Solved the font problem: The hashing scheme described in the docs does evaluate the paths at compile time, which is usually the development machine’s paths and not the deployed (nerves) one.

I “fixed” it for now by differentiating a bit more and hardcoding the nerves path (bad!):

  @font_hash_path :code.priv_dir(:my_app) |> Path.join("/static/fonts/myfont.otf")

  if @target == "host" do
    @font_path @font_hash_path
  else
    @font_path "/srv/erlang/lib/my_app-0.1.0/priv/static/fonts/myfont.otf"
  end

  @font_hash Scenic.Cache.Hash.file!(@font_hash_path, :sha)

and in init/2

def init(_, opts) do
  Scenic.Cache.File.load(@font_path, @font_hash)
...

I guess thats also the problem with the built-in fonts not showing in nerves

Just published scenic_driver_nerves_rpi 0.9.2 to hex.

This fixes the issue where the default font was not rendering on the Raspberry Pi via Nerves.

@axelson Yes you are right. The canonical examples try to build the graph at compile time for performance and other reasons. And hashing resources like custom fonts at runtime does not feel right.

@thovoll Nice! I also discovered that using really large fonts (>500) crashes the renderer on the RPi. It is also having a hard time on the desktop where all textures are wrong for a second after starting up. Also, line breaks in the text suddenly appear when using large fonts. (for example, rendering a screen-filling clock on a 1920x1050 display).

All in all, small things that can be resolved. I really like Scenic, thanks @boydm !