table of contents
Bezier(3pm) | User Contributed Perl Documentation | Bezier(3pm) |
NAME¶
Math::Bezier - solution of Bezier CurvesSYNOPSIS¶
use Math::Bezier; # create curve passing list of (x, y) control points my $bezier = Math::Bezier->new($x1, $y1, $x2, $y2, ..., $xn, $yn); # or pass reference to list of control points my $bezier = Math::Bezier->new([ $x1, $y1, $x2, $y2, ..., $xn, $yn]); # determine (x, y) at point along curve, range 0 -> 1 my ($x, $y) = $bezier->point(0.5); # returns list ref in scalar context my $xy = $bezier->point(0.5); # return list of 20 (x, y) points along curve my @curve = $bezier->curve(20); # returns list ref in scalar context my $curve = $bezier->curve(20);
DESCRIPTION¶
This module implements the algorithm for the solution of Bezier curves as presented by Robert D. Miller in Graphics Gems V, "Quick and Simple Bezier Curve Drawing".A new Bezier curve is created using the new() constructor, passing a list of (x, y) control points.
use Math::Bezier; my @control = ( 0, 0, 10, 20, 30, -20, 40, 0 ); my $bezier = Math::Bezier->new(@control);
Alternately, a reference to a list of control points may be passed.
my $bezier = Math::Bezier->new(\@control);
The point($theta) method can then be called on the object, passing a value in the range 0 to 1 which represents the distance along the curve. When called in list context, the method returns the x and y coordinates of that point on the Bezier curve.
my ($x, $y) = $bezier->point(0.5); print "x: $x y: $y\n
When called in scalar context, it returns a reference to a list containing the x and y coordinates.
my $point = $bezier->point(0.5); print "x: $point->[0] y: $point->[1]\n";
The curve($n) method can be used to return a set of points sampled along the length of the curve (i.e. in the range 0 <= $theta <= 1). The parameter indicates the number of sample points required, defaulting to 20 if undefined. The method returns a list of ($x1, $y1, $x2, $y2, ..., $xn, $yn) points when called in list context, or a reference to such an array when called in scalar context.
my @points = $bezier->curve(10); while (@points) { my ($x, $y) = splice(@points, 0, 2); print "x: $x y: $y\n"; } my $points = $bezier->curve(10); while (@$points) { my ($x, $y) = splice(@$points, 0, 2); print "x: $x y: $y\n"; }
AUTHOR¶
Andy Wardley <abw@kfs.org>SEE ALSO¶
Graphics Gems 5, edited by Alan W. Paeth, Academic Press, 1995, ISBN 0-12-543455-3. Section IV.8, 'Quick and Simple Bezier Curve Drawing' by Robert D. Miller, pages 206-209.2016-01-05 | perl v5.22.1 |