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From: ewhac@well.UUCP (Leo 'Bols Ewhac' Schwab)
Newsgroups: comp.sys.amiga
Subject: Re: IFF for 3D packages?
Message-ID: <4592@well.UUCP>
Date: Tue, 1-Dec-87 03:21:22 EST
Article-I.D.: well.4592
Posted: Tue Dec  1 03:21:22 1987
Date-Received: Fri, 4-Dec-87 21:24:09 EST
References: <4VfpM8y00WAKzW005j@andrew.cmu.edu>
Reply-To: ewhac@well.UUCP (Leo 'Bols Ewhac' Schwab)
Organization: Hole Earth 'Lectronic Loss (or words to that effect)
Lines: 45

In article <4VfpM8y00WAKzW005j@andrew.cmu.edu> mp1u+@andrew.cmu.edu (Michael Portuesi) writes:
>With all the talk about interchange programs between Videoscape 3D,
>Sculpt 3D, Forms in Flight, etc etc. I begin to wonder why an IFF
>format for describing three-dimensional objects has not surfaced.
>After all, isn't the whole intention of IFF to avoid kldugy
>conversion programs and allow various packages to work in tandem?
>
	Yup.  However, a general specification for a 3D object is inherently
more complicated than a spec for a bitmap image.

	The idea behind IFF is for it to be as general as possible.  3D
objects can contain any number of characteristics, all of which have to be
accounted for in the standard.

	A 3D object is (usually) defined using points and polygons.  How are
the coordinate triplets stored?  IEEE floating point?  Some systems have no
concept of IEEE.  What about each polygon?  How do you specify its
characteristics?  Is it matte?  Shiny?  Mirror-surface?  Transparent?
Translucent-diffusive?  Luminous?  Is this object merely a collection of
flat polygons, or is it truly solid (it makes a difference if you're ray-
tracing something made out of glass)?

	What about the points?  Do they specify a polygon, or a bicubic
surface?  Or perhaps they specify something else.  How about lighting?  Are
you using a point source, or directional source?  Do lights have color?

	Finally, how do you format all this information in such a way that
it can be read and written easily by more than one system?  Remember that
some CPU's have different ideas about hi-low byte ordering for words/
longwords, etc.

>It wouldn't be hard at all to adopt such a standard.  Everybody need
>only offer IFF capability with the next release of their package,
>with backwards compatability for the old format.
>
	Adopting a standard is easy.  Creating one is the tricky part.....

Addendum:  I'm led to understand that, in fact, a 3D object IFF standard is
being hashed out on BIX by Volk & Co.

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