RailwayRouteOptimization/scripts/Draw/Spline/SplineControlPoints/doc/SplineControlPoints_en.html

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<title>Spline (Control Points)</title>
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<p style="text-align:right;"><a href="/doc/qcad/latest/reference/en/index.php?page=scripts/Draw/Spline/SplineControlPoints/doc/SplineControlPoints">&#160;&#160;&#160;&#160;&#160;&#160;</a></p>
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<h2>Spline (Control Points)</h2>
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<b>Toolbar / Icon:</b>
<br /><img src="../../doc/Spline.png" width="40" height="40" />
&#160;&#160;&#160;
<img src="../doc/SplineControlPoints.png" width="40" height="40" />
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<b>Menu:</b> <font face="courier new">Draw &gt; Spline &gt; Spline (Control Points)</font>
<br /><b>Shortcut:</b> <font face="courier new">S, P</font>
<br /><b>Commands:</b> <font face="courier new">spline | sp</font>
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<h3>Description</h3>
<p>Draws spline curves from control points. Non-uniform rational B-Splines
(NURBS) with homogeneous weighting factors are the only splines that are
supported.</p>
<h3>Usage</h3>
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  <ol>
    <li>Choose the degree of the spline in the options tool bar. Supported
    degrees are 2 (quadratic b-spline) and 3 (cubic b-spline). The higher the
    degree, the 'smoother' the curve becomes. 
    <br />Note that a quadratic b-spline requires by definition at least 3
    control points while a cubic b-spline has at least 4 control points.</li>
    <li>Check the 'Closed' check box in the options tool bar if you want to
    create a closed spline. Closed splines are continuous closed loops.</li>
    <li>Specify the control points. After defining the third (for quadratic
    b-splines) or fourth (for cubic b-splines) control point, a preview will be
    shown. You can remove the last control point again by clicking the 'Undo'
    button in the options tool bar.</li>
    <li>Hit escape or click the right mouse button after setting the last point
    to confirm the spline shape.</li>
    <li>You can now create another spline or right-click again to terminate the
    tool.</li>
  </ol>
  <p>Example for two open splines (quadratic and cubic): 
  <br />
  <img src="SplineControlPoints01.png" class="figure" />
  <br />Example for two closed, periodic splines (quadratic and cubic): 
  <br />
  <img src="SplineControlPoints02.png" class="figure" /></p>
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