Vector to Rotation

[SpiderPig]

How would I transform the following (or any other) vector to a 3D rotation without using a pivot as a buffer?  Can the Transform functions be used here or have I already found the easiest way?  Calling on any math guys out there...

upDirection = Vec3(0.0f, 1.0f, 0.0f);
pivotAlignment->AlignToVector(upDirection, 1);
Vec3 _rot = pivotAlignment->GetRotation();			//_rot = Vec3(0.0f, 0.0f, 0.0f);
physicsParent->PhysicsSetRotation(_rot, 1.0f);

I don't want to use a pivot because, well, it just seems ugly.

[Josh]

The difficulty here is that a vector does not describe a 3D rotation. You need another term for roll, and your vector you used above demonstrates the exact problem, since it points straight up.

Mat4 mat;
mat.MakeDir(x,y,z)
Quat rotation = mat.GetQuaternion()

Note this will still have problems when pointing straight up.

[SpiderPig]

Thanks.  So those problems wouldn't exist with AlignToVector() or Point()?  ?

[Josh]

Those use the same code internally as this.

I'm not sure. The routine might just consider 90,0,0 to be "up" rotation. It will probably work okay. But just know that the engine is making a decision for you because the problem does not have one solution.

[SpiderPig]

Okay thanks, I'll see how it goes.  If it doesn't work well I'll try making a predefined list of rotations for each of the gravity directions.