How to rotate a vector to make it tangent

[redpeak]

I created @v, which is a random vector in sphere.

How do I rotate this vector to make it tangent to the sphere?

Thanks!

rotate_vector.hiplc

[toadstorm]

You can do this with two cross products.

First you take the normal, and cross it with v to get a vector orthogonal to both N and v. Then you cross that vector with N again, to get your original vector, but now orthogonal to both N and the other vector you already generated; this means it'll be tangent to your sphere.

vector tmp = cross(v@v, v@N);
v@v = cross(tmp, v@N);

Also, make sure your v@v attribute you're creating has three components, not two.

[redpeak]

Thank you very much.
I was able to create the vector that I wanted.