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(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 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(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.
ARGUMENTS¶
- n (PLINT, input)
- Number of points defining line.
- x (const PLFLT *, input)
- Pointer to array with x coordinates of points.
- y (const PLFLT *, input)
- Pointer to array with y coordinates of points.
- z (const PLFLT *, input)
- Pointer to array with z coordinates of points.
- draw (const 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 determined by assuming the points are
laid out in a clockwise order.
AUTHORS¶
Many developers (who are credited at
http://plplot.sourceforge.net/credits.php)
have contributed to PLplot over its long history.
SEE ALSO¶
PLplot documentation at
http://plplot.sourceforge.net/documentation.php.