Math melts my brain

May 22, 2008

SL rotations have been quite mysterious to me. Their specific relevance to me is in the fact that they are used as a llSitTarget parameter. In my studying of them (and related topics) I have learned what radians are, and grads, and the relationship between radians, grads, degrees and your garden variety circle. I am beginning even to glimpse why rotations are used in SL instead of just using degrees in a normal vector (I mean, I understand vectors), though I have no idea what gimbal lock is.
My understanding of SL rotations, as given in the LSL wiki is thus: The rotation is composed of four floats. The first three floats can be thought of as a vector, which I guess means that, in essence, they are a vector. So those first three floats describe, in radians, a direction in space. One radian is equal to 180 degrees divided by PI, or 57.296 degrees.
The first trick is to understand what a radian is and how to use it. Then to know that the fourth float describes a rotation around the direction (as an axis?) described by the first three.
These are all the words. I have yet to put them together into a clear mental picture of how a rotation works. Bah! This is all just an invention anyway, to help us understand why the toast always lands jam side down.


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