Here testing a series of four possible combinations of the two most obvious factors; #1 the Brep/Mesh and #2: Two different Transforms (my old transform and a new transform created near the test setup).
I connected the "“My” old transform directly to its source (hence the wire going out of sight to the left) without any hops to ensure that hops doesn’t disturb the data).
Image A: “Your” Brep/Mesh + New Transform == Both Meshes OK.
I just had a similar issue with some curves. Took a long time tot figure out hat the problem was, but for some reason, a few curves after a transform became invalid. Workaround: test for validity, explode non-valid curves, join segments, test again
Meshes are not treated the same way in V7 so now there are lot invalid meshes that were not invalid mesh in previous version. There are some discussions to heal meshes. I used a little script to do that.
But in order for McNeel to resolve the problem please post a little script with a faulty mesh.
Same mesh, different orientations.
Both valid and invalid, but the mesh is the same.
This is a bug depending on cartesian transformations, and the fact that some other meshes are working correctly is not enough to say the opposite. Nice crocodile btw.
The main thing to say is that the orientation of a mesh can not determine wether it is valid or not, because it’s just a change of basis.
Sometimes I use the “mesh brep” component (usually with a low number of triangles), other times I start picking a mesh from a library (robots library in the case of the robot above)…I almost never start from native meshes.
But I would like to point again that the problem is the combination of mesh + transformation.