纹理各项异性、滤波

关于纹理滤波，lod设置
https://msdn.microsoft.com/en-us/library/bb509678%28VS.85%29.aspx
https://msdn.microsoft.com/zh-cn/subscriptions/downloads/bb509680.aspx
https://forum.unity.com/threads/tex2dlod-vs-tex2dbias.249140/
https://blog.csdn.net/lyf8068353/article/details/53408850

https://answers.unity.com/questions/310352/texture-mipmap-distance.html

https://docs.unity3d.com/ScriptReference/Texture2D.SetPixels.html 在图片导入时，进行设置，写到editor里面