Re: quaternion question

[James W. W. <os...@jw...>]

On Feb 23, 2005, at 11:02 PM, Keith Wiley wrote:

> I have an object that has not been rotated at all yet, so its starting 
> quaternion Q is (1,0,0,0).  I have a vector V (x,y,z) that specifies a 
> 3D pointing or facing direction.  I would like to take the object's 
> facing direction, which starts out (0,0,1), straight down the z axis, 
> and orient it such that it faces in the same direction as the vector 
> V.  I realize this doesn't entirely specify an orientation since there 
> is still the question of how the object is "rolled" around the facing 
> vector, but I am not concerned with that right now.  For this specific 
> application it doesn't even matter because the object in question is 
> perfectly cylindrical around the z axis so rolling doesn't mean 
> anything.  I just want to make it point in the direction of the vector 
> V.
>
> How do I do this?  Any ideas?

How about using Q3Quaternion_SetRotateVectorToVector?
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