The mipmap bias of the texture.
A positive bias makes a texture appear extra blurry, while a negative bias sharpens
the texture. Note that using large negative bias can reduce performance, so it's not
recommended to use more than -0.5 negative bias. In most cases better sharpening of the texture
can be achieved by using anisotropic filtering. Also note that mipmap bias does not work
with MaterialPropertyBlocks, and some platforms, e.g., OpenGL ES based do not support it
without custom shaders.
另请参阅：Texture.anisoLevel、texture assets。