plpoly3 - Draw a polygon in 3 space
Contents
Arguments
n (PLINT(3plplot), input) Number of points defining line. x (PLFLT_VECTOR(3plplot), input) A vector containing n x coordinates of points. y (PLFLT_VECTOR(3plplot), input) A vector containing n y coordinates of points. z (PLFLT_VECTOR(3plplot), input) A vector containing n z coordinates of points. draw (PLBOOL_VECTOR(3plplot), input) A vector containing n-1 Boolean values which control 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(3plplot), 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 determined by assuming the points are laid out in a clockwise order.
Description
Draws a polygon in 3 space defined by n points in x, y, and z. Setup like plline3(3plplot), but differs
from that function in that plpoly3(3plplot) attempts to determine if the polygon is viewable depending on
the order of the points within the vector 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(3plplot) 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% accurate... 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.
Name
plpoly3 - Draw a polygon in 3 space
See Also
PLplot documentation at http://plplot.org/documentation.php.
July, 2025 PLPOLY3(3plplot)
Synopsis
plpoly3(n, x, y, z, draw, ifcc)
