Up Vector for Particles Help ( Newbie)

[Mogul4200]

I've been looking all over the place to find a way to make my particles have an up vector perpendicular to the normal it is on. I have the particles flowing around a sphere. I have seen many solutions for this type of thing, but I'm too new to implement this for my situation. 

Thank you for the help. 

 

particlesFlow.hip

[StepbyStepVFX]

Mathematically speaking, you have an infinite number of vectors that are perpendicular to a given vector. To chose one of them, you usually use a second vector, and make a cross product between your two vectors. The vector you obtain is perpendicular to the two firsts and is unique.

So what you can do is do a cross product (in a POP Wrangle, with VEX function cross(vector 1, vector 2)), and use the normal and a second vector.

I don't know how your normal was build, but when I need to create a frame of vectors on particles, I like to use :

v@up = {0,1,0};

@N = normalize(@vel); (if velocity  != 0)

Then i do the cross product on those 2 vectors, but in my case, up vector is... up :-) So I am not sure if that helps you...

Maybe what you need is :

vector3 tempup = {0,1,0}; (temporary up vector)

vector3 tempz = cross(normalize(@N), v@tempup); (and you can set @N to be normalized speed, if you want, like example above)

v@up = cross(@N, v@temp);