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From: ttl@astroatc.UUCP (Tony Laundrie)
Newsgroups: comp.graphics,comp.lang.postscript
Subject: Re: Transpose Question
Keywords: rotate Page translate 0 -617
Message-ID: <3100@astroatc.UUCP>
Date: 18 Feb 90 18:48:58 GMT
References: <1990Jan30.213715.25270@Neon.Stanford.EDU> <1990Jan31.010050.16064@deimos.cis.ksu.edu> <10519@microsoft.UUCP> <1990Feb14.174304.26351@eagle.lerc.nasa.gov>
Reply-To: ttl@astroatc.UUCP (Tony Laundrie)
Organization: Astronautics Technology Cntr, Madison, WI
Lines: 24

In article <1990Feb14.174304.26351@eagle.lerc.nasa.gov> fsfacca@avelon.UUCP (Tony Facca) writes:
>In article <10519@microsoft.UUCP> t-dougls@microsoft.UUCP (Douglas Strauss) writes:
>>I have just started to muck around with some postscript...
>>90 rotate
>>0 -617 translate
>>...What do these values for the translate refer to?
>
>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.
>

Let's not scare the guy away with mathematics!  When the PostScript printer
is in it initial state, the origin is in the lower left corner of an
8.5 x 11 inch page.  90 rotate means "hold your finger on the origin and
spin the piece of paper clockwise 90 degrees."  The effect will make
the origin be in the upper left corner of an 11 x 8.5 inch page.

0 -612 translate means "move the origin (for all future coordinate
references) to coordinate (0,-612).  Since the initial units for PostScript
are points, of which there are 72 per inch, the effect of "0 -617 translate"
is to move the origin down 8.0 inches, placing it in the lower left corner
of that 11 x 8.5 inch page.