Limitations of the ViRGE chip:

The S3 ViRGE driver has a few limitations that are a result of the limitations
of the chip itself, or are a result of insufficient documentation:

- Texture wrapping cannot be disabled in the current driver version. It is
  uncertain whether this is a feature of the chip or not.

- Most of the alpha blending modes are not supported. There is no
  source or destination function, and only texture values can be used
  for transparency.

- There is no difference between magnification and minification filtering.
  Filtering of textures is for magnification, mipmapping for minification.
  Trilinear filtering is possible, though.

- Only linear interpolated fogging is available. All other modes are rejected.
  You may override this with the variable Warp3D/ViRGE/Fog. If set to "linear",
  linear fog is accepted. If set to "all", all fogging is accepted. All other
  values only allow interploated fog.

For more details, refer to docs/Warp3D_User.guide.