Change the way a constraint affects the direction of the curve as it passes through the constraint.
Change the type of the picked blend points
Choose Curves > Blend curv toolbox to show an extra floating palette containing the BlendCrv Tools tab.
Do one of the following:
> Blend Constraint
Interp Location.
> Blend Constraint
Interp direction.
> Blend Constraint
Interp Geometry.
Change the type of a directional constraint
Do one of the following:
> Blend constraint
directed.
> Blend constraint
parallel.
See also Blend curves.