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      <title>Haystack geometry</title>
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      <div class="title_topic3" id="xps10_pagetitle">Haystack geometry</div>
      <hr noshade="true"><a name="ndxgenid_roadmap314"></a><p class="para_topic"><img align="bottom" src="graphics/commandref/ideas_rule.gif" border="0"></p>
      <p class="para_topic">It's often convenient to sketch extra construction lines and other overlapping &ldquo;haystack&rdquo; geometry that isn't part of the feature to be created. In I-deas, it's customary to leave this haystack geometry in the sketch and use Selection Intent options to pick only the desired curves to create the feature.</p>
      <p class="para_topic"><img align="bottom" src="graphics/commandref/nx_rule.gif" border="0"></p>
      <p class="para_topic">In NX, there are three methods to deal with this extra haystack geometry:</p>
      <ul>
         <li>
            <p class="para_item">Trim curves to remove haystack geometry.</p>
         </li>
         <li>
            <p class="para_item">Convert construction geometry to reference curves.</p>
         </li>
         <li>
            <p class="para_item">Use Selection Intent options as in I-deas.</p>
         </li>
      </ul><a name="qt_parts_trimming"></a><a name="ndxgenid_roadmap315"></a><a name="ndxgenid_roadmap316"></a><div class="title_division">Trimming curves</div>
      <p class="para_division">If you trim away overlapping geometry instead of using Selection Intent rules when you create a feature, it may save time because the entire sketch can be selected.</p>
      <p class="para_division">Use the buttons <b class="uiTerm">Quick Trim</b> and <b class="uiTerm">Quick Extend</b> in the <b class="uiTerm">Sketch Curve</b> toolbar to trim curves.
      </p>
      <ul class="unmarkedList">
         <li>
            <p class="para_item"><img align="bottom" src="graphics/icons/icon_quick_trim.gif" border="0"> <b class="uiTerm">Quick Trim</b></p>
         </li>
         <li>
            <p class="para_item"><img align="bottom" src="graphics/icons/icon_quick_extend.gif" border="0"> <b class="uiTerm">Quick Extend</b></p>
         </li>
      </ul>
      <p align="center"><img align="bottom" src="graphics/parts/trim_anim.gif"></p><a name="qt_parts_reference_curves"></a><a name="ndxgenid_roadmap317"></a><div class="title_division">Reference curves</div>
      <p class="para_division">In NX, reference curves in a sketch are not used when a feature is created. They can be used for construction lines and center lines.</p>
      <p align="center"><img align="bottom" src="graphics/parts/reference-curve-pic.gif"></p>
      <p class="para_division">To convert regular sketch curves to reference curves, use the command:</p>
      <ul class="unmarkedList">
         <li>
            <p class="para_item"><img align="bottom" src="graphics/icons/icon_convert_to_from_reference.gif" border="0"> <b class="uiTerm">Convert To/From Reference</b> (<b class="uiTerm">Sketch Curve</b> toolbar)
            </p>
         </li>
      </ul>
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               <div class="para_tip">
                  <p class="para_tip_body">In I-deas, sketches are converted to reference curves so they can be used in multiple features. In NX, all sketches can be used in multiple features. NX reference curves are the sketch curves that do NOT become part of the feature geometry. Reference curves are used as construction lines to create constraints, such as using center lines to position circles.</p>
               </div>
            </td>
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      </table><a name="qt_parts_selection_intent"></a><a name="ndxgenid_roadmap318"></a><a name="ndxgenid_roadmap319"></a><div class="title_division">Selection Intent</div>
      <p class="para_division">Features like <b class="uiTerm">Extrude</b>, <b class="uiTerm">Edge Blend</b>, and <b class="uiTerm">Draft</b> use Selection Intent options.
      </p>
      <p class="para_division">Selection Intent options are found on the Selection Bar. </p>
      <p align="center"><img align="bottom" src="graphics/icons/selection_intent_toolbar.gif"></p>
      <ul>
         <li>
            <p class="para_item">Use the pull-down menu to define curve options such as picking single curves or chaining tangent curves in the sketch.</p>
         </li>
         <li>
            <p class="para_item">Use the toolbar buttons to select the options <b class="uiTerm">Stop At Intersection</b> and <b class="uiTerm">Follow Fillets</b>.
            </p>
         </li>
      </ul>
      <p class="para_division">See also:</p>
      <ul class="unmarkedList">
         <li>
            <p class="para_item">Help: <img align="bottom" src="graphics/widgets/book_closed.gif" border="0"> Design &rarr; Sketcher
            </p>
         </li>
         <li>
            <p class="para_item">Help: <img align="bottom" src="graphics/widgets/book_closed.gif" border="0"> Design &rarr; Modeling &rarr;  Methods in Feature Modeling &rarr; Selection
            </p>
         </li>
      </ul>
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