This is very simple, and the main goal of the project was to dip my toes in Odin. I needed something interesting enough to keep me going, but fairly simple as I'm still just exploring the language.
This repo contains a parser for the jhf format of Hershey fonts. The parser is used to convert this format to a simple binary format and to implement a simple tool to explore the Hershey fonts.
Hershey fonts came into my radar after reading Daniel Holden's blog post about debug text. It turns out Mikko Mononen uses them in his excellent Skribidi, and of course Paul Burke wrote about them a while back.
They seem like a really nice way to put some text onto the screen where you might only have something like GL_LINES available on the rendering side.
The font_files folder contains some of the jhf files as distributed by solsta. You can grab extra ones from over there, however, I've only tested the Latin fonts, your mileage might vary with the Greek / Cyrillic / Japanese. My goal here is debug text rendering, so ASCII characters will suffice!
As the name suggests, it converts jhf to either text form (similar to Mikko Mononen's simple simplex or Daniel Holden's consolines), or to a new and shiny Binary Hershey Font (bhf) format! The idea is that you can then #load these binary files into Odin, decode the binary format, and be off to the races.
The binary format is straightforward:
# INFO SECTION
glyph_count -> i32, 4 bytes
offsets -> [glyph_count] i32, 4 bytes each
# GLYPH SECTION
glyphs -> [glyph_count]
- advance -> i16, 2 bytes
- coords_count -> i16, 2 bytes
- coords -> [coords_count]
- x -> i8, 1 byte
- y -> i8, 1 byte
offsets tells you how far to go into the file from the file start, and then each glyph is simply advance plus the x, y coords. The coordinates are expressed in such a way that the point at the left edge and baseline of the glyph is (0, 0). This choice makes writing the function to lay out the glyphs to the screen trivial. min(i8) (-128) is used to indicate an end of a segment. Check out the draw_text in common/utils.odin for details.
The idea behind the text format is that you can paste the resulting file into your odin project and you will get simple struct:
jhf_glyph :: struct {
advance: i8,
coords_count: i16,
coords: [<max_coords_per_font>]i8
}
followed by an array that stores the actual info for each glyph.
Explorer is a simple program to view how glyphs in each .jhf file look.
There are two modes - the glyph exploration and font preview.
To switch between them you can press F1.
-
In glyph exploration you can use
→/kand←/jto move between glyphs. Additionally, you can presscto visualize the separate segments within a glyph with different colors. -
In font preview you can use
=to increase font size and-to decrease it.
After The Hershey Fonts by sol_HSA
USE RESTRICTION:
This distribution of the Hershey Fonts may be used by anyone for
any purpose, commercial or otherwise, providing that:
1. The following acknowledgments must be distributed with
the font data:
- The Hershey Fonts were originally created by Dr.
A. V. Hershey while working at the U. S.
National Bureau of Standards.
- The format of the Font data in this distribution
was originally created by
James Hurt
Cognition, Inc.
900 Technology Park Drive
Billerica, MA 01821
(mit-eddie!ci-dandelion!hurt)
2. The font data in this distribution may be converted into
any other format *EXCEPT* the format distributed by
the U.S. NTIS (which organization holds the rights
to the distribution and use of the font data in that
particular format). Not that anybody would really
*want* to use their format... each point is described
in eight bytes as "xxx yyy:", where xxx and yyy are
the coordinate values as ASCII numbers.
*PLEASE* be reassured: The legal implications of NTIS' attempt to control
a particular form of the Hershey Fonts *are* troubling. HOWEVER: We have
been endlessly and repeatedly assured by NTIS that they do not care what
we do with our version of the font data, they do not want to know about it,
they understand that we are distributing this information all over the world,
etc etc etc... but because it isn't in their *exact* distribution format, they
just don't care!!! So go ahead and use the data with a clear conscience! (If
you feel bad about it, take a smaller deduction for something on your taxes
next week...)
The Hershey Fonts:
- are a set of more than 2000 glyph (symbol) descriptions in vector
( <x,y> point-to-point ) format
- can be grouped as almost 20 'occidental' (English, Greek,
Cyrillic) fonts, 3 or more 'oriental' (Kanji, Hiragana,
and Katakana) fonts, and a few hundred miscellaneous
symbols (mathematical, musical, cartographic, etc etc)
- are suitable for typographic quality output on a vector device
(such as a plotter) when used at an appropriate scale.
- were digitized by Dr. A. V. Hershey while working for the U.S.
Government National Bureau of Standards (NBS).
- are in the public domain, with a few caveats:
- They are available from NTIS (National Technical Info.
Service) in a computer-readable form which is *not*
in the public domain. This format is described in
a hardcopy publication "Tables of Coordinates for
Hershey's Repertory of Occidental Type Fonts and
Graphic Symbols" available from NTIS for less than
$20 US (phone number +1 703 487 4763).
- NTIS does not care about and doesn't want to know about
what happens to Hershey Font data that is not
distributed in their exact format.
- This distribution is not in the NTIS format, and thus is
only subject to the simple restriction described
at the top of this file.
Hard Copy samples of the Hershey Fonts are best obtained by purchasing the
book described above from NTIS. It contains a sample of all of the Occidental
symbols (but none of the Oriental symbols).