Generating blue normal map channel from red and green channels I have a normal map texture where the blue channel is used to store some other map of information since it is normally used in a program which calculates the blue channel from the red and green channel automatically. Now I want to use that same texture in Blender and figured it shouldn't be too hard to do the math in the node editor so it jus works regardless of which normal map I use. However, it doesn't seem to work. The result I get has shading issues quite similar to how it looks without any information in the blue channel. This is despite me having found the formula and I believe created it accurately in the node editor. Does anyone have any idea why this wouldn't create the desired results? 

The formula I found to generate the blue channel is "B = sqrt(1 - ((R * R) + (G * G)))"
I managed to generate the Z channel in the normal map according to this scheme (taken from UE4). In the &quot;normal&quot; texture, everything is as usual, only the Blue channel, replaced by roughness.