Hi everyone
A strange thing that I have encountered is the following which can possibly be a bug
Importing a normal map that has an alpha channel gives this result in UnrealEngine
And one that hasn’t got an alpha channel gives this result
Both normal maps are based on the same height map.
Both normal maps are created with xNormal
The only difference is that the second one has unchecked “Bias” Property in the xNormal tool therefore not having an alpha channel
Hi gogata258 -
What you are seeing is how the engine processes PNG Alpha’s which function the same but are stored differently bit-wise than a TGA Alpha. With a PNG, the Engine does not keep the pixel information for the RGB channels where the Alpha Channel says it is not needed. With a TGA, the engine adds Alpha Channel information but also keeps the RGB Channel information for all pixels. This is the sole reason that PNGs typically are of a smaller file size than a TGA.
If you need an Alpha Channel for your Normal, I would either move the Alpha to another texture or save as a 32 bit TGA file which will allow you to save the RGB Channels uneffected.
Thank You
Eric Ketchum
