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.