How does exporting a hierarchical model to obj manage coordinates? I'm debugging an .obj parser a colleague of mine wrote for a simple Lua game, and I'm having trouble with understanding something. Since the .obj file does not preserve the tree structure I create in a Blender model, but only has the separate objects (the o wheel-like lines), how are the coordinates treated? Let's say I have wheels as children of a car's chassis in Blender, the car is translated from the origin and the wheels have a relative translation, rotation and scale from the car to be in the appropriate position. If I export them to .obj, are the coordinates of their vertices recalculated as global ones (meaning they already are where they should be if I put both the chassis and the wheels in as separate objects) or are they in relative coordinates (meaning I have to recreate the parent-child relation to have them in the right place)?
The .obj format is very simple and stores all vertices in global coordinates. It can't be local coordinates because there is no definition of a world matrix per object in the file format, which would be required to perform a conversion from local to global coordinates.