Du/dv map

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Note:$dudvmap is now defunct and is replaced by the Refract shader. Though, the Water shader still uses a du/dv map for $bumpmap.

du/dv maps are used for DirectX 8 refractions. If you're a Photoshop user, it's easy to create du/dv maps using nVidia's texture tools.

Creating a du/dv map from a normal map

A 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.

Photoshop

  1. Open the normal map and invert the colours (Image > Adjustments > Invert or Ctrl+I).
  2. Go to Colors > Adjust > Brightness/Contrast.
    1. Check "Use Legacy"
    2. Set Brightness to -17
    3. Set Contrast to 100

Paint Shop Pro

  1. Open the normal map and invert the colours (Colors > Negative Image).
  2. 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.

See also