Couple questions:
You say "Note that there are no shared vertices on each tile". So each tile mesh is made up of a set of unwelded tris, yes? Can I ask why? :) UpdateNormals can't smooth normals unless shared verts are used.
If each of the tile meshes normals are correct before you're AddMesh'ing them together, why are you using UpdateNormals at all? You do know AddMesh doesn't weld any vertices, right?
Last thing - you may have seen this already - but this may help with 'debugging' your normals, at least :)
http://www.blitzbasic.com/codearcs/codearcs.php?code=1085
You say "Note that there are no shared vertices on each tile". So each tile mesh is made up of a set of unwelded tris, yes? Can I ask why? :) UpdateNormals can't smooth normals unless shared verts are used.
If each of the tile meshes normals are correct before you're AddMesh'ing them together, why are you using UpdateNormals at all? You do know AddMesh doesn't weld any vertices, right?
Last thing - you may have seen this already - but this may help with 'debugging' your normals, at least :)
http://www.blitzbasic.com/codearcs/codearcs.php?code=1085