How to have a radiance material with two different side?

Hi all,
I don’t really know how can I have a radiance material which has two different sides? for example how to define a fabric which in one side is more reflective and has a different color from the other side? like the available fabric with this quality?

Thank you in advance for your response.

BRTDfunc might work for diffusing surfaces. The image below shows a box with single surfaces that has different colors on forward and backward directions.

void BRTDfunc someMaterial
10 0 0 0 0 0 0 0 0 0 .
0.5 0.2 0.2
0.2 0.2 0.5
0 0 0

You will get a more definitive answer to this question on the Radiance forum:


Thank you for your response, still I have another question, would you please guide using this method (this code) in honeybee radiance material component?