利用者:Jaredr122/Doc:2.6/Manual/Modeling/Curves/Editing

Curve Editing

This page covers the basics of curve editing – more advanced topics, like extrusion (and bevel and taper), are addressed in the next sections:Curve Deform and Extruding

Creating Curves

Blender has five different curve primitives, two Bézier and three NURBS:

Bezier Curve

adds an open 2D Bézier curve with two control points.

Bezier Circle

adds a closed, circle-shaped 2D Bézier curve (made of four control points).

NURBS Curve

adds an open 2D NURBS curve, with four control points, with Uniform knots.

NURBS Circle

adds a closed, circle-shaped 2D NURBS curve (made of height control points).

Path

adds a NURBS open 3D curve made of five aligned control points, and with Endpoint knots and the CurvePath setting enabled.

Curve Display

Display Options

When in edit mode, the properties window contains options under Curve Display for how curves are displayed in the 3d viewport.

Handles

Toggles the display of Bezier handles while in edit moe. This does not affect the appearance of the curve itself. See Curves for more about handle types.

Normals

Toggles the display of Curve Normals.

Normal Size

Sets the display scale of curve normals. Not that this is relative to the control point scale which can be explicitly set, and is reflected in the normals as well.

Hiding Elements

As in Object mode, you can hide what is selected, and then reveal what was hidden. This is very handy to clean up a bit your views, when you are working on a complex model with thousands of vertices…

To hide, use CtrlAltH, the Hide button of the Curve Tools1 panel, or use the Curve » Show/Hide Control Points » Hide Selected menu option.

To reveal what was hidden, use AltH, the Reveal button of the Curve Tools1 panel, or the relevant option in the same Curve » Show/Hide Control Points menu.

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Basic Curve Editing (translation, rotation, scale)

Mode: Edit mode

Hotkey: G/R/S

Menu: Curve » Transform » Grab/Move, Rotate, Scale, …

Once you have a selection of one or more control points, you can grab/move (G), rotate (R) or scale (S) them, like many other things in Blender, as described in the Manipulation in 3D Space section.

Note that Bézier control points contain three vertices (the central one and the two handles), so a whole selected control point is equivalent to three selected vertices for transform tools (i.e. you can rotate and scale it, unlike standard mesh or NURBS vertices).

Note that in general, Bézier curves are easier to edit than NURBS, as when you modify a control point, you only affect the two curve segments on both side of the point. With NURBS, when you move a vertex, the curve can be modified up to three point on both side, depending on the order of the curve… Moreover, a Bézier curve always pass through the center of all its control points – NURBS are far from being so simple!

You also have in Edit mode an extra option when using these basic manipulations: the proportional editing.

Snapping

Mode: Edit mode

Panel: Curve Tools1 (Editing context)

Mesh snapping also works with curve components.

Both control points and their handles will be affected by snapping, except for within itself (other components of the active curve).

Snapping works with 2D curves, however points will be constrained to the curve's local XY axis.

Deforming Tools

Mode: Edit mode

Menu: Curve » Transform

The To Sphere, Shear, Wrap and Push/Pull transform tools are described in the Manipulation in 3D chapter.

The two other tools, Tilt and Shrink/Fatten Radius are related to Curve Extrusion.

Smoothing

Mode: Edit mode

Hotkey: W » smooth

Curve smoothing is available through the specials menu. For Bezier curves, this smoothing operation currently only smooths the positions of control points and not their tangents. End points are also constrained when smoothing.

Mirror

Mode: Edit mode

Hotkey: CtrlM

Menu: Curve » Mirror

The Mirror tool is also available, behaving exactly as with mesh vertices,

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Set Bézier Handle Type

Mode: Edit mode

Panel: Curve Tools » Handles

Hotkey: V

Menu: Curve » Control Points » Set Handle Type

This only concerns Bézier curves. As we saw in a previous page, these curves can have four types of handles (giving smooth or angled curve…). ⇧ ShiftH makes all selected control points automatic, H toggles between free and aligned, and V makes them vector. Follow above link for more details.

Extending Curves

Mode: Edit mode

Hotkey: CtrlLMB or E

Menu: Curve » Extrude

Once a curve is created you can add new segments (in fact, new control points defining new segments…), either by extruding it, or placing new handles with CtrlLMB clicks. Each new segment is added to one end of the curve. A new segment will only be added if a single vertex, or handle, at one end of the curve is selected. If two or more control points are selected nothing is added (however, if you used the E Extrude command, all selected control points are placed in Grab mode…).

Note that unlike with meshes, you can’t create a new curve inside the edited object by just CtrlLMB -clicking with nothing selected – to do so, you can cut an existing curve in two parts (by deleting a segment), copy an existing one (⇧ ShiftD), or add a new one (Add menu)…

Subdivision

Mode: Edit mode

Panel: Curve Tools (Editing context)

Hotkey: W » 1

Menu: Curve » Segments » Subdivide

Curve subdivision simply subdivides all selected segments by adding one or more control points between the selected segments.

Number of Cuts

Subdivides the segment multiple times evenly spacing this number of control points.

Duplication

Mode: Edit mode

Hotkey: ⇧ ShiftD

Menu: Curve » Duplicate

This command duplicates the selected control points, along with the curve segments implicitly selected (if any). The copy is selected and placed in Grab mode, so you can move it to another place.

Joining Curve Segments

Mode: Edit mode

Hotkey: F

Menu: Curve » Make Segment

Two open curves can be combined into one by creating a segment between the two curves. To join two separated use one end control point from each curve. The two curves are joined by a segment to become a single curve.

Two curves.

One curve joined.

Additionally, you can close a curve by joining the endpoints

Note that you can only join curves of the same type (i.e. Bézier with Bézier, NURBS with NURBS)

Separating Curves

Mode: Edit mode

Hotkey: P

Menu: Curve » Separate

Curve object that are made of multiple distinct splines can be separated into their own objects. Note, if there is only one spline in a curve object, separating when something is selected will create a new curve object with no control points.

Deleting Elements

Mode: Edit mode

Hotkey: X or Del

Menu: Curve » Delete...

The Erase pop-up menu of curves offers you three options:

Selected

This will delete the selected control points, without breaking the curve (i.e. the adjacent points will be directly linked, joined, once the intermediary ones are deleted). Remember that NURBS order cannot be higher than its number of control points, so it might decrease when you delete some control points… Of course, when only one point remains, there is no more visible curve, and when all points are deleted, the curve itself is deleted.

Segment

This option is somewhat the opposite to the preceding one, as it will cut the curve, without removing any control point, by erasing one selected segment.

This option always removes only one segment (the last “selected” one), even when several are in the selection. So to delete all segments in your selection, you’ll have to repetitively use the same erase option…

All

As with meshes, this deletes everything in the object!

Opening and Closing a Curve

Mode: Edit mode

Hotkey: AltC

Menu: Curve » Toggle Cyclic

This toggles between an open curve and closed curve (Cyclic). Only curves with at least one selected control point will be closed/open.

The shape of the closing segment is based on the start and end handles for Bézier curves, and as usual on adjacent control points for NURBS. The only time a handle is adjusted after closing is if the handle is an Auto one. (Open curve) and (Closed curve) is the same Bézier curve open and closed.

This action only works on the original starting control-point or the last control-point added. Deleting a segment(s) dosen’t change how the action applies; it still operates only on the starting and last control-points. This means that AltC may actually join two curves instead of closing a single curve!

Remember that when a 2D curve is closed, it creates a renderable flat face.

Open curve.

Closed curve.

Closed curve (Solid).

Switch Direction

Mode: Edit mode

Hotkey: W » 2 NumPad

Menu: Curve » Segments » Switch Direction, Specials » Switch Direction

This command will “reverse” the direction of any curve with at least one selected element (i.e. start point will begin end one, and vice-versa). Mainly useful when using curve as path, or the bevel and taper options…

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Converting Tools

Converting Curve Type

Mode: Edit mode

Panel: Curve Tools1

You can convert splines in a curve object between Bézier, NURBS, any Poly curves.

The Set Spline type button of the Curve group, in the Curve Tools panel, allow you to convert selected splines to the chosen type. Note this is not a “smart” conversion, i.e. Blender do not tries to keep the same shape, nor the same number of control points… For example, when converting a NURBS to a Bézier, each group of three NURBS control points become a unique Bézier one (center point and two handles).

Convert Curve to Mesh

Mode: Object mode

Menu: Object » Convert to

There is also an “external” conversion, from curve to mesh, that only works in Object mode. It transforms a Curve object in a Mesh one, using the curve resolution to create edges and vertices. Note also it keeps the faces and volumes created by closed and extruded curves…

Convert Mesh to Curve

Mode: Object mode

Menu: Object » Convert to

Mesh objects that consist of a series of connected vertices can be converted into curve objects. The resulting curve will be a Poly curve type, but can be converted to have smooth segments as described above.

Curve Parenting

Mode: Edit mode

Hotkey: CtrlP

You can make other selected objects children of one or three control points (CtrlP, as with mesh objects.

Select either 1 or 3 control points, then CtrlRMB another object and use CtrlP to make a vertex parent.

Hooks

Mode: Edit mode

Hotkey: H

Menu: curve » control points » hooks

Hooks can be added to control one or more points with other objects.

Set Goal Weight

Mode: Edit mode

Menu: W » Set Goal Weight

Set Goal Weight

This sets the “goal weight” of selected control points, which is used when a curve has Soft Body physics, forcing the curve to "stick" to their original positions, based on the weight.