Newsgroups: comp.graphics
Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!batcomputer!cornell!uw-beaver!ubc-cs!news.UVic.CA!csr!bcorrie
From: bcorrie@csr (Brian  Corrie)
Subject: Re: Scene Description Standard
Message-ID: <bcorrie.674238180@csr>
Keywords: RenderMan, RIB, modeling languages, animation languages
Sender: news@sol.UVic.CA
Nntp-Posting-Host: csr.uvic.ca
Organization: University of Victoria
References: <1991Apr30.003612.16050@mks.com> <1991May14.015051.10455@pixar.com>
Date: 14 May 91 16:23:00 GMT

aaa@pixar.com (Tony Apodaca) writes:
>	There has been a lot of traffic about what RenderMan is and is not
>in the past couple weeks, so I hope I can clear up some of the confusion.
>My credentials: currently Chief Architect of the RenderMan Interface, and
>one of the Unknown Implementors of both of Pixar's image synthesis products.
>	First, I must apologize for the untimeliness of this post.  As I
>type this, it is May 12, and only today has our news feed deigned to send us
>your postings from April 30!  A friend at UCSC has sent me some postings
>up through May 9 (thanks Rob!), but I have not seen the whole thread.

I was wondering why no one from Pixar was speaking up. Now we know. Today,
I got three postings from Pixar defending RenderMan 8-) Nice to hear from you
guys...

[Stuff deleted about ordering the RenderMan spec. etc]

>	I want to correct some factually incorrect statements that have
>been made about RenderMan.  Someone mentioned...
>> Renderman is grossly inefficient for polygons, as it takes a
>> [vertex, vertex, close] instead of a list of vertices and a face list.
>Check out RiPointsPolygons().  I think this will do what you want.

This misunderstanding was caused for a couple of reasons I think.

1) John Woolverton (as he explains in his recent posting) based his info
on the output of modelers that he used, none of which used this feature.

2) RIB is purely a textual format, correct? That is there are no variables
or static arrays that can be declared. Therfore, if you have a large number
of polygons to be declared with a large set of common vertices, then you
either declare separate polygons with duplicate vertex info, or use one
large RiPointsPolygons declaration for all polygons. For exmaple, to be
really efficient (as in the OFF file format) you would declare a list of
all vertices in an object, and then the entire list of polygons that makes
up the entire object. This isn't terribly obvious that its the way to go,
especially when you are thinking of the C binding and then convert that to
RIB. This makes for a single RiPointsPolygon call that could have thousands
of polygons in it, not the most obvious way to go (but the most efficient)
when you think about it.

>	Someone claimed that Pixar did not use RenderMan and RIB for its own
>animations.  We most certainly do, and we are quite proud of it.
>We sell what we use, we use what we sell.

I hope this wasn't my statement that gave you this impression. If so, what I
meant to say was that I thought Pixar uses other tools/langauges as well/on top
of RenderMan. You confirm this later in your article when you say...

>	So, what have we learned?  Modeling languages are hard.  Very hard.
>This is not to say impossible, and I look forward to the day when a smart
>person solves this problem.  But Pixar didn't (and doesn't) know the answer.
>Pixar has at least 3 modeling and animation languages we use, each of which
>handles some things very well and other things very poorly.

[More explanation/description deleted]

>	Being "Chief Architect", I am privy to a lot of private plans of
>various companies using RenderMan, and it would be indiscreet for me to let
>on what I know, even by innuendo.  Let me just say, there is more in store
>than just bug-fixes for Reyes....

Sounds interesting, I'll keep my eyes and ears open 8-)

[Interesting exlpanation of the design decisions wrt RenderMan deleted]


>-- 
>UUCP:		{sun,ucbvax}!pixar!aaa		Tony Apodaca
>Internet:	aaa@pixar.com			Pixar, Richmond, CA, USA
>    "And in the end, the love you take is equal to the love you make."

Later,
	B

--
                  Brian Corrie (bcorrie@csr.uvic.ca)
Under the most rigorously controlled conditions of pressure, temperature,
volume, humidity and other variables, the organism will do as it damn well
pleases. Sounds like some of the code I have written......  8-)
