are several issues here:

1) The VRML spec needs to be clarifed on some of the details that have
been brought up here ... I'm sure they will be soon.
2) several simple .wrl files need to be created showing what happens as you
pre and post-concatenate transformations, specifically looking at the
the most confusing aspect being rotations and scales on objects about
arbitrary points (something perfect for the testbed! ... volunteers anyone?)
3) Keep in mind that alot of the viewers you are using are in BETA, and so
they have bugs. My suggestion would be to find a viewer that is not
in Beta but claiming to be 100% VRML V1.0 compliant, test your .wrl file
in that. If a BETA viewer shows it differently, send a copy of the .wrl
file to that companys support and they'll fix it, hopefully for the next
beta.

You can send any files you think do not work in WebFX to [email protected]
and we'll check it out.

Greg

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