#!/usr/bin/perl -w
#
# Example 9-6. Drawing a circle with cubic Bezier curves

use strict;
use SWF::Shape;

SWF::setScale(1.0);

my $PI = 3.1415926535;      # pi
my $r = 50;                 # the radius
my $start = 0;              # start angle
my $end = 0;                # end angle
my $segments = 6;           # number of segments

# Create a new Shape object

my $s = new SWF::Shape();
$s->setLineStyle(1, 255, 0, 0);
$s->movePenTo($r,0);

for (my $end=360/$segments; $end<=360; $end+=360/$segments) {

    # Calculate the midpoint angle. The control point
    # lies on this line
    
    my $midpoint = $start+($end-$start)/2;

    # draw_arc() draws a circular arc between 2 points

    draw_arc($s,
         $r*cos(radians($start)),$r*sin(radians($start)),
         $r*cos(radians($end)), $r*sin(radians($end)),
         radians($midpoint)); 
    $start=$end;
}
    
# Create a Movie to hold the Shape

my $m = new SWF::Movie();
$m->setDimension(300, 300);
my $item = $m->add($s);
$item->moveTo(100,100);
$m->nextFrame();

$m->save('circle.swf');

exit;

sub draw_arc {
    
    # Take a shape, a start coordinate, end coordinate and
    # pre-computed mid-point angle as arguments
    
    my ($s, $x1, $y1, $x2, $y2, $angle) = @_;
    my $cx = 2*($r*cos($angle)-.25*$x1-.25*$x2);
    my $cy = 2*($r*sin($angle)-.25*$y1-.25*$y2);

    # Draw the curve on the Shape
    
    $s->drawCurveTo($cx, $cy, $x2, $y2);
}

sub radians {
    return ($_[0]/180)*$PI;      # Convert to radians
}