So, you want to make a custom font atlas and

• The msdf-atlas-gen source code
  You'll need to clone this recursively, so you get the submodules:

  git clone --recurse-submodules https://github.com/Chlumsky/msdf-atlas-gen.git

• A font file in ttf/otf OpenType formats
• A C++ compiler
• Cmake
• tinyxml2 (install using your package manager, it's tinyxml2 on brew)

1. Build msdf-atlas-gen

   # In the msdf-atlas-gen folder
   # On macOS/unix-like systems:
    
   mkdir build && cd build # create the build folder
   cmake -DMSDF_ATLAS_USE_VCPKG=OFF -DMSDF_ATLAS_USE_SKIA=OFF .. # generate makefile using cmake
   make & cd bin # build and go to the output folder

2. Generate font files!

   # the magic command
   ./msdf-atlas-gen -type mtsdf -format png -csv FONTNAME.csv -imageout FONTNAME.png -font PATH_TO_FONT_FILE

3. Copy the generated FONTNAME.csv and FONTNAME.png to the vendor/fonts folder in folk
4. Edit line this line in display.folk

   # replace the "PTSans-Regular" with FONTNAME
   variable font [font load "PTSans-Regular"]