From Valve Developer Community
$dudvmapis now defunct and is replaced by the
Refractshader. Though, the
Watershader still uses a du/dv map for
Creating a du/dv map from a normal mapA du/dv map can be easily created from a normal map in just two steps. You can also do this if you don't want to bother with the nVidia tools.
Note:Work from the source texture (such as a .tga) if possible.
- Open the normal map and invert the colours (Image > Adjustments > Invert or + ).
- Go to Colors > Adjust > Brightness/Contrast.
- Check "Use Legacy"
- Set Brightness to -17
- Set Contrast to 100
Paint Shop Pro
- Open the normal map and invert the colours (Colors > Negative Image).
- Adjust the contrast as high as it will go.
You now have a finished du/dv map. When converting to a VTF, set the format to UV88.