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<title>Ipe Manual -- 5.5 Examples</title>
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.maketitle { text-align : center }
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<table width="100%" cellpadding=0 cellspacing=2><tr>
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<td bgcolor="#99ccff"><img alt="" src="blank.png"></td><td bgcolor="#99ccff"><a href="manual_21.html"><img border="0" alt="5 Snapping" src="up.png"></a></td><td bgcolor="#99ccff"><a href="manual_25.html"><img border="0" alt="5.4 Interaction of the snapping modes" src="previous.png"></a></td><td align="center" bgcolor="#99ccff" width="100%"><b>5.5 Examples</b></td></tr></table>
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<p>It takes some time and practice to feel fully at ease with the different
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snapping modes, especially angular snapping. Here are some examples
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showing what can be done with angular snapping.
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<h4><a name="id1">Example 1:</a></h4>
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We are given segments <i>s<sub>1</sub></i>, <i>s<sub>2</sub></i>, and <i>e</i>, and we want
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to add the dashed vertical extensions through <i>p</i> and <i>q</i>.
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<div align="center"><p>
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<object type="image/svg+xml" data="example1.svg"
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name="example1"></object>
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<ul class="menu"><li>set <kbd>F4</kbd> and <kbd>F5</kbd> snapping on, go into <em>line</em> mode, and
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reset axis system with <kbd>Shift-F2</kbd>,
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<li>go near <i>p</i>, press <kbd>F1</kbd> and <kbd>F8</kbd> to set origin and
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to turn on angular snap.
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<li>go near <i>p'</i>, click left, and extend segment to <i>s<sub>2</sub></i>.
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<li>go near <i>q</i>, press <kbd>F1</kbd> to reset origin, and draw second
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extension in the same way.
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<h4><a name="id2">Example 2:</a></h4>
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We are given the polygon <i>C</i>, and we want to draw the bracket
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<i>b</i>, indicating its vertical extension.
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<div align="center"><p>
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<object type="image/svg+xml" data="example2.svg"
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name="example2"></object>
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<ul class="menu"><li>set <kbd>F4</kbd> and <kbd>F9</kbd> snapping on, go into <em>line</em> mode, reset
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axis system, set snap angle to
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<li>go near <i>p</i>, press <kbd>F1</kbd> and <kbd>F8</kbd> to set origin and
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<li>go to <i>x</i>, click left, extend segment to <i>y</i>, click left
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<li>now we want to have <i>z</i> on a horizontal line through <i>q</i>:
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go near <i>q</i>, and press <kbd>F1</kbd> and <kbd>F8</kbd> to reset origin
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and to turn on angular snapping. Now both angular snapping modes are
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on, the snap lines intersect in <i>z</i>.
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<li>click left at <i>z</i>, goto <i>x</i> and press <kbd>F1</kbd>, goto
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<i>t</i> and finish bracket.
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<h4><a name="id3">Example 3:</a></h4>
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We want to draw the following "skyline". The only problem is to get
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<i>q</i> horizontally aligned with <i>p</i>.
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<div align="center"><p>
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<object type="image/svg+xml" data="example3.svg"
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name="example3"></object>
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<ul class="menu"><li>draw the baseline using automatic angular snapping to get it
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<li>place <i>p</i> with boundary snapping, draw the rectilinear curve up to
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<i>r</i> with automatic angular snapping in
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<li>now go to <i>p</i> and press <kbd>F1</kbd> and <kbd>F8</kbd>. The snap lines
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intersect in <i>q</i>. Click there, turn off angular snapping with
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<kbd>Shift-F2</kbd>, and finish curve. The last point is placed with
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<h4><a name="id4">Example 4:</a></h4>
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We want to draw a line through <i>p</i>, tangent to <i>C</i> in
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<div align="center"><p>
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<object type="image/svg+xml" data="example4.svg"
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name="example4"></object>
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<ul class="menu"><li>with vertex snapping on, put origin at <i>p</i> with <kbd>F1</kbd>
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<li>go to <i>q</i> and press <kbd>F2</kbd>. This puts the base direction from
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<i>p</i> to <i>q</i>.
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<li>set angular snapping with <kbd>F8</kbd> and draw line.
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<h4><a name="id5">Example 5:</a></h4>
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We want to draw the following "windmill". The angle of the sector and
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between sectors should be
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<div align="center"><p>
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<object type="image/svg+xml" data="example5.svg"
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name="example5"></object>
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<ul class="menu"><li>set vertex snapping, snap angle to
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reset axis system with <kbd>Shift-F1</kbd>,
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<li>with automatic angular snapping, draw a horizontal segment <i>pq</i>.
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<li>go to <i>p</i>, place origin and turn on angular snapping with
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<kbd>F1</kbd> and <kbd>F8</kbd>,
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<li>duplicate segment with <kbd>d</kbd>, go to <i>q</i> and pick up <i>q</i> for
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rotation (with <font color="#0000ff">Ctrl</font> and the middle mouse button). Rotate until
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segment falls on the next snap line.
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<li>turn off angular snapping with <kbd>F8</kbd>. Choose arc mode, variant
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"center & two points".
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<li>go to <i>p</i>, click for center. Go to <i>q</i>, click for first
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endpoint of arc, and at <i>r</i> for the second endpoint. Select all,
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<li>turn angular snapping on again. Duplicate sector, and rotate by
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using angular snapping.
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<li>duplicate and rotate four more times.
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<h4><a name="id6">Example 6:</a></h4>
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We want to draw a <i>c</i>-oriented polygon, where the angles between
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successive segments are multiples of
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The automatic angular snapping mode makes this pretty easy, but there is a
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little catch: How do we place the ultimate vertex such that it is at the
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same time properly aligned to the penultimate and to the very first vertex?
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<div align="center"><p>
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<object type="image/svg+xml" data="example6.svg"
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name="example6"></object>
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<ul class="menu"><li>set snap angle to
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and turn on automatic angular snapping.
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<li>click first vertex <i>p</i> and draw the polygon up to the penultimate
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<li>it remains to place <i>r</i> such that it is in a legal position both
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with respect to <i>q</i> and <i>p</i>. The automatic angular snapping
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mode ensures the position with respect to <i>q</i>. We will use
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angular snapping from <i>p</i> to get it right: Go near <i>p</i> and
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turn on vertex snapping. Press <kbd>F1</kbd> to place the origin
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at <i>p</i> and <kbd>F8</kbd> to turn on angular snapping. Now it is
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trivial to place <i>r</i>.
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<table width="100%" cellpadding=0 cellspacing=2><tr>
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<td bgcolor="#99ccff"><img alt="" src="blank.png"></td><td bgcolor="#99ccff"><a href="manual_21.html"><img border="0" alt="5 Snapping" src="up.png"></a></td><td bgcolor="#99ccff"><a href="manual_25.html"><img border="0" alt="5.4 Interaction of the snapping modes" src="previous.png"></a></td><td align="center" bgcolor="#99ccff" width="100%"><b>5.5 Examples</b></td></tr></table></body></html>