Controlling the curve continuity

When editing interpolation points with the Curve Interpolation Points command, you can set the continuity conditions of the selected curve at its common point with another curve.

Proceed as follows:

1	Click on More Options and select the type of continuity you want to apply from the Snap drop-down list: Positional — positional continuity: the two points coincide and no condition is applied to the tangent vectors of the two curves in the common point. Tangent — tangency continuity: the two points coincide and the tangent vectors of the two curves in the common point lie on the same direction. Perpendicular — perpendicularity continuity: the two points coincide and the tangent vectors of the two curves in the common point are perpendicular.
2	Drag the end point of the spline curve and snap it to the other curve you want to apply the continuity conditions to. The continuity type you specified will be applied.   Positional Tangent Perpendicular
3	Double-click to confirm the changes you made.