by abstrax » Tue Mar 07, 2017 11:13 pm
abstrax
Tue Mar 07, 2017 11:13 pm
It is not possible to encode colour information into an alpha channel, because it's greyscale only. Due to this fact you can't alpha blending work like a coloured filter, which would be required to be able to incorporate the absorption and transmission colour into the render result. -> We are ignoring it and only reflections are recorded.
What the option "affect alpha" does is separate reflection paths from refraction paths and averaging all reflection paths with an alpha value of 1 and all refraction paths with an alpha value of 0. So if 30% of your paths enter the specular material (i.e. are refracted), the alpha value will be 70%, because 70% of the paths get reflected.
There should be no difference in renderings between different versions. Let us know if you see differences or incorrect results.
In theory there is no difference between theory and practice. In practice there is. - Yogi Berra