Rough or smooth

For the creation of this piece, first I implemented a vector field and put some particles as my objects in it. In code art it is very important to always experiment with different values or functions, see what happens when you switch a thing or two. So I combined some logarithmic and trigonometric functions, and got an interesting vector field, but then I thought, what if I only set a white color for all the particles that have mainly horizontal acceleration. And as we see, this was created. But