So after some searching I found out why rotation matrices(euler) work the way they do. But I can't seem to find any resources that do the same for quaternions. Like: [ cos(theta) -sin(theta) 0] [ sin(theta) cos(theta) 0] [ 0 0 1] Is a rotation matrix about the z-axis. I found alot of info on the net on how to use it, not so much on why it works. Eventually this post explained: http://www.gamedev.net/community/forums/topic.asp?topic_id=286454 Im looking for an explanation just like that but for a rotation quaternion. Q = (cos(theta/2), rx sin(theta/2), ry sin(theta/2), rz sin(theta/2)) I found alot of articles explaining how to do math with them, how they avoid grimbal lock and that the above can be used for rotating. And I can see that if I multiply my point with the above quaternion that it works, but why? :D Can someone please point me in the right direction?

My math background is from high school :)

But I did some research on complex numbers, and I found out that the original reason for the creation of quaternions was for an extension of complex numbers into 3d.

I also found out that it wasn't until later that it was found that quaternions were also useful for rotation in 3d.

I can't see the link between complex numbers and rotating a point around an vector, do you ever need the square of a negative number?. Also if I look at the rotation quaternion the complex numbers(i) are just replaced by sin(theta/2). Wich leads me to think that the rotation quaternion just uses the math "rules" from the quaternions, but has a basic explanation. No? :p

Thanks I'm fully understanding quaternions now

I found wiki to be unnecessary confusing/complex.
But an external link on the wiki page you provided had a basic high school explanation about how quaternions work. Just what I was looking for.

For anyone who is interested it makes it all VERY simple:
http://www.itk.org/CourseWare/Training/QuaternionsI.pdf

In fact the word complex(number) is not even mentioned once! :D

thanks for the link, nielzzz. I was just browsing this topic and read over that. I'm stashing that one away for sure! It's even better than what's the 3D Math Primer book.