所谓type3字体是该怎么用啊

在命令行输入:

texdoc mpfonts

这将得到：

mpfonts
Maintained by Daniel Benjamin Miller
January 30, 2020

***

The Computer Modern fonts are available in Type 1 format, but these renditions
are somewhat thin and spindly, and produce much lighter results than the
originals. It is alternatively possible to use METAFONT bitmaps, but this has
its disadvantages in comparison with vector fonts.

These fonts are conversions to Type 3 fonts, done entirely in METAPOST;
they are vector fonts which are a direct conversion from the original METAFONT
files, so they are the design most authentic to the originals.

However, these fonts, because they are PostScript Type 3 fonts, are not
suitable for on-screen reading, and should probably only be used for printing.

In order to produce a document using these fonts, first produce a DVI with
TeX or LaTeX, and then run dvips as follows:

dvips -D 10000 -u +mpfonts.map myfile.dvi

This will output a PostScript file using these fonts. It is recommended to keep
the resolution at 10000 DPI, since this allows for the most accurate glyph
positioning. As the fonts are vector fonts, this will not increase file size
in comparison with lower DPI settings.

***

The following font sets are supported:

* Computer Modern (cm)
* LaTeX fonts (latex-fonts)
* Frege symbols (fge)
* Extra logic symbols (cmll)
* Fraktur (cmfrak)
* AMS fonts (amsfonts)
* IPA (tipa)

Note that the T1 encoding is not directly supported. When using this package,
use the classic OT1 encoding (this is the default encoding, and will be used
unless you choose to change it).

丢进AI:

mpfonts
由 Daniel Benjamin Miller 维护
2020年1月30日

***

Computer Modern 字体虽提供 Type 1 格式，但这些版本略显纤细单薄，输出效果较原版更为轻淡。虽然也可使用 METAFONT 点阵字体，但与矢量字体相比存在固有缺陷。

本套字体通过 METAPOST 完全转换为 Type 3 格式，是从原始 METAFONT 文件直接转换的矢量字体，因此最大程度保留了原版的设计精髓。

需要注意的是，由于采用 PostScript Type 3 格式，这些字体不适合屏幕阅读，建议仅用于印刷场景。

使用步骤：
1. 先用 TeX 或 LaTeX 生成 DVI 文件
2. 执行以下 dvips 命令：`dvips -D 10000 -u +mpfonts.map myfile.dvi`

将生成采用本字体的 PostScript 文件。推荐保持 10000 DPI 分辨率以确保字形定位精确。由于是矢量字体，较高分辨率不会导致文件体积增大。

***

支持以下字体集：
* Computer Modern (cm)
* LaTeX fonts (latex-fonts)
* Frege symbols (fge)
* Extra logic symbols (cmll)
* Fraktur (cmfrak)
* AMS fonts (amsfonts)
* IPA (tipa)

特别说明：本包不直接支持 T1 编码，使用时请采用经典 OT1 编码（此为默认编码，除非手动更改）。

所谓type3字体是该怎么用啊

此事在「使用步骤」中亦有说明....