# How to rotate a point around an axis using a Quaternion?

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johnnyBravo    100
I want to rotate a point around an axis using a Quaternion. I found a pdf article on gamedev, though I had a bit of trouble trying implement it. Heres what I tried from the article:
Vector v(3,0,0); //the point

Quaternion q(Vector(0,1,0)*(pi/4.0)); //the rotation quaternion (axisangle)

Quaternion p = Quaternion(1, v.x, v.y, v.z); //w,x,y,z

Quaternion r = q * p * q;


I'm not sure if what I am doing is correct, and how I am to get the new position from r? Thanks

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easyBob0101    122
vector4 quat::RotateVector (vector4 v){	quat t;	t.w = 0;	t.x = v.x;	t.y = v.y;	t.z = v.z;		quat h;	h.w = w;	h.x = x;	h.y = y;	h.z = z;		quat p = h * t * h.Conjugate ();	vector4 a ( p.x, p.y, p.z );	return a;}

That's how I do it.

-Chris

Is there no [ code ] tag here? EDIT: source...Ok. Thanks.

[Edited by - easyBob0101 on March 21, 2007 10:10:37 AM]

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johnnyBravo    100
the tags called 'source'

Thanks!

I love quaternions, I didn't realise it was so simple to rotate a point :)