I would like to plot a 3D structure representing the stomach in Matlab. A sketch of what it should look like is here: http://thoracicsurgery.stanford.edu/patient_care/images/normal-stomach.jpg
Still, I do not need an accurate reproduction of the stomach. A rough one will do the job.
I tried looking into the patch function, but I could not find any suggestions for complex structures. The question is: can you provide me with an example of a similar 3D patch built using vertices and faces?
I was thinking of piling up a series of circles of different centers and radii, but I would need some help in the setup.
You'll need a "spine" for the circles. Then you'll need to put some "ribs" on the "spine". (Here the spine is the locus of centres and the ribs are the circles.) Do you want the "ribs" to be parallel to one another, or do you want them to be at right angles to the direction of the "spine"?
The spine could be parametrised by $\sigma(u) = (0,0,u)$ and the ribs by $\rho(v) = (r\cos v, r \sin v,0)$ where $r$ is a function of $u$. The "ribcage" would be given by $$(r(u)\cos v, r(u)\sin v, u)$$
This assumes that the spine is the $z$-axis and that the ribs are all horizontal.
You could play about with the centres, i.e. change $\sigma$, and play about with the radius function $r$.
You would probably need the locus of centres to trace out a curve.