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qsur

       'qsur' <name>(optional) RETURN
       'w'|'a'|'b'|'l'|'i'|'r'|'1'-'9'|'g'|'q'|'u'|'s'|'S'|'h'

This keyword is used to create a surface (see also gsur). The user might specify a name in the command-line or by picking an existing surface with the ''s'' key.

If the surface is supposed to be meshed with unstructured triangles (element type tr3u) it is sufficient to select all lines with the ``l'' key (lowercase ``L''). This can be done either in the ``all''-mode (press ``a'') or ``individual''-mode (press ``i'') which is default. Then generate the surface by pressing the ''g'' key. Such surfaces allow holes in it. If the surface is not plane it will need to reference an embedded NURBS surface (see ''nurs''). It should be noted that this kind of mesh might be extruded in the 3rd dimension by using the ''swep'' command. Otherwhise such surfaces can not be used to define meshable bodies (volumes). Only external meshers might use the triangles as a geometry description (see ''How to deal with cad-geometry'').

For the definition of a regular meshable surface three to five edges must be defined. To create a surface move the mouse pointer over the first line of the first edge and select it with the ''1'' key (number ``one''). If more than one line is necessary to define the first edge select the following ones one after the other with the ''1'' key. Each marked line is listed in the mother xterm. If all lines of the first edge are selected select the lines of the second edge by pressing the ''2'' key, then the third and eventually the fourth and fifth. The last selected line must match the first. All lines defining an edge will create a combined line (see lcmb) and this combined line will show up in the definition of the surface. Then generate the surface by pressing the ''g'' key and you might continue with the next surface. By default the interior of the surface is defined according to Coons [13] which is a blended function. But it can also follow an embedded NURBS-surface or a shape. To relate the surface to an existing NURBS surface select the NURBS surface with the ''S'' key (uppercase) or to a shape with the ``h'' key. Or replace assignments by the blended function with the ''b'' key. To quit the command use the ''q'' key or use ''u'' to undo the last action.

It is also possible to measure distances between two pixels on the screen. Just press the key ''w'' on the positions of the two pixels. The distance is calculated in the scale of the displayed geometry.

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