One guide curve and several section curves:

Menu access: Shape | Other shapes | Swept

Description:

One guide curve and several section curves option is defined as a surface swept by several curves named "mixed section curves" moving along another curve named "guide curve".

Principle:

The mixed section curve is obtained by mixing the curves named section curves, which can be closed or open, not necessarily planar and can have angular points.

Each section curve has got a hooking point on the guide curve corresponding to the point where the mixed section curve is strictly equal to the section curve.

Between two hooking points, the mixed section curve is equal to a mix of the two section curves following an evolution law which can be linear or not.

The resulting swept surface must not have auto-intersection area.

General philosophy:

1. Choose the method of sweeping: Normal, Vertical, Translated or On faces (cf. method of sweeping).

2. Select the guide curve and choose its direction.

3. Select the vertical direction (if asked according to the sweeping method chosen).

4. Select the section curves, select their directions and hooking points or select on the  POSITION SECTION CURVE  button (cf. positioning).

Optional point(s):

The  AUTOMATIC  button allows to automatically select all the curves that intersect the guide curve in order to use them as section curves.

 Positioning:

The section curve is usually defined "in place"; id est. its position is the one corresponding to the initial sweeping coordinate system.

Nevertheless, it is also possible to choose the section curve in another coordinate system by pressing the  POSITION SECTION CURVE  button. In that case, the section curve will automatically be positioned in the initial sweeping coordinate system before starting the sweeping.

 Method of sweeping:

In order to define exactly the sweeping movement, the easiest is to consider the section curve fixed in coordinate system which origin moves along the guide curve. This coordinate system is called "sweeping coordinate system".

There are different ways to define the sweeping coordinate system, allowing getting several kind of geometry.

The following drop down list allows you to choose the sweeping mode: .

To understand the principles of each sweeping mode, we need to give a precise description of the sweeping coordinate system. Its origin moving along the guide curve, you just have to precise its orientation

For this, we will use the following conventions:

• The V vector represents the vertical direction.

• The T vector is the tangent of the guide curve on the origin of the sweeping coordinate system.

• X, Y and Z are the vectors defining the orientation of the sweeping coordinate system.

Comparison of these modes. 

 Intermediate sections generation:

 MAKE SECTION

The swept shape calculation is made using two steps: intermediate sections calculation, then creation of the template shape on these sections.

It is possible to generate intermediate sections when creating a swept or later with the "Modify" function.

This functionality is very useful in two cases:

• The swept failed, usually due to an auto-intersection area: the generation of the sections allows you to visualize the problem spot.

• The swept doesn't give the expected result: it is advisable to generate intermediate sections, modify the unsatisfactory ones and create a loft shape.

The list allows you to choose the correspondence between the curves

The option  Curves= VISIBLE  or  HIDDEN  allows you to keep visible or not the curves after the ruled shape is created.

When curves are closed, you can choose the type of shape to create with the option  Type= SOLID  or  SURFACE TYPE . When you choose the solid type, the created shape will be solid if possible. If not, not any message will appear.

 The option allows you to choose the type of synchronization between the curves.

The list allows you to choose the mixing of the section curves.

In the SMOOTH modes, if the guide curve is closed, you need at least 4 section curves.

Specific point(s):

 The guide curve can be open or closed, not necessarily planar, but it must be tangentially continuous (no angular point).

 The section curves can be open or closed, not necessarily planar and can have angular points.

 If the guide curve is closed, you must select a minimum of 4 section curves.

 For closed curves, the origin has a great influence on the result. It can be visualized and modified with the function Curve | Origin

If the origins are not aligned enough, the shape may be too much "twisted" and cannot be generated.