ChangeDegree

Changes the degree of a curve or surface.

Steps:

1. Select the objects.

2. Type a degree value.

   For surfaces type values in the u- and v-directions.

Option

Deformable

If Yes, and the degree of the curve/surface is different from the requested degree, the new curve/surface has simple interior knots.

If No, and the degree of the curve/surface is LESS than the requested degree, the new curve/surface will have exactly the same geometry and parameterization as the original, but it will have knots of multiplicity = old multiplicity + new degree - old degree.

If the degree of the curve/surface is GREATER than the requested degree, then the new curve/surface will be an approximation of the original with simple knots.

Notes

• The ChangeDegree command changes the degree of the polynomial Rhino uses to create the curve. It keeps the knot structure of the curves the same, but it adds or subtracts control points between each knot span.

• Often it is better to use InsertKnot and RemoveKnot instead of ChangeDegree, because you can add/remove control points more locally.

• If you want the surface to have the same geometry, but more control points for editing, then try increasing the degree to 5 with the Deformable option set to No. In this case, you may want to consider using the InsertKnot command, which will add control points but leave the degree unchanged.

• If you are going to export your geometry to another application, make every attempt to keep the degree of your surfaces low. In particular, many mechanical CAD systems cannot import surfaces that have degrees greater than 3.

• The number of control points you add or subtract depends on the degree; the higher the degree, the greater the number of control points.

• If you raise the degree of a surface, it will no longer be periodic. Use MakePeriodic to restore the periodicity of the surface.

• Objects with higher degrees take longer to display and use more memory.

InsertKnot

Inserts knots in curves or surfaces.

Steps:

1. Select the object.

2. Pick a location point for the knot.

   Note: Inserting a knot in a surface also displays an isoparametric curve at the knot location if isoparametric curves are being displayed.

Options

Automatic

Adds a knot/knotline halfway between existing knots to maintain as uniform a structure as possible.

Increases the knot density of a curve or surface to add more control points while maintaining an even knot distribution for better point pulling behavior.

Symmetrical

If Yes, knots are added on both sides of the center of the curve or surface.

Direction

Specify the u-direction, the v-direction, or both.

Toggle

Toggles the direction between u and v.

RemoveKnot

Deletes knots from a curve or surface.

See Also: RemoveMultiKnotSrf

Steps:

1. Select a curve or surface.

2. Click the knot to remove and press Enter.

   Note: Remove knot can be used to remove the connecting joint between two joined curves. The resulting curve will not Explode into separate parts.

Option

Direction

Specify the u-direction, the v-direction, or both.

InsertControlPoint

Adds control points in a curve or a row of control points on a surface.

Steps:

1. Select a curve or surface.

2. Pick a location for the control point or control point row.

   Note: Inserting control points affects the shape of the curve or surface. The InsertKnot command does not change the curve or surface shape.

Options

Direction (U V)

Changes the direction of the control points.

Toggle

Toggles the direction of the control points.

Extend

Extends the surface by half the distance from the end of the surface to the next control points.

Midpoint

Places the control point mid way between two control points.

RemoveControlPoint

Removes control points from a curve or a row of control points from a surface.

Steps:

1. Select a curve or surface.

2. Move the cursor to a point where until control points highlight and click.

   Note: Removing control points affects the shape of the curve or surface.

InsertEditPoint

Adds edit points to a curve.

Steps:

1. Select a curve.

   The edit points are displayed on the selected curve.

2. Pick a location point on the curve.

InsertKink

Adds kinks in a curve.

Steps:

1. Select the curve.

2. Pick locations where you want to insert a kink.

3. Press Enter to end the command.

   The curve is split into multiple joined curves.

MoveUVN

Moves selected surface control points along the surface u-, v-, and normal directions.

Options

U/V/N

Moves a control point in the u-, v-, or normal direction.

Scale

Sets the scale of the sliders in Rhino units.

UV Move mode

Along tangent

The u- and v-sliders move the points in a plane that is roughly tangent to the surface.

Along control polygon

The u- and v-sliders move the points along control polygon chords.

U Symmetry/V Symmetry

Makes it possible to edit two sides of a symmetrical surface at the same time. You must select all points to edit.

Smoothing

Use smoothing before MoveUVN to make it possible to combine the actions. Smoothing tends to even out the control point grid, and the other controls can be used for making small changes to the shape.

MakePeriodic

Makes a non-periodic curve or surface periodic.

Steps:

• Select the objects.

• This command changes a non-periodic surface or curve into a periodic surface or curve. Periodic surfaces and curves deform smoothly without kinks.

Notes

• If a joined curve is made periodic, it becomes a single-span curve and can no longer explode.

• Use the Properties command, Details page to check whether or not a curve is closed and periodic.

MakeNonPeriodic

Makes a periodic curve or surface non-periodic.

Steps:

• Select the objects.

• The MakeNonPeriodic command changes a periodic surface or curve into a non-periodic surface or curve. Non-periodic surfaces and curves can develop kinks when deformed.

Weight

Edits the weight of a curve or surface control point.

The weight of a control point determines how much the curve or surface is attracted to the control point. The higher the value of the weight, the closer the curve or surface is to the control point.

Warning:

If you are exporting to another application, it is best to leave all control point weights at 1.

Steps:

• Use the slider to adjust the weight of the selected control points.

Examples

Weight=1

Weight=0.5

Weight=10