Would distance between camera and model affect shader?

I am sorry that maybe I have not claimed my question clearly. The problem is I have tried to create an outline for part of the model, but only when the camera is kind of far away from the model would the outline display. If I move closer reaching a certain distance, the color would disappear.110526-微信截图-20180201151955.png

110527-shader1.png

Finally, what I did was changed “Queue = Geometry” to “Queue = AlphaTest” in shader and everything works, but I still don’t know the exact reason.