We've been using Vuforia for a while now in conjunction with the Projected shadows script http://wiki.unity3d.com/index.php?title=Character_Shadow
In the past we have had no problems with this, Unfortunately the other day we found we had to update vuforia to the latest version to remove the UDID issues for appstore submition. Doing so has broken our shadows :(. Now whenever the shadow is active, what should be the camera background becomes an almost solid black with ghosting images of the 3D scene content trailing as you move the camera. The second the shadow script is disabled by looking away from the target, the issue is fixed.
I've been trying to work out whats going wrong with this, the closest I've come so far was that the camera used in the project shadows was set to the same depth as one of the cameras that the QCAR camera generates. However when i set the projector camera to use a depth that no other camera was using the issue still remained.
It looks like something has changed perhaps with clear flags or something between various rendering steps. But I've not managed to find it yet. The reason we're using this projected shadows script is that A) this project is still in unity 3.5 and not 4. and B) Even though 4 supports realtime shadows on mobile, the shadows it produces are not as nice as those produced by this projector script setup for our needs.
Has anyone else had these issues, or similar ones? Can anyone sugest somewhere to look to find the cause of this problem? Any sugestsions or help are greatly appreciated.