Vuforia + GrabPass() in Shader in UNITY 4.5

Hi,

I was using vuforia, not for AR, but just to get the live background video working and everything was working fine until UNITY 4.5.

In my app, I have a plane between the camera and the background video. This plane is assigned a transparent shader that distort the background a little bit (it's a patterned glass).

For my shader, I use a GrabPass() in a Vert/Frag shader and I simply perturb the coordinate based on the normal map that is entered. I think the code is not the problem, the problem is since UNITY 4.5 (actually 4.5.3f3 and the code hasn't changed) my GrabPass return me a full black texture instead of the background (the live video).

This is all I found on the internet and it does not solve the problem..

At first I thought that the shader used in vuforia was rendered after my shader but it's not the case (I've check the renderQueues). I've search the internet and found nearly nothing on that subjet. Is there anyone that can help me ?

I posted the same thread in the vuforia forum some days ago and I got nothing else on this..

Thanks

 

no one has experienced this weird problem ?

I retried with the latest version before 4.5 (eg 4.3.4) and it works well but as soon as I go above 4.5 (even with the latest 4.5.4) there's nothing I can do to get my GrabPass working properly.