1PLPOLY3(3plplot)                  PLplot API                  PLPOLY3(3plplot)
2
3
4

NAME

6       plpoly3 - Draw a polygon in 3 space
7

SYNOPSIS

9       plpoly3(n, x, y, z, draw, ifcc)
10

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
15       depending 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.
18
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 :-).
25
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
28       being  correct.   Avoid such situations :-).  See x18c.c for an example
29       of this problem. (Search for 20.1).
30
31       Redacted form: plpoly3(x, y, z, code)
32
33       This function is used in example 18.
34

ARGUMENTS

36       n (PLINT(3plplot), input)
37              Number of points defining line.
38
39       x (PLFLT_VECTOR(3plplot), input)
40              A vector containing n x coordinates of points.
41
42       y (PLFLT_VECTOR(3plplot), input)
43              A vector containing n y coordinates of points.
44
45       z (PLFLT_VECTOR(3plplot), input)
46              A vector containing n z coordinates of points.
47
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.
52
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
56              order.  Otherwise, the directionality of the polygon  is  deter‐
57              mined by assuming the points are laid out in a clockwise order.
58
59

AUTHORS

61       Many    developers   (who   are   credited   at   http://plplot.source‐
62       forge.net/credits.php) have contributed to PLplot over  its  long  his‐
63       tory.
64

SEE ALSO

66       PLplot    documentation   at   http://plplot.sourceforge.net/documenta‐
67       tion.php.
68
69
70
71                                 August, 2017                 PLPOLY3(3plplot)
Impressum