Tformvector help

I need to transform a vector in worldspace to the coordinate system defined by another vector.
The standard tformvector function only works with entities.

Well, what coordinate system is your vector in?

it is in worldspace

I mean what coord system is your 'destination' vector in?

the dest coordinate system is defined by a vector instead of a destination entity like in tformvector function.
Sorry maybe I'm not so clear :)

Well, your dest vector must be in one coord system or another. :)

Use a helper pivot and align it to the vector and then tformvector

;assume d.vector3 is destination
;assume w.vector3 is the world vector
;assume n.vector3 is the new vector

global HelperPivot = createpivot()

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.
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aligntovector HelperPivot, d\x, d\y, d\z, 3
tformvector w\x, w\y, w\z , 0 , HelperPivot
n\x = tformedx()
n\y = tformedy()
n\z = tformedz()

You could also use Dot product for this.

Stevie

I'll explain my problem in detail :)
I have my particle system where the emission dir is defined by the Z vector(-1) and use random XY (rnd(X,-X),rnd(Y,-Y)) to modify the emission cone.

Suppose I need the emission cone direction aligned to a vector that is pointing to the right; this way XY should become ZY.

The fastest way to transform XY to ZY ?