1PLPOLY3(3plplot)                  PLplot API                  PLPOLY3(3plplot)
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NAME

6       plpoly3 - Draw a polygon in 3 space
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SYNOPSIS

9       plpoly3(n, x, y, z, draw, ifcc)
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DESCRIPTION

12       Draws  a  polygon  in 3 space defined by n points in x, y, and z. Setup
13       like  plline3(3plplot),  but  differs  from  that  function   in   that
14       plpoly3(3plplot)  attempts  to determine if the polygon is viewable de‐
15       pending on the order of the points within the vector and the  value  of
16       ifcc.   If  the  back  of  polygon  is facing the viewer, then it isn't
17       drawn.  If this isn't what you want, then use plline3(3plplot) instead.
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19       The points are assumed to be in a plane, and the directionality of  the
20       plane  is determined from the first three points.  Additional points do
21       not have to lie on the plane defined by the first three, but if they do
22       not, then the determination of visibility obviously can't be 100% accu‐
23       rate... So if you're 3 space polygons are too far from planar, consider
24       breaking them into smaller polygons.  3 points define a plane :-).
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26       Bugs:   If  one of the first two segments is of zero length, or if they
27       are co-linear, the calculation of visibility has a 50/50 chance of  be‐
28       ing  correct.  Avoid such situations :-).  See x18c.c for an example of
29       this problem. (Search for 20.1).
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31       Redacted form: plpoly3(x, y, z, code)
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33       This function is used in example 18.
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ARGUMENTS

36       n (PLINT(3plplot), input)
37              Number of points defining line.
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39       x (PLFLT_VECTOR(3plplot), input)
40              A vector containing n x coordinates of points.
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42       y (PLFLT_VECTOR(3plplot), input)
43              A vector containing n y coordinates of points.
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45       z (PLFLT_VECTOR(3plplot), input)
46              A vector containing n z coordinates of points.
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48       draw (PLBOOL_VECTOR(3plplot), input)
49              A vector containing n-1 Boolean values which control drawing the
50              segments  of  the polygon.  If draw[i] is true, then the polygon
51              segment from index [i] to [i+1] is drawn, otherwise, not.
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53       ifcc (PLBOOL(3plplot), input)
54              If ifcc is true the directionality of the polygon is  determined
55              by  assuming  the points are laid out in a counter-clockwise or‐
56              der.  Otherwise, the directionality of the polygon is determined
57              by assuming the points are laid out in a clockwise order.
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AUTHORS

61       Many  developers  (who  are  credited at http://plplot.org/credits.php)
62       have contributed to PLplot over its long history.
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SEE ALSO

65       PLplot documentation at http://plplot.org/documentation.php.
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69                                 January, 2021                PLPOLY3(3plplot)
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