# Changing Typeface of Part

How do you change the typeface used for the part environment to an Opentype font?

(In the MWE below, I've used a TrueType font, but the method should be the same).

It appears the standard titlesec method for chapter and section headings doesn't work.

Engine is LuaLaTeX.

M(n-)WE:

\documentclass[11pt, a4paper]{book}
\usepackage[raggedright]{titlesec}
\usepackage{fontspec}

\newfontfamily\partfont{Verdana.ttf}
\titleformat*{\part}{\partfont}

\newfontfamily\chapterfont{Verdana.ttf}
\titleformat*{\chapter}{\chapterfont}

\begin{document}
\part{Hello world.}
\chapter{Hello again, world.}
\end{document}


The \part command can't be changed using the “easy” mode. When you compile your code you get this error:

! Package titlesec Error: Not allowed in easy' settings.

See the titlesec package documentation for explanation.
Type  H <return>  for immediate help.
...

l.7 \titleformat*{\part}{\partfont}

? h % < I typed h<return> here
The sectiong command you are trying to redefine
is not handled by the starred variant (eg, \part)
?


You'll have to use the general form of the \titleformat macro (i.e. without the *) and replicate the \part command from book class. Use this \titleformat:

\titleformat{\part}
{\filcenter\huge\bfseries} % Format of the section header
{\partname\nobreakspace\thepart} % Format of the “Part X” text
{0pt} % Horizontal space (none, we want vertical)
{\\\vspace{20pt}\Huge} % Commands before the title part (vertical space of 20 pt and increase in font size


The \chapter command allows you to use \titleformat*, so your code works.

Now you just have to add in your custom font. I used TeX Gyre Termes for I don't have Verdana.ttf:

\documentclass[11pt, a4paper]{book}
\usepackage[raggedright]{titlesec}
\usepackage{fontspec}

\newfontfamily\partfont{Tex Gyre Termes}
\titleformat{\part}
{\filcenter\huge\bfseries\partfont}
{\partname\nobreakspace\thepart}
{0pt}
{\\\vspace{20pt}\Huge}

\titleformat{\chapter}[display]
{\normalfont\huge\bfseries}{\chaptertitlename\ \thechapter}{20pt}{\Huge}

\newfontfamily\chapterfont{Tex Gyre Termes}
\titleformat*{\chapter}{\normalfont\huge\bfseries\chapterfont}

\begin{document}
\part{Hello world.}
\chapter{Hello again, world.}
\end{document}
`