[yt-users] custom opacity transfer function in volume rendering

[Wolfgang Kastaun]

Hi again,

Is there a way to specify the opacity transfer function and the colormap 
for volume rendering independently? I am looking for something like 
cam.transfer_function.map_to_colormap(), but allowing me to specify a 
transfer function for the opacity myself, independently of the transfer 
function for the colormap.

What I am trying to achieve with that is the following: a field below a 
dynamically chosen cutoff should be completely transparent, so that I 
can always see the structure of the field where it is strongest, no 
matter what the absolute strength is. The color on the other hand should 
depend on the absolute value. E.g. I want to make a movie where I see 
the structure of the strongest parts of a field, unobstructed by the 
rest, but with a color that changes together with the absolute field 
strength.

Cheers,
Wolfgang.