Creating Planar Curves

This is done using the Planar page of the New Curve dialog. For additional information see Create New Curve Dialog.

Figure 3:73. Dialog page for creating planar curves

The plane that the new curve lies in is defined by selecting an orientation and a position. In the case of an orthogonal curve (Section, Waterline or Buttock), just a position is required, since the orientation is fixed. The orientation is specified by selecting which coordinate axis is has a constant value - the X-Plane, Y-Plane and Z-Plane Radio buttons correspond to Sections, Buttocks and Waterlines respectively. The value of the constant coordinate is entered in the box to the right of the Radio button. This can consist of a single value, or, in the case of Sections, Waterlines or Buttocks, it can consist of a sequence or range of values. A sequence of curves is given by space separated values, for example 1 1.5 2 3 5 10. A range of values is given using the syntax From(Increment)To. For example 0(2)10 will create (or refit) waterlines 0 through to 10 in increments of 2

There are then three choices for creating the data points that define the curve:

• Freehand - Upon clicking OK, interactive curve creation mode is entered. The user interactively digitizes a sequence of data points in a graphics view with clicks of the Left Mouse button (the view orientation must be parallel to the plane the curve lies in). A double-click of the Left Mouse button inserts the final point and exits interactive curve creation mode. The mode can also be exited by clicking <Esc>. At least two data points are required to define a new curve.

• Interpolation - The data points are formed by intersecting the plane with other curves that already exist. The checkboxes are used to control which types of orthogonal curves are used to form these intersection points. Other curve types (Plines, Tangents, Knuckles ) are always used.

• Import file - select a file, which already contains the data points and select Open. The data points will define a new curve or overwrite an existing curve.

If there is more than one way that the curve could be created, the user is presented with an Options dialog.

Figure 3:74. Options when creating a planar curve

The options are as follows:

• (Re)create by interpolation/import file/free-hand causes the curve’s geometry to be updated according to the chosen operation. This is usually what is intended.

• Activate and use is an option when a curve with the same name already exists, but is inactive. If this option is chosen, this curve is simply activated (no geometry changes occur).

• Copy from existing is an option when an orthogonal curve already exists at the specified position. Choosing this option copies this curve to the new curve, without changing any geometry.

If Cancel is clicked, the curve creation is aborted.