Spline and Polyline. 2D Constructs

The command can be called in one of the following ways:

Splines are drawn basing on a set of points. If the location of points is changed, the spline shape changes too.

Upon calling the command you have to select a type of spline to be created. Type selection is performed via the buttons in the Spline Parameters tab of the parameters window or via the hotkey combinations mentioned below. There are following types available:

The spline goes through given control points.

A polygonal line goes through control points, and the spline is based on such line.

A closed spline goes through given control points.

A closed spline based on polygonal line, where latter goes through control points.

A first degree spline.

A closed first degree spline.

While creating and editing a spline, you can change its type at any moment.

 

The spline drawing command functional in construction lines and in a sketch is practically identical. But there are some minor differences.

•Object snapping doesn't recognize control points of the construction spline.

•A node can be snapped to construction spline, with specifying a relative position along the spline.

•The parameters dialog of a construction spline parameters is different from the one of a sketch spline.

Creating a Spline

Choose one of the aforementioned spline types. Specify the location of control points with . The points can be bound to 2D nodes. The location of the points can be defined using object snapping. Upon specifying a first control point, the dynamic preview of the spline appears on the screen. The last point of the spline follows the cursor, so the preview changes accordingly. When creating a spline by polyline, a preview of a polyline is shown along with a preview of a spline.

 

Coordinates and other parameters of the specified points, as well as geometrical parameters of the spline as whole, are shown in the parameters window (see the Geometrical Parameters of Spline section).

Specify control points, their parameters, parameters of spline as whole and then finish the spline creation using either the (<Ctrl>+<Enter>) option, or double click .

Spline Drawing

Spline command now supports a continuous curve input holding the left mouse button pressed, i.e. implemented is the feature of spline painting.

 

In this case, the spline points are added automatically. Spline generation accuracy is set in the system options (Options > Snap > Snap > Spline approximation accuracy (px)). Accuracy is measured in pixels, i.e. it depends on the current image scale in the working window.

Automenu options

Following options are available upon calling the command:

This option invokes the spline's parameters dialog

This option allows you to construct a spline symmetrical to the existing one. After activating the option, select a straight construction line and then the existing spline. The resulting spline keeps the associative link with the initial one: all the changes in the initial spline affect the symmetrical one.

 

This option allows you to construct a spiral line based on three points. Upon activating this option, you have to specify three points. First point is the center of the spiral, second point defines the starting radius, third point defines the ending radius. After specifying first and second point, additional option appears in the automenu, allowing you to reverse the spiral direction:

Upon activating this option, select a graphic line. In result a spline will be instantly created. Shape of the created spline fully coincides with the shape of the selected graphic line.

 

To finish spline creation, use the following option:

Upon finishing the input, the system starts creation of another spline.

To cancel a spline creation, use the following option or the :

Whenever two or more control points are defined, the right-click , as well as the option, brings up the Right button action dialog, unless the Don't Show this dialog in future option was enabled earlier in the current session. Upon selecting the Continue operation action in the dialog, adding control points to the end of the spline stops, but you can still can add intermediate ones by clicking at the desired location on the spline or edit any of the spline's parameters. In order to resume adding points to the end of the spline, select the last point in the list of points displayed in the parameters window and click the Add after button.

Topics in this section:

•Spline Analysis

•Main Concepts of 2D Spline

•2D Spline Point Controls

•Geometrical Parameters of 2D Spline

•General Parameters of 2D Construction Spline

See also:

•Edit Splines

•Right button action

•Spline based on 3D Nodes