DirectXTex uses WIC's IWICBitmapScaler object to resize images and to generate mipmap chains. WIC only supports "Clamp" filtering modes, so this doesn't always result in a properly tileable texture.
This would add TEX_FILTER_FLAGS for TEX_FILTER_MIRROR_U, TEX_FILTER_MIRROR_V, TEX_FILTER_MIRROR_W, TEX_FILTER_MIRROR to be supported by GenerateMipmaps[3D]().
Comments: ** Comment from web user: walbourn **
This would add TEX_FILTER_FLAGS for TEX_FILTER_MIRROR_U, TEX_FILTER_MIRROR_V, TEX_FILTER_MIRROR_W, TEX_FILTER_MIRROR to be supported by GenerateMipmaps[3D]().
Comments: ** Comment from web user: walbourn **
For POINT and BOX, LINEAR vs. MIRROR are not relevant.
For LINEAR, MIRROR is the same as clamp.
For CUBIC, WRAP vs MIRROR vs. CLAMP are distinct. That means I should have both after all.