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GNU Unifont is a fontface licensed under the GNU GPLv2 or later with this exception:

The license for the compiled fonts is covered by the above GPL terms with the GNU font embedding exception, as follows:

As a special exception, if you create a document which uses this font, and embed this font or unaltered portions of this font into the document, this font does not by itself cause the resulting document to be covered by the GNU General Public License. This exception does not however invalidate any other reasons why the document might be covered by the GNU General Public License. If you modify this font, you may extend this exception to your version of the font, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.

When I use this fontface in a game, does the game fulfill the definition of being a "document" or do I need to license the game under the GPL?

Details about how the font is used:

  • The game engine would use the font-face to render text on GUI elements.
  • I might create 2d images which include characters from that font-face and use these as textures in the game.
  • This one might hinge on the definition of "incorporate" Great question – Martijn Nov 2 '15 at 22:18
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Typefaces are generally not eligible for copyright. They aren't in the US at all, as established in Eltra Corporation v. Barbara A. Ringer, and in many other places (UK, Ireland, Switzerland and others), the use of a font does not infringe on the copyright of a font.

A font file is a file that contains points along which curves are drawn to generate a character. In the US, these files have been found to be eligible for copyright protection as software in Adobe Systems, Inc. v. Southern Software, Inc. So while the printed character has no copyright, the font file used to generate it does.

If your game uses the font file to generate textures, the original expression of the font file is lost, and is not covered under copyright at all anymore in the US. This leads me to believe that in the US, the exception does exactly nothing that you weren't permitted to do already, at least for this scenario.

When you distribute the font file alongside the game as a separate or semi-separate install (you have to make clear the font is a separate product when the user installs it, but it may be part of the same installer), this doesn't count as making a combined work according to the license FAQ.

In the scenario where you extract the representation from the font file, and use it in your software, then the game and the font together would most likely become a work that has to be distributed under the GPLv2+.

I don't know how game engines work exactly, and how they interact with fonts. If you can install the font separately for the in-game text, you can follow the semi-separate install route. If the font somehow gets absorbed in the game engine, then you will have to distribute under the GPLv2+.

Typefaces can be protected with design patents as well. Because the license is GPLv2+, you can use it under the GPLv3, which removes this concern with its anti-patent clause.

  • Can you provide some evidence that typefaces are uncopyrightable? That goes against everything I've ever seen, and surely needs to be referenced on this site. – curiousdannii Nov 3 '15 at 0:20
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    @curiousdannii included relevant case law. – Martijn Nov 3 '15 at 9:03
  • @Martijn +1 for a well documented answer – Philippe Ombredanne Nov 4 '15 at 15:03
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Incorporating GNU Unifont in a software means that software has to be GPL.

Unifont uses the same GPL exception GNU FreeFont uses. The GNU FreeFont website has a FAQ which explains this case:

Can I incorporate GNU FreeFont into my (proprietary/non-GPL) software?

Only for your own personal use, or use within your organization only. If you distribute software that incorporates elements of GNU FreeFont, the distribution as a whole must be released under the GPL.

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    I do not know why this answer has been downvoted. The answer is not wrong per se, but the quote and interpretation provided by the FAQ sound utterly wrong and an incorrect understanding of the GPL. – Philippe Ombredanne Nov 2 '15 at 15:22
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    @PhilippeOmbredanne FreeFont is part of the GNU project. Do you want to imply that the GNU project do not understand their own license? There is no more authoritative source regarding GPL interpretations than the GNU project itself. – Philipp Nov 2 '15 at 17:29
  • what I am saying is that 1. "incorporate" is a vague term, 2. there are several case where you might "incorporate" a font in proprietary software without having your whole code subject to the GPL. So in that sense yes, I am saying that this commentary provided on this FAQ are not making assertions subject to interpretation and not really helping and not correct in every cases. – Philippe Ombredanne Nov 3 '15 at 13:24
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My take is that a document could be understood here as anything that used the font for rendering. To be sure that is a correct interpretation ask the authors of this font.

There is some discussion here, by the author of this license exception:

Quoting the GNU Freefont FAQ:

Can I use GNU FreeFont without restriction in my printed documents (reports, brochures, books, logos, etc.)

Yes.

The license restricts only the distribution of the font itself, or derivatives thereof — documents printed with the font are regarded as output of the font, not the font itself.

  • @unor : between my post and your edit, the content of gnu.org/software/freefont/FAQ.html has changed ... really weird – Philippe Ombredanne Nov 2 '15 at 15:23
  • As far as I see, my edit didn’t change the content of the FAQ answer you quoted, only the formatting. The "inline" revision comparison is confusing, but the "side-by-side" views show correctly that nothing from the content changed. – unor Nov 2 '15 at 15:47
  • @unar: my bad, indeed the diffs display are borked. – Philippe Ombredanne Nov 2 '15 at 15:57
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    That strikes me as a fairly disingenuous piece of quoting from a FAQ. That same FAQ explicitly addresses the question of distributing the font as part of a piece of software - the very question asked by the OP - yet you've chosen to quote a different part, which addresses a different issue, and claim that it's really not different. – MadHatter supports Monica Nov 3 '15 at 6:18
  • @MadHatter the question is as much about rendering as it is about embedding. The way the font will be used by the rendering engine is not defined. – Philippe Ombredanne Nov 3 '15 at 13:28

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