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From: fsfacca@avelon.lerc.nasa.gov (Tony Facca)
Newsgroups: comp.graphics,comp.lang.postscript
Subject: Re: Transpose Question
Keywords: rotate Page translate 0 -617
Message-ID: <1990Feb14.174304.26351@eagle.lerc.nasa.gov>
Date: 14 Feb 90 17:43:04 GMT
References: <1990Jan30.213715.25270@Neon.Stanford.EDU> <1990Jan31.010050.16064@deimos.cis.ksu.edu> <10519@microsoft.UUCP>
Reply-To: fsfacca@avelon.UUCP (Tony Facca)
Organization: NASA/Lewis Research Center, Cleveland
Lines: 28

In article <10519@microsoft.UUCP> t-dougls@microsoft.UUCP (Douglas Strauss) writes:
>I have just started to muck around with some postscript and wondering
>how the values of the transpose function are intpreted.  On the apple
>laserwriter I am using:
>90 rotate
>0 -617 translate
>Or pretty close to this right our the the RGB books.  What do these values
>for the translate refer to?  I would assume that it is the largest print area
>on the laser writer or something like that.
>
>Could somebody clarify this for me please.  I shall then stick to mostly
>reading and learn.  Thanks.
>

The translate command is used to transform what Adobe defines as the Current
Transformation Matrix.  The command, "Tx Ty translate" with no specified
matrix, will do a matrix multiplication T x CTM (where T is a 3x3 matrix as
described in the Red book) and push a new CTM onto the operand stack.

The reason for a 0 -617 translation is most likely to reposition the origin 
after a 90 degree rotation.  You should look at the Red book (section 4.4)
if you still don't get it.
--
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Tony Facca                     |     phone: 216-433-8318
NASA Lewis Research Center     |    
Cleveland, Ohio  44135         |     email: fsfacca@lerc08.lerc.nasa.gov 
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