Blend Shapes

The cat needs to be able to sleep and therefore shut it eyes. To do this I have been looking into blend shapes. I remember a brief lesson on blend shapes in the first year so I know that I had to create a separate model with the desired action on it (i.e a model of the cat with its eyes shut).

I used reference images and managed to model one eye shut that looked quite cat-like.

It did take me several attempts so rather than having to model the eye shut on the other side of the face too, I deleted half the face and mirrored the geometry so that they would be exactly the same. 

With this model with the shut eyes I tired to create a blend shape. This was the outcome:

Firstly I tried to delete the history and freeze transformations to see if that made any difference but it was still the same. I tried exporting the model with the shut eyes as a .obj file and then reimporting it to see if that would solve the problem but it was still the same.

In the end I turned to the internet and researched the issue. I came across a forum where someone mentioned that the topology and vertex order had to be the same or similar for the blend shape to work.

In a book I have been reading called "Mastering Autodesk Maya" by Eric Keller there is a small section about importing without any vertex order being disturbed by using the option box when importing. So I tried to reimport the model without disturbing the vertex order.

It wasn't until I had tried all of these methods that I realised that mirroring geometry would probably mess up the vertex order, especially when I was sewing vertices back together around the head and neck.

This mad me realise that I would have to start again so duplicate the original mesh (with the open eyes) and model each eye closed separately rather than using shortcuts and mirroring the geometry. This did take longer but it also allowed me to shut the eyes independently whereas before I was going to have only one control to shut both eyes. It has also meant that the topology and vertex order has stayed the same or similar to the original model.

I added attributes so that I could control the blend shapes in the channel box and created the blend shapes. This then worked straight away without any problems.