parametrized surface and surfacecolor / fill_z

[dorn-gerhard]

I would like to plot a parametrized surface (like a torus)
[u,v] -> [x,y,z]
coloring the surface according to another function
[u,v] -> c

I tried surface(x, y, z, fill_z = c) but the fill_z argument is ignored.

Compare https://plotly.com/julia/3d-surface-plots/#setting-the-surface-color

It's interesting to observe that fill_z also can throw an error when using
vectors for x and y and a matrix z of dimensions length(x) times length(y) or a function:
x = range(-3, 3, length=30)
surface(x, x, (x,y) -> exp(-x^2-y^2), fill_z = x * ones(size(x))' )

I also tried the display_option feature in the documentation
which seems to work for x, y parametrized surfaces (x,y)->z only
e.g. using a light source:
surface(x,x, (x,y) -> exp(-x^2-y^2), display_option=6)
Here I couldn't figure out the syntax to adopt the surface color individually (option 4 or 5?).

Maybe there is a best practise to color parametrized surfaces individually