Here is a video about unity depth shader workarounds:

http://www.burgzergarcade.com/tutorials/game-engines/unity3d/unity-ios-shaderlab-tutorial-10-1-z-fighting

also his tutorial 6.2 and 6.3 are all about depth...

and this unity resource: http://unity3d.com/support/documentation/Components/SL-CullAndDepth.html

Here is a Ton of info about it with 3 solutions:

http://software.intel.com/en-us/articles/alternatives-to-using-z-bias-to-fix-z-fighting-issues/

I have ended with a custom-non-optimal-solution that at least works for me. I add a"ZFighter" component to any GameObject which I want to get a little bit distanced from a back object/wall. This separation is calculated according to Camera distance.

1. using UnityEngine;
2. using System.Collections;
4. public class ZFighter : MonoBehaviour {
6. // Use this for initialization
7. private Vector3 lastLocalPosition;
8. private Vector3 lastCamPos;
9. private Vector3 lastPos;
11. void Start () {
12. lastLocalPosition = transform.localPosition;
13. lastPos = transform.position;
14. lastCamPos = Camera.main.transform.position - Vector3.up; // just to force update on first frame
15. }
17. void Update () {
18. Vector3 camPos = Camera.main.transform.position;
19. if (camPos != lastCamPos || transform.position != lastPos) {
20. lastCamPos = camPos;
21. transform.localPosition = lastLocalPosition + (camPos - transform.position) * 0.01f;
22. lastPos = transform.position;
23. }
24. }
25. }