On Sun, Apr 25, 2021 at 4:03 PM Sergio Callegari <[email protected]> wrote:
> On Fri, 23 Apr 2021 09:57:13 +0200 luigi.scarso at gmail.com (luigi > scarso) wrote: > > > On Fri, Apr 23, 2021 at 9:48 AM Sergio Callegari <sergio.callegari at > > unibo.it> > > wrote: > > > > > Hi, > > > > > > I have noticed that luatex now supports variable fonts and I've started > > > experimenting. I am asking a question here but I am unsure if it is > > > actually tied to luatex or luaotfload or maybe fontspec. In case, > please > > > be so kind to address me to the correct forum. > > > > > > > > hm, luatex and luahbtex don't support variable fonts directly, > > it's a matter of the format (latex, context, optex... ) . > Thanks for providing this info. Can you be so kind to expand a little, > as there are still a couple of things that are not 100% clear to me? > > - Common widom found on the net is that variable fonts work only with > the LuaTeX engine, no others and that this become possible only with > LuaTex 1.13. As a matter of fact, xeTeX works without an hiccup on the > file, but after it it is impossible to make a PDF because dvipdfmx > reports "invalid font" . This suggests that the engine and specific the > part of it responsible for the PDF generation plays a role. The only > item that comes to my mind given the situation is lua. If so, would it > be luaotfload the upstream to ask the question to? > > yes > - The errors reported when attempting to use variable fonts appear to > happen /after/ the format and the tex machinery has completed its work, > that is after the: > > 406 words of node memory still in use: > 3 hlist, 1 vlist, 1 rule, 2 glue, 3 kern, 1 glyph, 4 attribute, 48 > glue_spec > , 4 attribute_list, 1 write nodes > avail lists: 2:17,3:4,4:1,5:28,6:2,7:116,9:14 > > What appears to fail is the step following this one, that is the PDF > generation. This looks consistent with what happens in xetex. But if I > am correct, in both pdftex and luatex the pdf generation is unseparable > from the engine, apart from the role of luaotfload... > > Any suggestion? > > LuaTeX has a pdf and dvi backend (as pdfTeX) and a native management of "traditional" postscript / truetype /opentype fonts -- but not the font variations. "Variable fonts" are managed by the format which, basically create an instance of a "traditional" font from the values of the axes --- this is possible because LuaTeX has the concept of "virtual" font, see https://www.tug.org/svn/texlive/trunk/Master/texmf-dist/doc/luatex/base/luatex.pdf?view=log The first implementation (in ConTeXt) was in 2017: http://www.gust.org.pl/bachotex/2017-pl/presentations/hhagen-2-2017.pdf https://www.tug.org/TUGboat/tb38-2/tb119hagen-variable.pdf -- luigi
