It seems that after the vellum solver I used a clean node before the sweep, if I put it after the sweep it fixes the Issue. The clean node probably messed up the orient or rotation, so the sweep couldn't work properly.

added the hip

Hey Guys, so I have build this beginner animation of vellum hair and it is almost there. But these hairs are spinning/rotating and I dont know how to resolve this, maybe someone can help. I just cant find any parameters for rotation. Maybe some vex can fix it? Untitled.mp4 Edit: add hip seaweed4.hiplc