Question

 void my_cool_function() 
 {
   obj_scene_data scene;
   obj_scene_data *scene_ptr = &scene;
   parse_obj_scene(scene_ptr, "test.txt");
 }

Why would I ever create a pointer to a local variable as above if I can just do

 void my_cool_function() 
 {
   obj_scene_data scene;
   parse_obj_scene(&scene, "test.txt");
 }

Just in case it’s relevant:
int parse_obj_scene(obj_scene_data *data_out, char *filename);

Answer 1

In the specific code you linked, there isn’t really a reason.

It could be functionally necessary if you have a function taking an obj_scene_data **. You can’t do &&scene, so you’d have to create a local variable before passing the address on.