Xref: utzoo comp.graphics:18891 comp.lang.postscript:9157
Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!mcsun!news.funet.fi!fuug!sti.fi!ttl
From: ttl@sti.fi (Timo Lehtinen)
Newsgroups: comp.graphics,comp.lang.postscript
Subject: Re: How do I draw a depth-cued line in PostScript?
Message-ID: <1991Jun28.001226.27919@sti.fi>
Date: 28 Jun 91 00:12:26 GMT
References: <1991Jun27.164001.2435@engage.pko.dec.com>
Reply-To: ttl@sti.fi (Timo Lehtinen)
Organization: Stream Technologies Inc.
Lines: 32

In article <1991Jun27.164001.2435@engage.pko.dec.com> davis@3d.enet.dec.com (Peter Davis) writes:
>
>In article <1991Jun26.140611.1052@canon.co.uk>, ads@canon.co.uk (Adam Billyard) writes...
>>The PostScript imaging model has no notion of variable shading over the
>>area to be filled. The metaphor is of opaque paint being pushed through
>>a stencil. Display PostScript extends this a little by including
>>transparency, ...
>
>Really? How? I've been working with Display PostScript for a while, and I have
>come across nothing that either explicitly or implicitly allows transparency.
>The only way to achieve transparent effects that I know of it to fill with a
>stipple pattern using imagemask, but this is possible in regular as well as
>Display PostScript.
>
>Can you explain?  This would be very VERY useful.


The version of Display PostScript in the NeXTstep GUI supplied by 
NeXT, Inc. has transparency. I.e. an explicit alpha channel and a 
set of PIXAR-style operators to doo compositing etc.

Perhaps this is what the original author was referring to. NeXTstep
ofcourse is not available on any other platform other than NeXT.
(IBM has a license, but doesn't seem to be doing anything with it.)

Timo

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