restoring a sharp corner on t-spline surface

[Anonymous]

I have a t spline surface that resulted from converting an obj file, and I wish to have four sharp corners on it.  In the box view it has sharp corners (see upper left corner) but in 'smooth view' it has become rounded.  I realise there is a triangle here but my attempts to insert an edge or a vertex and make a quadrangle at the corner have failed miserably and resulted in a very distorted form.  I'm at a loss as to how to edit this, please help!

[jeff_strater · Accepted solution]

Box view always shows just the "unsmoothed" lattice of the TSpline.  The smooth version shows the smoothed (similar to Sub-D surfaces) version of the lattice.  

If you want to maintain sharp corners on any edges, use the Crease command on those edges.  This suppresses the smoothing on those edges:

[Anonymous]

Hi Jeff,

thanks for that prompt response.  I had tried using the 'Crease' command previously and it didn't seem to work.  I think I was picking the wrong edges - when I select the edge pointing towards the corner (rather than those adjacent to it) it does indeed work.  That bit wasn't obvious to me.

thanks again

R