Re: plain TeX: different \hsize and \vsize for odd and even pages (was: plain TeX: different margins for odd and even pages)

On Wed, 2026-04-08 at 17:42 +0000, Rodolfo Medina wrote:
> suppose I want to do the
> same with \vsize and \hsize, i.e. set a different \vsize (and/or
> \hsize) value
> from odd to even pages: is it possibile?=C2=A0 I mean in `pure' plain TeX=
.

Is this what you're looking for?

Note how we check \ifodd\pageno *after* \plainoutput because that is
where it gets incremented and we want to set it not for this page but
for the next one.

Cheers,
Tim

\newdimen\oddhsize \oddhsize=3D100truemm
\newdimen\oddvsize \oddvsize=3D150truemm
\newdimen\evenhsize \evenhsize=3D200truemm
\newdimen\evenvsize \evenvsize=3D250truemm
\vsize=3D\oddvsize \hsize=3D\oddhsize %since we start with an odd page
\output=3D{%
	\plainoutput
	\ifodd\pageno
		\global\vsize=3D\oddvsize
		\global\hsize=3D\oddhsize
	\else
		\global\vsize=3D\evenvsize
		\global\hsize=3D\evenhsize
	\fi
}
Page 1\vfil\hrule\eject
Page 2\vfil\hrule\eject
Page 3\vfil\hrule\eject
\end