Question

I am running Octave 3.4.0 and want to create a transparent surface plot. However, I have not been able to do so when messing around with facealpha, edgealpha, alphadata and alphadatamapping.

Example code for creating a non-transparent surface:

p = peaks(40);
f1 = figure(10);clf
s1 = surface(p)
view(3)
xlabel('x');ylabel('y');
hold on;plot3([0 40],[40 0],[-10 10],'k')
set(s1,'edgecolor','none')
set(s1,'facealpha',0.2)

The result of this given in the image below. As you can see, the line drawn diagnonlly at the start is hidden behind the surface, even though the surface is suppose to be semi-transparent. Is this a bug in my version of Octave, or have I missed something?

Answer 1

This works for me on Octave 3.6.2 using gnuplot as the graphics toolkit. So you better upgrade your Octave installation.

Two things to note though:

1. the part of the diagonal line that goes behind the surface is not drawn in a lighter so it still looks weird;
2. with the new experimental fltk graphics toolkit, it doesn’t work at all.