


PLPOLY3(3)                  PLplot API                 PLPOLY3(3)


NAME
       plpoly3 - Draw a polygon in 3 space

SYNOPSIS
       plpoly3(n, x, y, z, draw, ifcc)

DESCRIPTION
       Draws  a  polygon  in 3 space defined by n points in x, y, and z. Setup
       like plline3(3), but differs from  that  function  in  that  plpoly3(3)
       attempts to determine if the polygon is viewable depending on the order
       of the points within the arrays and the value of ifcc.  If the back  of
       polygon  is facing the viewer, then it isn't drawn.  If this isn't what
       you want, then use plline3(3) instead.

       The points are assumed to be in a plane, and the directionality of  the
       plane  is determined from the first three points.  Additional points do
       not have to lie on the plane defined by the first three, but if they do
       not, then the determination of visibility obviously can't be 100% accu-
       rate... So if you're 3 space polygons are too far from planar, consider
       breaking them into smaller polygons.  3 points define a plane :-).

       Bugs:   If  one of the first two segments is of zero length, or if they
       are co-linear, the calculation of visibility  has  a  50/50  chance  of
       being  correct.   Avoid such situations :-).  See x18c.c for an example
       of this problem. (Search for 20.1).

       Redacted form: plpoly3(x, y, z, code)

       This function is used in example 18.

ARGUMENTS
       n (PLINT, input)
              Number of points defining line.

       x (PLFLT *, input)
              Pointer to array with x coordinates of points.

       y (PLFLT *, input)
              Pointer to array with y coordinates of points.

       z (PLFLT *, input)
              Pointer to array with z coordinates of points.

       draw (PLBOOL *, input)
              Pointer to array which controls  drawing  the  segments  of  the
              polygon.   If  draw[i]  is  true,  then the polygon segment from
              index [i] to [i+1] is drawn, otherwise, not.

       ifcc (PLBOOL, input)
              If ifcc is true the directionality of the polygon is  determined
              by  assuming  the  points  are  laid  out in a counter-clockwise
              order.  Otherwise, the directionality of the polygon  is  deter-
              mined  by assuming the points are laid out in a clockwise order.




                          November, 2007                        1





PLPOLY3(3)                  PLplot API                 PLPOLY3(3)


AUTHORS
       Geoffrey Furnish and Maurice LeBrun wrote and  maintain  PLplot.   This
       man  page  was  automatically  generated from the DocBook source of the
       PLplot  documentation,  maintained  by  Alan  W.   Irwin   and   Rafael
       Laboissiere.

SEE ALSO
       PLplot documentation at http://plplot.sourceforge.net/resources.

















































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