Resolve reletive paths relative to the launch script

This means that require "thing" now works

lua/wrap/stdio.cpp

@@ -4,6 +4,8 @@
 
 #include "engine/file.hpp"
 
+extern std::string base_path;
+
 // wrap stdio funcs around blit:: funcs
 wrap_FILE *wrap_stdin = nullptr;
 wrap_FILE *wrap_stdout = nullptr;
@@ -44,8 +46,14 @@ wrap_FILE *wrap_fopen(const char *filename, const char *mode)
             blit_mode |= blit::OpenMode::read;
     }
 
+    std::string filename_str = filename;
+
+    // adjust relative filenames to root
+    if(filename[0] == '.' && filename[1] == '/')
+        filename_str = base_path + (filename + 1);
+
     auto ret = new wrap_FILE;
-    ret->file.open(filename, blit_mode);
+    ret->file.open(filename_str, blit_mode);
     ret->offset = 0;
 
     ret->getc_buf_len = ret->getc_buf_off = 0;

main.cpp

@@ -8,6 +8,8 @@ lua_State *L;
 bool has_update = true;
 bool has_render = true;
 
+std::string base_path;
+
 void init() {
     set_screen_mode(ScreenMode::lores);
     screen.pen = Pen(0, 0, 0, 255);
@@ -20,9 +22,18 @@ void init() {
     lua_blit_update_state(L);
 
     auto launchPath = blit::get_launch_path();
+
     if(!launchPath) {
         launchPath = "main.lua";
     }
+
+
+    // set base path from dir of main script
+    auto pos = std::string_view(launchPath).find_last_of('/');
+    if(pos != std::string_view::npos)
+        base_path = std::string_view(launchPath).substr(0, pos);
+
+    // load the script
     auto err = luaL_loadfile(L, launchPath);
 
     if(err) {