Reverses the parametric (U) direction of a curve, causing the start of the curve to become the end, and vice-versa.
This tool also lets you examine the tangent direction on the curve.
To reverse the direction of a curve
.
The tangent of the curve is shown at the point where you clicked.
and drag along the curve to examine the tangent direction.
or the Reverse Active button in the window to reverse the curve you clicked.
or the Reverse All button in the window to reverse all selected curves.