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      <title>Clipping Planes</title>
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      <div class="title_topic4" id="xps10_pagetitle">Clipping Planes</div>
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      <p class="para_topic"> The Front and Back clipping planes are always on for 3D views. (All views, except drawings and views on drawings are 3D views. Drawings and views on drawings are 2D views.)</p>
      <p class="para_topic"> Whenever you create a 3D view, clipping planes are automatically created. This sets up planes that surround the model and are far enough in front of and behind it so that you are able to rotate the model about the center of the viewport without the model intersecting the clipping planes. For a new part, the clipping planes of the eight standard views are created such that a block centered at absolute (0,0,0). With height and width that almost fill the screen, and a depth equal to the greater of the height and width, can be displayed and rotated inside of the clipping planes.</p>
      <p class="para_topic"> The Front Clipping and Back Clipping toggles turn the front and back clipping planes ON and OFF.</p>
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                  <p class="para_note_body">  You cannot remove clipping from 3D (Modeling application) views. The Front Clipping and Back Clipping toggles appear grayed out while in the Modeling application.</p>
                  <p class="para_note_body"></p>
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      <p class="para_topic"> The Distance text field values control the placement of the clipping planes. Choose Fit Planes to Extents to calculate the front and back clipping plane values that fit outside the model extents. After the values are calculated, they are displayed in the Distance text fields. You can then click OK or Apply to update the display.</p>
      <div class="title_division"> Using Clipping Planes</div>
      <p class="para_division"> The clipping planes features allow you to add, change, or remove front and back Z clipping planes. You can use clipping planes to &quot;screen OFF&quot; objects that you do not want visible in a particular view. An alternative to adjusting clipping planes would be to use the Blank/Unblank or Layer options. Both front and back clipping planes must be used in modeling.</p>
      <p class="para_division"> There are two clipping planes: the  <em>front clipping plane</em> and the  <em>back clipping plane</em>. These planes may be used separately or together. Any geometry falling in front of the front clipping plane and behind the back clipping plane is not seen in the view. Only the geometry between the planes is visible.
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                  <p class="para_note_body">It is possible to create objects that fall outside of a view's Z clipping planes. In that case you will not be able to see the newly created objects without first doing a Fit or a Fit Planes to Extents, which resizes the clipping planes. In either case, the system will have to redraw the view.</p>
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      <div class="title_division"> Application Example</div>
      <p class="para_division"> The geometry contained in the layout shown in the following figure appears to be piled on top of itself in the Front view. An inspection of the TFR-TRI view reveals that the three objects have different ZC coordinates in the Front view. In other words, in the Front view the triangular object is closest to the plane of the screen, the cubic object is in the middle, and the hexagonal object is farthest away from the view screen.<img align="bottom" src="graphics/prf_vis_per_clip_no.gif" border="0"></p>
      <p class="para_division"> Front View With No Clipping Planes</p>
      <p class="para_division"> The three figures that follow show the same layout with three different clipping plane arrangements for the Front view.</p>
      <p class="para_division"> In the next figure, the front clipping plane is placed between the triangular and cubic objects. The triangular object is clipped out of theFront view. The clipping plane shown in the TFR-TRI view is shown for descriptive purposes only.</p>
      <p align="center"><img align="bottom" src="graphics/prf_vis_per_clip_with.gif"></p>
      <p class="para_division"> Front View With Front Clipping Plane</p>
      <p align="center"><img align="bottom" src="graphics/prf_vis_per_clip_back.gif"></p>
      <p class="para_division"> In the next figure, the back clipping plane is placed between the cubic and the hexagonal objects. The hexagonal object is clipped out. The clipping plane shown in the TFR-TRI view is shown for descriptive purposes only.</p>
      <p class="para_division"> Front View With Back Clipping Plane</p>
      <p class="para_division"> In the next figure both clipping planes are used. The triangular and hexagonal objects are clipped out. The clipping planes shown in the TFR-TRI view are shown for descriptive purposes only.</p>
      <p align="center"><img align="bottom" src="graphics/prf_vis_per_clip_both.gif"></p>
      <p class="para_division"> Front View With Both Clipping Planes</p>
      <p class="para_division"> You can set clipping planes for each view. Once set, you can always remove them.</p>
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            <td valign="top" align="left"><img align="left" src="../graphics/note.gif" alt="Note" title="Note"></td>
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               <div class="para_note">
                  <p class="para_note_body">  You cannot remove clipping planes for 3-D views.</p>
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      <p class="para_division"> These settings are saved with the part file. When a new view is created, Front and Back Clipping are initialized to On, and the Distances are initialized to the model extents.</p>
      <div class="title_division">Disable Auto Front and Back Clipping Planes Update</div>
      <p class="para_division">Controls whether a Fit operation automatically updates the front and back clipping planes. If the option is turned on, a Fit operation does not modify clipping planes. If the option is turned off, a Fit operation adjusts front and back clipping planes to ensure all visible model geometry lies between the planes, with some extra depth to permit you to rotate the view without inadvertently clipping the model. You may wish to turn on the option to ensure that clipping planes remain at fixed locations or to ensure that clipping planes remain far enough from model geometry so the model remains unclipped even when additional geometry is displayed. </p>
      <div class="title_division">Automatic Inclusion of Components within Front and Back Clipping Planes</div>
      <p class="para_division">Controls whether the system, when displaying a component, automatically updates front and back clipping planes to ensure the newly displayed component is visible. If the option is turned on, the system updates the clipping planes of displayed views for the following operations, among others. </p>
      <ul>
         <li>
            <p class="para_item">Add a component to an assembly.</p>
         </li>
         <li>
            <p class="para_item">Load an unloaded component.</p>
         </li>
         <li>
            <p class="para_item">Unblank a component.</p>
         </li>
         <li>
            <p class="para_item">Change the displayed reference set of a component. </p>
         </li>
      </ul>
      <p class="para_division">The system enables this option by default at the start of each session and provides no dialog control to change the setting. To disable the option by default, set the following environment variable before starting NX. </p><pre class="indent">UGII_DISABLE_UPDATE_Z_CLIP_FOR_COMPONENT=1</pre></body>
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