I'm *very* new to ConTeXt, so please excuse the newbie question. I'm trying
to load a font from a file. The .otf files are stored in a directory named
fonts/ which is in the directory of the .tex file I'm trying to compile.

This code does not work, and reverts to the default font:

\definefontfamily [mainface][serif] [My Font]
                  [tf=file:./fonts/MyFont.otf,
                   it=file:./fonts/MyFont-It.otf,
                   bf=file:./fonts/MyFont-Bd.otf,
                   bi=file:./fonts/MyFont-BdIt.otf]
\setupbodyfont[mainface]
\starttext\title{Hello, world!}

Hello World! \emph{Hi!}
\stoptext

However, if I copy the .otf files into the same directory as the .tex file,
and write tf=file:MyFont.otf etc, then everything works fine.

How do I specify a relative path to the font, inside the .tex file?

In LaTeX, I would use fontspec package and do the following:

\setmainfont {MyFont.otf}
             [Path        =./fonts/,
              ItalicFont  = MyFont-It.otf]

However, I couldn't find the equivalent syntax for \definefontfamily in
ConTeXt.

Just to mention, I am using ConTeXt version: 2019.03.21 21:39 as part of
TeX Live, on Manjaro Linux.

Regards,

Krešimir