~ubuntu-branches/ubuntu/precise/ipe/precise

<table width="100%" cellpadding=0 cellspacing=2><tr><td bgcolor="#99ccff"><img alt="" src="blank.png"></td><td bgcolor="#99ccff"><a href="manual_22.html"><img border="0" alt="6 Snapping" src="up.png"></a></td><td bgcolor="#99ccff"><a href="manual_26.html"><img border="0" alt="6.4 Interaction of the snapping modes" src="previous.png"></a></td><td align="center" bgcolor="#99ccff" width="100%"><b>6.5 Examples</b></td></tr></table>

<h2>6.5 Examples</h2>

<p>It takes some time and practice to feel fully at ease with the different

snapping modes, especially angular snapping. Here are some examples

showing what can be done with angular snapping.

<h4><a name="id1">Example 1:</a></h4>

We are given segments <i>s<sub>1</sub></i>, <i>s<sub>2</sub></i>, and <i>e</i>, and we want

to add the dashed vertical extensions through <i>p</i> and <i>q</i>.

</p></div>

<ul class="menu"><li>set <kbd>F4</kbd> and <kbd>F5</kbd> snapping on, go into <em>line</em> mode, and

reset axis system with <kbd>Shift-F1</kbd>,

<li>go near <i>p</i>, press <kbd>F1</kbd> and <kbd>F8</kbd> to set origin and

to turn on angular snap.

<li>go near <i>p'</i>, click left, and extend segment to <i>s<sub>2</sub></i>.

<li>go near <i>q</i>, press <kbd>F1</kbd> to reset origin, and draw second

extension in the same way.

</ul>

<h4><a name="id2">Example 2:</a></h4>

We are given the polygon <i>C</i>, and we want to draw the bracket

<i>b</i>, indicating its vertical extension.

</p></div>

<ul class="menu"><li>set <kbd>F4</kbd> and <kbd>F9</kbd> snapping on, go into <em>line</em> mode, reset

axis system, set snap angle to

90 degrees.

<li>go near <i>p</i>, press <kbd>F1</kbd> and <kbd>F8</kbd> to set origin and

angular snapping

<li>go to <i>x</i>, click left, extend segment to <i>y</i>, click left

<li>now we want to have <i>z</i> on a horizontal line through <i>q</i>:

go near <i>q</i>, and press <kbd>F1</kbd> and <kbd>F8</kbd> to reset origin

and to turn on angular snapping. Now both angular snapping modes are

on, the snap lines intersect in <i>z</i>.

<li>click left at <i>z</i>, goto <i>x</i> and press <kbd>F1</kbd>, goto

<i>t</i> and finish bracket.

</ul>

<h4><a name="id3">Example 3:</a></h4>

We want to draw the following "skyline". The only problem is to get

<i>q</i> horizontally aligned with <i>p</i>.

</p></div>

<ul class="menu"><li>draw the baseline using automatic angular snapping to get it

horizontal.

<li>place <i>p</i> with boundary snapping, draw the rectilinear curve up to

<i>r</i> with automatic angular snapping in

90 degrees mode.

<li>now go to <i>p</i> and press <kbd>F1</kbd> and <kbd>F8</kbd>. The snap lines

intersect in <i>q</i>. Click there, turn off angular snapping with

<kbd>Shift-F1</kbd>, and finish curve. The last point is placed with

boundary snapping.

</ul>

<h4><a name="id4">Example 4:</a></h4>

We want to draw a line through <i>p</i>, tangent to <i>C</i> in

<i>q</i>.

</p></div>

<ul class="menu"><li>with vertex snapping on, put origin at <i>p</i> with <kbd>F1</kbd>

<li>go to <i>q</i> and press <kbd>F2</kbd>. This puts the base direction from

<i>p</i> to <i>q</i>.

<li>set angular snapping with <kbd>F8</kbd> and draw line.

</ul>

<h4><a name="id5">Example 5:</a></h4>

We want to draw the following "windmill". The angle of the sector and

100

between sectors should be

101

30 degrees.

102

103

104

</p></div>

105

<ul class="menu"><li>set vertex snapping, snap angle to

106

30 degrees,

107

reset axis system with <kbd>Shift-F1</kbd>,

108

<li>with automatic angular snapping, draw a horizontal segment <i>pq</i>.

109

<li>go to <i>p</i>, place origin and turn on angular snapping with

110

<kbd>F1</kbd> and <kbd>F8</kbd>,

111

<li>duplicate segment with <kbd>d</kbd>, go to <i>q</i> and pick up <i>q</i> for

112

rotation (with Ctrl and the middle mouse button). Rotate until

113

segment falls on the next snap line.

114

<li>turn off angular snapping with <kbd>F8</kbd>. Choose arc mode, variant

115

"center & two points".

116

<li>go to <i>p</i>, click for center. Go to <i>q</i>, click for first

117

endpoint of arc, and at <i>r</i> for the second endpoint. Select all,

118

and group.

119

<li>turn angular snapping on again. Duplicate sector, and rotate by

120

60 degrees

121

using angular snapping.

122

<li>duplicate and rotate four more times.

123

</ul>

124

125

<h4><a name="id6">Example 6:</a></h4>

126

127

128

We want to draw a <i>c</i>-oriented polygon, where the angles between

129

successive segments are multiples of

130

30 degrees.

131

The automatic angular snapping mode makes this pretty easy, but there is a

132

little catch: How do we place the ultimate vertex such that it is at the

133

same time properly aligned to the penultimate and to the very first vertex?

134

135

136

</p></div>

137

<ul class="menu"><li>set snap angle to

138

30 degrees,

139

and turn on automatic angular snapping.

140

<li>click first vertex <i>p</i> and draw the polygon up to the penultimate

141

vertex <i>q</i>.

142

<li>it remains to place <i>r</i> such that it is in a legal position both

143

with respect to <i>q</i> and <i>p</i>. The automatic angular snapping

144

mode ensures the position with respect to <i>q</i>. We will use

145

angular snapping from <i>p</i> to get it right: Go near <i>p</i> and

146

turn on vertex snapping. Press <kbd>F1</kbd> to place the origin

147

at <i>p</i> and <kbd>F8</kbd> to turn on angular snapping. Now it is

148

trivial to place <i>r</i>.

149

</ul>

150

<hr />

151

Older »