On 2020-03-05 at 10:30:24 +0100, Hans Hagen wrote:
On 3/4/2020 9:02 PM, Matthias Nagel wrote:
However, XeTeX also uses OpenType and the odd kerning does not appear in XeTeX. Does this imply that Libertinus and XeTeX both handle spacing though not in accordance with the specs, but handle spacing at least consistently with each other? Of course, that would be a very unlucky situation. In that case fixing the font in accordance with the OpenType specs and LuaTeX would break the font for XeTeX.
I never looked into how xetex does it but I think that when its math was implemented there were hardly any opentype math fonts around. So, It might have settled on some mixed "old school tex rendering" and "at that time assumes opentype rendering" which then mostly meant "cambria with its math parameter system".
Hans, AFAIR you held a talk at TUG 2008 in Cork about a script you wrote which creates OTF font samples. In one example of your presentation glyphs supposed to appear only at the end a word erroneously appeared in the middle of the word. At the coffee break I asked Jonathan Kew how this can happen. He told me that there were at least three font vendors who interpreted the OTF specs differently. Mathias said
fixing the font in accordance with the OpenType specs [...]
Sure, but what exactly should be done if the specs are ambiguous? So far only ordinary text fonts were considered. Even if XeTeX and LuaTeX interpret the specs differently, the advantage of LuaTeX is that things can be fixed if necessary. The main problem seems to be that the OTF specs are ambiguous. Maybe packages like microtype can try to make these differences invisible to end users, more or less. Math fonts are more problematic because they are more complex and the number of potential developers is quite small. Regards, Reinhard -- ------------------------------------------------------------------ Reinhard Kotucha Phone: +49-511-3373112 Marschnerstr. 25 D-30167 Hannover mailto:reinhard.kotucha@web.de ------------------------------------------------------------------