To create a curve on surface

1. Click the New Curve-on-surface icon, or choose Curves > New Curve-on-surface from the tool palette.
2. Click the surface on which you will draw the new curve-on-surface.
3. Click to place the points of the new curve. You can move the new point while the mouse button is down. When you release the mouse button, the new point is added to the curve.
   • Click the to place a point.
   • Click the to place a point with the same U coordinate as the previous one.
   • Click the to place a point with the same V coordinate as the previous one.
   • Type a UV coordinate to place a point exactly.
   • Use snapping to snap to the nearest isoparametric curve intersection.
   • Use snapping to snap to the nearest edit point of a curve on surface on that surface.
   • Use snapping to snap to another curve-on-surface, or to an isoparametric curve.
   • If Curve Snap Intersections is turned on in Preferences > General Preferences (Modeling section), snapping will automatically snap a new curve-on-surface (CoS) to CoS-CoS intersections on the same surface.
4. Use + Z or Edit > Undo to remove the last point. Use Edit > Redo to put it back.
   Note

   As with any other operation, the maximum number of undos is set to 11 but can be modified in the Miscellaneous section of Preferences > General Preferences.

New Curve on Surface Options

Curve Degree

The mathematical degree of the curve created, which control the number of CVs per span: 1 (linear) or 3 (cubic). The default is 3.

Knot Spacing

A “knot” is the parameter value of an edit point.

Chord – The chord length parameterizes the new curve edit points in current units.

Uniform – The new curve edit points have integral parameters: the first edit point is parameter 0.0, the second is 1.0, and so on.