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      <title>Cut curves and edges</title>
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      <div class="title_topic2" id="xps10_pagetitle">Cut curves and edges</div>
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      <p class="para_topic">Places where the fabric is cut may be represented by curves or edges on the ply surface. Cut entities should ordinarily reach an exterior edge of the ply; this is not required, but a cut entity in the interior of the ply will cause the same problems as holes or cutouts.&nbsp;When mapped to flat pattern space, a cut curve or edge map to two curves, one belonging to the material on either side of the cut. If there is positive Gaussian curvature in the neighborhood of the cut, the cut will correspond to a dart in flat pattern space.</p>
      <div class="title_division">Ply space, stock space, and flat pattern space</div>
      <p class="para_division">There are three spaces involved in the fabric flattener, <b class="uiTerm">Ply Space</b>, <b class="uiTerm">Stock Space</b>, and <b class="uiTerm">Flat Pattern Space</b>.&nbsp;These all have coordinate systems; in ply space and flat pattern space this is specified by the start points and primary and secondary directions, and in flat pattern space by a CSYS.
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      <p class="para_division">Curves and edges may map from one space to another.&nbsp;Ordinarily a flat pattern (in flat pattern space) consists of those edges of the ply covered by the stock and those edges of the stock that fall on the ply.</p>
      <div class="title_division">Mapping ply edges and stock edges</div>
      <p class="para_division">If the stock completely covers the ply (for example, unlimited stock or a large stock) after mapping to the ply space, only ply edges will map to flat pattern space.</p>
      <p class="para_division">If the stock is completely inside the ply, all the stock edges map to ply space and then to flat pattern space. No ply exterior edges will map in this case. Only those ply interior edges covered by stock will map.</p>
      <p class="para_division">If the stock edges partially cover the ply after being mapped to ply (they intersect with each other), the exterior edges of the common area shared by the stock and the ply are mapped to flat pattern space to generate the flat pattern boundary. Only those stock interior edges on the ply (after mapping from stock to ply) are mapped to flat pattern. Same rule applies to ply interior edges.</p>
      <div class="title_division">Mapping additional curves</div>
      <p class="para_division">Additional curves on ply map to the flat pattern space as long as they are inside the ply mesh area.</p>
      <p class="para_division">Additional curves on stock (if any) map to the ply first, then to the flat pattern space. Again, only the part of the curve on the ply mesh will map.</p>
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