Buy Modo 601 or not?

 From:  Michael Gibson
5593.10 In reply to 5593.8 
The plug-in for Blender is for an older version, if I remember right there was a major change in the plug-in interface in Blender 2.5 and the older LWO import plug-in that Anthony wrote that would bring in vertex normals does not work anymore with the new plug-in interface. And as mentioned above, getting imports to work with vertex normals is only part of the problem - Blender does not use the model's actual current vertex normals when it does a render, it throws them out and calculates a new set just from the polygon data. It will also throw them out if you go into edit mode even if you do not do any operation that would actually invalidate them (like just editing UVs for example).

So Blender has problems with vertex normals handling on multiple levels. Anthony did make a custom version of Blender that had all these things disabled - but it is again an old version and his patch was not accepted into the Blender main version. You can find this customized old version here:

There is a detailed previous discussion about this on the forum here:

This is a major problem with Blender that makes it difficult to use CAD-generated data (basically from any CAD program also including MoI) with Blender.

If you are doing only polygon modeling it's not such a big problem since the vertex normals in that case are usually already coming from the polygon data in the first place. It's when you want to use CAD data where the vertex normals are coming from the original CAD data and creating them from the polygons only does not work very well that it causes problems.

- Michael