Re: Justification

Johannes N. Johannsen (jojo@well.com)
Wed, 09 Apr 1997 16:33:51 +1200

Curtis Beeson wrote:
>
> My point is that if VRML is to succeed, it must cater to the content creator
> and not necessarily computer science academic like me. Therefore, when we
> discuss an "object-oriented" methodology, I think it essential to consider an
> "object-oriented" approach to VRML content creation and not limit our thinking
> to the VRML file syntax.
>
> The file format will certainly play a role in how the content creator creates
> their worlds, but a typical VRML file consists mostly of vertices, coordinates,
> and other data types the you really don't program by hand. Thus, I think that
> most VRML content producers will use modelers and other authoring tools to
> produce their content. It is therefore in this context that we should find an
> object-oriented solution.
>
It's my understanding that that is the context we are already working in
when discussing the file format. So I'm not sure what you are saying...

But then again, maybe I'm not making sense... the authoring tools are
going to be targetted at specific problems. They will read in VRML,
create their objects, change them with their UI, and write out VRML.

In terms of how this work, the wrl file is first read into an object
structure that follows the language specification in a straightforward
way. This object structure is then transformed into a problem domain
specific structure. Its this transformation that is affected by the
file format, so that's why I think we are already discussing this in the
context of authoring tools.

For example, if your authoring tool is attaching a texture to an
Appearance node, it must limit the texture to ImageTexture,
PixelTexture, MovieTexture. At the moment VRML defines these as
SFNodes, indistinguishable from the 50+ other nodes. So your authoring
tool has to restrict the texture attachment to these three. But if the
language (file format) defined these as subclasses of Texture, then when
the wrl file is parsed, that work would be done already. You're free to
move on to more advanced things in your authoring tool, like providing
cool content producing widgets for your GUI.

JJ