2 This is a font of music symbols. All MF sources are original. Most of the
3 documentation is in comments in the MF code.
5 Non-square pixels are not supported; with other words, the horizontal and
6 vertical resolution of the output device must be the same.
8 Currently, outline fonts are created by using `autotrace', but we are
9 already in the process of converting the MF code directly to PostScript code
10 with a tool called `mf2pt1', which in turn calls `FontForge' to postprocess
11 the output (mainly to remove outline overlaps and to add hints).
13 The recommended calling sequence of mf2pt1 is
15 mf2pt1 --rounding=0.001 <other options> <font>
17 You need mf2pt1 version 2.1 or newer.
20 Here some guidelines to assure a clean conversion.
22 . Never use `---'. Replace it with `--' together with explicit path
23 directions (if necessary).
25 . Don't use self-intersecting outlines in general since they can confuse
26 mf2pt1's algorithm to get the orientation of a closed path. Note that
27 MetaPost's implementation of the `turningnumber' primitive (which would
28 immediately give the orientation of a path) is severely broken before
29 version 1.0 of MetaPost, thus some hand-made code in mf2pt1.mp is used
30 to work around this bug.
32 . If outlines intersect, avoid grazing intersections. In case two outlines
33 intersect in an explicitly defined point, include this point in both
34 intersecting paths to avoid problems due to rounding errors.
36 . Don't use `draw' with a polygonal pen but for straight lines (consisting
37 of exactly two points). In most cases it is quite easy to emulate `draw'
38 with an explicit definition of the outline or with `penstroke'.
40 . Don't apply transformations after calling `fill' -- for example, don't
41 mirror `currentpicture'. Instead, transform the path and call `fill'
42 afterwards. This ensures that mf2pt1 gets the correct outline directions
43 which is a necessary prerequisite for FontForge's algorithm to remove
47 Some glyph name rules:
49 . Most glyph names have the form <group>.<name>, where <group> is defined
50 with the `fet_begingroup' command, and <name> is given with
51 `fet_beginchar' (within a `fet_begingroup' block). Example:
54 . Sometimes it would be sensible to use negative numbers in glyph names.
55 However, the `-' character shouldn't be used in a glyph name. Replace it
56 with `M'. For example, write `rests.M3mensural' instead of
59 . Glyphs which exist in both an `up' and `down' version should start the
60 <name> part with either `u' or `d', respectively. Example: `flags.d3',
61 `flags.u3'. Glyphs which are neutral w.r.t. the direction, and where
62 members of the glyph group exist which have `up' and `down' versions,
63 should start with an `s'. Example: `noteheads.s0re'.
68 . Always use smooth curve transitions. Since this is difficult to see in
69 MetaFont proof sheets (which don't show the tangents) I recommend to call
72 FONTFORGE=foo mf2pt1 ...
74 (`foo' should be a non-existent program; this avoids the default
75 postprocessing). Then call FontForge to inspect the outlines.
77 . Use rounded corners.
80 Finally, some rules to assure that rasterization at low resolutions gives
81 good results. Today, this is a minor issue, but in some cases it might show
84 . Use `define_whole_pixels' and friends where appropriate.
86 . Use `hround' and `vround' consistently. A lot of auxiliary macros are
87 defined in feta-macros.mf.
89 . If a path element is duplicated or shifted, use an integer value for the
92 . Add `eps' for mirrored paths to assure correct MetaFont rasterization.
93 See the comment and the variables at the end of `feta-params.mf' for
94 details how vertical symmetry should be achieved.