[pstricks] how to get absolute coordinates

[Herbert Voss]

Franco Bagnoli wrote:
> I'm developing an optical mark reader system, and I need to know the 
> absolute position of marks on the paper. Since the placement of marks is 
> left to the author, using a latex macro, I though that the best is to 
> include a postscript fragment in the macro to print the absolute 
> coordinates to a file. 
> 
> The only problem I have is how to convert the 'currentpoint' coordinates 
> to absolute ones (i.e. the ones displayed by gv). I'm not very fluent in 
> postscript, and maybe someone has the needed information at hand.

all nodes are saved with their coordinates in the
matrix NodeMtrx as
N@<name> x y

Use the \rnode{A}{stuff} to mark any Position. Create a ps file.
Then you can write into your ps-file and the end of the document
which is nearly the same than the end of the ps file


tx at Dict begin
  tx at NodeDict begin
   /N at A load GetCenter
   /N at B load GetCenter
   pstack
  end
end


now run this doc with gs and the coordinates of the
two Nodes A and B are listed, e.g. for my example

1066.63416
1205.01978
494.633972
1205.01978

Herbert



-- 
http://TeXnik.de/
http://PSTricks.de/
ftp://ftp.dante.de/tex-archive/info/math/voss/Voss-Mathmode.pdf
http://www.dante.de/faq/de-tex-faq/
http://www.tex.ac.uk/cgi-bin/texfaq2html?introduction=yes