It is in the default, Liberation Sans.

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On 2020-12-29 08:08, Michael Marx wrote:

As a general comment to this text() talk, I think the way the text()
'spacing' parameter is implemented must be wrong in OpenSCAD, using
anything but default value gives odd results, try for example

linear_extrude(1)
text("Hello World", spacing=2);

I noticed this since I added (partial) support for text() in .scad
scripts when executed from AngelCAD v1.5-06.

Btw., why is there a need for a "font cache" in OpenSCAD?

Carsten Arnholm

spacing= makes more sense with mono spaced fonts

linear_extrude(1)
text("Hello World", spacing=2, font="liberation mono");

There are issues with spacing and alignment, which I'll mention under Jordan's 'metrics' thread
later.

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On 12/29/2020 1:29 AM, arnholm@arnholm.org wrote:

It's a straight multiplier on the "advance" value for each glyph.

Yeah, that can go wrong in a couple of ways.  A series of Ws will get a
lot more space between them than a series of Is.

You might think that it should be a value that's added to the advance
value, but that forgets the fact that OpenSCAD (through HarfBuzz)
supports ligatures.  If you want even weirder spacing, check out
"Difficult" in Calibri:

What's going on there is that "ffi" is compressed down into being one
glyph, and then the extra spacing is applied.  And since the "ffi"
ligature is extra-wide, the extra spacing after it is extra-wide too.

I don't know what the right answer is, but I'm going to draw a line and
say that I'm not going to try to fix it as part of my text metrics project.

On 29.12.2020 23:08, MichaelAtOz wrote:

That is avoiding the issue i mentioned. Spacing should have a meaningful
definition with any font. A natural interpretation is for it to define
the size of the spacing between the characters.

In my opinion, and why I made a comment, it is precisely because it is
implemented incorrectly in OpenSCAD it can't be used for anything but
mono spaced fonts (you could question its use there as well).

Consider this, I would expect zero spacing between the characters:

linear_extrude(1)
text("Hello World", spacing=0, font="liberation mono");

See attached "openscad_spacing0.png", where all characters are drawn on
top of each other, I don't think that is correct.

Compare with the same .scad code executed in AngelCAD, where you get
zero spacing between characters. I don't claim this to be perfect
either, but it makes much more sense to me.

Crsten Arnholm.

On 30.12.2020 00:14, Jordan Brown wrote:

And I think that is wrong.

I would think so, yes.

Fist of all, I don't see the ligature effect you are describing, even in
the very latest nightly: OpenSCAD version 2020.12.27.nightly (git
52eb8ec), see attached. That is probably something unreleased you have
added?

The discussion of ligatures seems to be making things more difficult
(pun intended) than required for the purposes of including text in
3d-printing models. What you showed is surely something different from
current OpenSCAD, even the latest nightly, and it does not seem like an
improvement when it comes to spacings.

Compare with the exact same .scad code Executed in AngelCAD 1.5-06
(attached screenshot), it does not need to be any more difficult than
that. AngelCAD does not use HarfBuzz, btw.

Carsten Arnholm

On 12/29/2020 9:25 PM, Carsten Arnholm wrote:

That's not an unreasonable answer, but isn't current behavior and
(except for the default) isn't compatible with current behavior.  Or
with the ligature issue discussed below.  (And perhaps others, with
combining characters.)

Net, I'm not optimistic about fixing "spacing" in the general case.

No, it's stock OpenSCAD.  (Right now I'm demonstrating it with 2019.05
on Windows 10.)  But it depends on the font; it only applies to fonts
that have ligature support.  Liberation Sans does not seem to have
ligature support.  I've been testing it with Calibri.

It depends on how picky you are about your text.  Typographers consider
ligatures to be important.  Are they important in 3D design and 3D
printing?  If you're just trying to put "ON" and "OFF" labels on a box,
probably not.  If you're trying to print plates for a printing press, maybe.

One might also wonder whether kerning, another "advanced" typographic
feature that OpenSCAD supports, is "required".  (Compare the spacing
between "AAAVVV" and "AVAVAV" - the same letters, just in a different
order.)

What does it do with this program and its variants?  (Also attached, in
case something mangles the non-ASCII text.)

israel = "יִשְׂרָאֵל";
harfbuzz = "حرف‌باز";
f = "Arial";
spacing=1;
direction = "rtl";

text(israel, font=f, spacing=spacing, direction=direction);
translate([0,-20,0]) text(harfbuzz, font=f, spacing=spacing, direction=direction);

For extra special fun, note that for this Hebrew and Persian text
OpenSCAD defaults to right-to-left.

Note:  there's no telling how the RTL text here will be presented by any
particular program.  As I compose this, Thunderbird is presenting it
correctly, where in "Israel" the first character, the yod, which looks
sort of like an apostrophe, is on the right.  I can sort of read Hebrew,
so I know which character is which, but I can't read Persian so I can't
say a lot about the "harfbuzz".  I can't even really see how the
individual characters in that string are constructed into the glyphs
that result. But I can tell you that there's a glyph that looks sort of
like a semicolon; it's supposed to be on the left.  On the other hand,
OpenSCAD's editor kind of mangles it.