add CBA_fnc_randomVector3D

[commy2]

When merged this pull request will:

• adds a function to generate a random 3 dimensional unit vector with uniform spherical distribution
• I see a lot of people struggling with this, implementing non uniform distributions and it bothers me...
• used in ACE in multiple places now (as macro) i.e. https://github.com/acemod/ACE3/blob/master/addons/hot/script_component.hpp#L19-L24

[PabstMirror]

distribution doesn't look right

edit: what about vectorNormalized [-1 + random 2,-1 + random 2,-1 + random 2] (it technically could fail but the odds are very slim)

[commy2]

vectorNormalized [-1 + random 2,-1 + random 2,-1 + random 2]
This is not uniformly distributed. It will bias towards where the 8 edges are of the cube.

You would have to discard all results that lie outside the sphere first (vecMag > 1) and reroll in that case before normalizing.

The problem with my math was that elevation went from 0° to 180° instead of -90° to 90°. I fixed it. Please test with that script of yours.

[PabstMirror]

looks good now