ミップマップレベルを使用するかどうか
When set to true, rendering into this render texture will create and generate mipmap levels. By default
render textures don't have mipmaps. This flag can be used only on render textures
that have power-of-two size.
By default the mipmaps will be automatically generated. If you want to render into texture mip levels manually, set generateMips to false.