geom/doc/salome/gui/GEOM/input/creating_curve.doc

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\page create_curve_page Curve

To create a \b Curve in the <b>Main Menu</b> select <b>New Entity - >
Basic - > Curve</b>

There are three <b>Curve Construction</b> menu choices corresponding to three
possible types of curves: Polyline, Besier or B-spline (Interpolated).
The curve is defined by a list of \b Points through which it passes.


\n There are two ways to define these <b>Points</b>:
<ul>
<li> <b>By Selection</b> manual picking of the points in the Object Browser or 3D Viewer.
<li> <b>Analytical</b> parametric definition of the points through
python expressions.
</ul>

\n The \b Result of each operation will be a GEOM_Object (edge).

<b>Polyline</b>

\image html polyline.png

Polyline or polygonal chain is a connected series of line segments. It
can be defined by the following parameters:

\image html curve2.png

<ul>
<li><b>Points</b> at least 2 points which will serve as nodes on the curve.</li>
<li><b>Build a closed wire</b> checkbox allows creating the curve as
closed wire.</li>
</ul>

\n <b>TUI Command:</b> <em>geompy.MakePolyline(ListOfShapes,isClosed)</em>

<b>Bezier</b>

\image html bezier.png

Bezier curve is a curve completely contained in a convex hull of its
control points. It can be defined by the following parameters:


\image html curve3.png

<ul>
<li><b>Points</b> at least 2 points used to approximate the curve.</li>
<li><b>Build a closed edge</b> checkbox allows creating the curve as
closed edge.</li>
</ul>

\n <b>TUI Command:</b> <em>geompy.MakeBezier(ListOfShapes,isClosed)</em>

<b>B-spline</b>

\image html interpol.png

B-spline is a union of curve segments defined at each node span. It
can be defined by the following parameters:

\image html curve4.png

<ul>
<li><b>Points</b> at least 2 points which will serve as nodes on the curve.</li>
<li><b>Build a closed edge</b> checkbox allows creating the curve as
closed edge.</li>
<li> If <b>Reorder vertices taking into account distances</b> is
checked, the interpolation algorithm does not follow the order of
vertices but searches for the closest vertex.</li>
<li><b>Tangents</b> are two vectors, defining direction of curve at
its ends. Both or none vectors must be set. This option available only
if two above check boxes are not checked.
</li>
</ul>

\n <b>TUI Command:</b>
<br><em>geompy.MakeInterpol(ListOfShapes,isClosed,doReordering)</em>
<br><em>geompy.MakeInterpolWithTangents(ListOfShapes,Vector1,Vector2)</em>

<b>Analytical Definition</b>

The input parameters for analytical definition are common for all
types of curves. 

\image html curve1.png

<ul>
<li><b>X(t)equation, Y(t)equation, Z(t)equation</b> are python
expressions for X, Y and Z coordinates of the basic points of the curve.</li>
<li><b>Min t, Max t</b> are minimum and maximum values of the parameter \b t.</li>
<li><b>Step</b> is the number of steps of the parameter \b t.</li>
</ul> 

\n <b>TUI Command:</b> <em>geompy.MakeCurveParametric(XExpr, YExpt, ZExpt, tMin, tMax, nbSteps, curveType, True)</em>

\n<b>Advanced options</b> \ref preview_anchor "Preview"

Our <b>TUI Scripts</b> provide you with useful examples of creation of 
\ref tui_creation_curve "Basic Geometric Objects".

*/