I am trying to understand the issues that Blender is having with MoI meshes.

My understanding is that MoI exports vertex normals in the OBJ file. But then when Blender imports the OBJ file, it then ignores the vertex normals in the file and recalculates its own vertex normals, which can then lead to issues.

My questions are:

- Why are the calculations of the vertex normals different between MoI and Blender? I would think that the calculation of vertex normals would be the same for all 3D modeling apps.

- How does MoI calculate vertex normals?

- How does Blender calculate vertex normals?

- And does the calculation only differ for certain shapes, such as spheres vs cubes? Or curves vs flat surfaces? Or does the calculation differ for all object shapes?

- Finally, is there a way that Blender could calculate the correct vertex normals from the information that it has?