Version: 2018.4
public TransparencySortMode transparencySortMode ;

説明

ソートモードの透明オブジェクト。

By default, perspective Cameras sort objects based on distance from Camera position to the object center; and orthographic Cameras sort based on distance along the view direction.

If you're making a 2D game with a perspective Camera, you might want to use TransparencySortMode.Orthographic sort mode so that objects are sorted based on distance along the Camera's view.

参考: TransparencySortMode enum、opaqueSortMode