Rotation by texture

[Mnietek]

How can I control rotation of particles by texture? I'd like to rotate particles in local space on custom axis by texture value.

[tyFlow]

You can use a Script operator to sample the texture, then translate to rotation in whatever way you want. There's not a built-in way to do it because there's no standard way to convert a texture value to a rotation value.

[Mnietek]

You can use a Script operator to sample the texture, then translate to rotation in whatever way you want. There's not a built-in way to do it because there's no standard way to convert a texture value to a rotation value.

Thanks for the answer.
I found example file here: https://www.youtube.com/watch?v=vOls8gYcDrc.
File attached.
This is good startint point to my investigations.
Everything is clear except one thing:
why are there two operators that first read the rotation, write it to the custom channel, and then read that value from the custom channel and set the rotation?
What's this for? And why do these operators affect the final rotation? When I turn off those operators rotation of particles slightly changes.   But these operators don't modify the rotation at all...