ahh thanks! a missed info. I can do that mipmap generation on texture editor initialization.

they are pre-made textures, 4 textures are combined into one, to easily access 8 textures from the terrain shader as 4 entity and 4 material skins (global color map, global normal map, rgba blendmap1, rgba blendmap2, 1st 1x4 color map, 1st 1x4 optional normal map, 2nd 1x4 color map, 2nd 1x4 optional normal map), but I could make 2x2 arrangement instead of 1x4, but with Gimp it is easier to create 1x4.