Why constraints ruins material set up? I'm creating a scene with planets, and I wanted one planet to track to the camera (but not in 100% percent). But when I want to render it the "fresnel node" is acting weird. Why constraints ruined my set up, and how to avoid this?

Of course I want planet to rotate in directon of my camera, but fresnel must behave the same as before (it should outlines the object, not creating some line via center of object). I tried different constaint settings, nothing worked.

Simpler Example (both screens are from camera perspective):
The solution is to disconnect the normal input connected to the fresnel node.

The cause is the order that things get calculated. In your example the normal value is calculated to fulfil the material needs, then the constraint is applied and the result is sent to be rendered. Without the normal input, cycles uses the normals of the object during the render, which means the normals are calculated after the constraint is applied.