I have a nurb/b-spline curve in 2d, and I want to sweep a cross section along it.
Here is the curve and resulting "tube" (green points are control points):
However, as you can see, the resulting "tube" becomes thinner where the curve curves. So my question is, what is the correct way of sweeping a cross section along a bspline curve and obtaining constant height of the cross section?
My current method is to pick some points along the curve (Greville points) (in the parametric coordinate system), and rotating the cross section such that it aligns with the normal of the curve at the current point...but it does not seems to work.