Launcher for the LuaJIT backend.

Looks for main.lua. Launch it like this:

    luajit myapp/lib/luigi/launch.lua

If luigi isn't inside the project directory, pass
the path containing main.lua as the second argument.
The path must end with a directory separator.

    luajit /opt/luigi/launch.lua ./myapp/

If the app prefixes luigi modules with something
other then 'luigi', pass that prefix as the third
argument.

    luajit /opt/luigi/launch.lua ./myapp/ lib.luigi

luigi/backend/ffisdl/font.lua

@@ -1,4 +1,5 @@
 local REL = (...):gsub('[^.]*$', '')
+local APP_ROOT = rawget(_G, 'LUIGI_APP_ROOT') or ''
 
 local ffi = require 'ffi'
 local sdl = require(REL .. 'sdl')
@@ -207,7 +208,7 @@ function Font:constructor (path, size)
     local key = path .. '_' .. size
 
     if not fontCache[key] then
-        local font = SDL2_ttf.TTF_OpenFont(path, size)
+        local font = SDL2_ttf.TTF_OpenFont(APP_ROOT .. path, size)
 
         if font == nil then
             error(ffi.string(sdl.getError()))

luigi/backend/ffisdl/image.lua

@@ -1,4 +1,5 @@
 local REL = (...):gsub('[^.]*$', '')
+local APP_ROOT = rawget(_G, 'LUIGI_APP_ROOT') or ''
 
 local ffi = require 'ffi'
 local sdl = require(REL .. 'sdl')
@@ -15,7 +16,7 @@ end })
 function Image:constructor (renderer, path)
     self.sdlRenderer = renderer
     self.sdlSurface = ffi.gc(
-        SDL2_image.IMG_Load(path),
+        SDL2_image.IMG_Load(APP_ROOT .. path),
         sdl.freeSurface)
 
     if self.sdlSurface == nil then