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From: kurt@cashew.asd.sgi.com (Kurt Akeley)
Newsgroups: comp.graphics,comp.unix.aix
Subject: Re: Vector fonts for IBM GL (AIX 3.1 on RS/6000)
Keywords: vector fonts, GL
Message-ID: <1990Nov7.172110.17939@odin.corp.sgi.com>
Date: 7 Nov 90 17:21:10 GMT
References: <1912@taurus.BITNET>
Sender: news@odin.corp.sgi.com (Net News)
Reply-To: kurt@cashew.asd.sgi.com (Kurt Akeley)
Organization: sgi
Lines: 33

In article <1912@taurus.BITNET>, blumzi@TAURUS.BITNET writes:

|> Hello GL users,
|> 
|> As far as I remember Silicon Graphics's GL included vector fonts.  Somehow
|> this feature seems to not apear in IBM's GL (which is supposed to be
|> compatible).  Is it realy so?  Can I somehow add this functionality?
|> 
|> As a long shot, is it possible to mix XDPS with GL ?!?
|> 
|> Any pointers are welcome ...

Vector fonts have not been included in SGI GL releases for a long time,
perhaps as long as 4D machines have been shipped.  The IBM version of the
GL is comparable to the 3.2 release of the SGI GL, which certainly didn't
include vector fonts.

It is easy to draw vector fonts using the GL, however.  Be forewarned,
though, that using the relative move and draw commands, which is a
traditional and seemingly good technique, is not a good idea.  Rather,
each vector character should be drawn using its own matrix, from a
representation using absolute coordinates.  The required matrix push,
translate, scale, and pop do not add up to significant overhead on
modern GL systems, and besides, if your character scale was not equal
to the scale of the image being overdrawn, all but the translate were
required anyway.

Many recently-added GL features, such as local lighting computations,
do not work well with relative drawing commands.  Both these drawing
commands and the related concept of current graphics position are
obsolete, and will eventually be removed from the GL.

-- kurt