Dear all,

I managed to find a workaround that works with MatlabR2016B, maybe it can help someone with the same issue.
The most recent versions generate the vertexnormals attribute when a lighting is associated to the patch.
Without the lighting, the attribute is an empty array that produces the error reported by Max.

In my case by editing get_vertexnormals function as follows

%vnorm = - get(p,'vertexnormals');
%%%%added
light
lighting gouraud
pause(2);
vnorm=-p.VertexNormals;
%%%%%

I managed to get the t-map on the tutorial data.

Paolo