Local Rotation Orders

Good video from Guerilla CG, helps remind me of the important things to think about with LR Orders every time. To remember:

When you have a rotation order, for example xyz, is like a hierarchy where z is the parent with y as a child of z, and x is a child of y. So we first have z evaluated, which affects y and x, then y is evaluated, which affects x, then x is evaluated on it’s own. (It’s reversed!)

With all 6 possible LRO combinations, gimbal lock happens when the middle axis y moves (usually 90 degrees), because it only affects one axis (x) it can rotate so that z and x line up and become gimbal locked. To find the most suitable order, we have to think about how our joint will be moving.

The last axis (z in xyz) will carry the other 2 axis with it. The most important axis should go there, the least important axis should be on the most left. The middle axis should be the least used axis, as its rotation can cause gimbal lock.

If you’re rotating/orbiting a character around an axis, current example being the Y axis, then it is important that the y axis carries the x and z to ensure that the character can bend forward and backwards; so y must be the first axis in the order (so either zxy or xzy)

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