Direction between 2 Vectors

[Colin]

OK so i have 2 3d vector's

the first is the camera and the second is an object i want to look at, my camera system using the mouse relative position so rot.x = rad offset from 0.

So i've been trying to come up with a function to calculate the Radians from vec1 to vec2 and I just can't seem to get anything to work, can anyone save me from this task as my head is about to explode.

I have the xz rotation working fine using: rV.x := ArcTan2( targ.z - posZ, targ.x - posX ); - altho sometimes it does a full rotation reversal

but i need the y axis also to be correct, looking up or down at the object once it is facing it