Boundary Curve

InsertCurveBoundaries

The Boundary Curve command enables you to creates the boundary curves of a surface or a mesh (or face of a solid). You will first have to select the surface/mesh. Then, in the Boundaries drop-down list, you can select the method to be used to create the boundary curves:

All	to create all the boundary curves of the surfaces you will select
Select	To create only the curves corresponding to the boundaries you will select.
Free Boundary	(Applies to solids only) To create the curves corresponding to the free boundaries of the selected faces belonging to the same solid: free boundaries are the ones that are not common to more than one of the selected faces. The resulting curves will be the free boundaries of the selected set of faces.

If the surface is not trimmed, the boundary curves are the isoparametric curves of the surface corresponding to the minimum and maximum values of both sets of surface parameters (u=0, v=0, u=1,and v=1). In other words, the command produces four boundary curves corresponding to the following values for u and v:

u=0 and v variable from 0 to 1
v=0 and u variable from 0 to 1
u=1 and v variable from 0 to 1
v=1 and u variable from 0 to 1

Some boundaries may be degenerate, that is, reduced to a point. For example, the vertex of a cone is the degenerate isoparametric curve you obtain when v=1.

Other boundaries may be superimposed. For example, in the case of a cone or cylinder, the two generators u=0 and u=1 are superimposed. Boundaries that are not superimposed are called real boundaries.

An Insert Curve on Surface check box is available in the selection list, enabling you to create curves of the "Curve on Surface" type (See " Curves on Surfaces" for details).

When Insert Curve on Surface is selected, the resulting curves will be of the Curve on Surface type.
When Insert Curve on Surface is cleared, the curve type depends on the command and on the situation (generally a NURBS). In this case, an additional option is available under More Options: High quality approximation.
- When the check box is selected, the resulting curves will be G3 or G4 continuous and will have higher degree.
- When the check box is cleared, the resulting curves will have degree 3 and continuity 2.

The Associative Mode check box is also available, enabling you to create curves which retain a link to the surface they derive from. See further details on associativity for curves of the Curve on Surface type in " Curves on Surface".

If you interrupt the command, your selections and settings are not lost: they are "frozen" in order to enable you to use them again without having to repeat them all.
Next time you start the command, in fact, the Restore Selection button ( ) will be displayed on top of the selection list. If you select the Restore Selection button ( ), all the selections you made and the settings you defined last time you used the command will be restored, enabling you to go on with no need to repeat those selections/settings.
When the command is started with some pre-selected entities, if you click the Restore Selection button you will be asked to confirm restoring the frozen command selections, thus resetting the current selection.

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