How could I a draw circle on a 2D surface in 3D?

I'd like to draw a circle on this surface around the red dot (see picture) enclosing an area where the energy is less than 2.5 kcal/mol. The surface is computed as follows:

p=patch(isosurface(X,Y,Z,W,0)); isonormals(X,Y,Z,W,p); isocolors(X,Y,Z,W,p);

Can I somehow extract the meshgrid data from this surface?

Thanks,

James

Answer 1

[Mike Garrity]

No, you probably don't want to try and force it into a quad mesh. If you look at your triangle mesh:

set(p,'EdgeColor','white')

You'll see that the triangulation that isosurface creates is pretty irregular. Anything you do to try to force it into a regular quad mesh is going to introduce errors.

I would suggest contouring your triangle mesh with this function that Duane Hanselman put on the File Exchange.