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# Author: Chao-Kuei Hung
# For more info, including license, please see doc/index.html
package Vector3;
# 3-d Vector
use strict;
use Carp;
use vars qw(@ISA);
@ISA = qw(Vector);
use Vector;
sub cross {
# cross product
my ($self, $other) = @_;
return Vector->new(
$self->y*$other->z-$self->z*$other->y,
$self->z*$other->x-$self->x*$other->z,
$self->x*$other->y-$self->y*$other->x,
);
}
sub rotate_around {
# rotate $self around $axis by $th
my ($self, $axis, $th) = @_;
my ($x, $r, $p);
$r = $axis->norm();
return $self if $r < 1e-5;
$x = $axis->pw_div($r);
$r = $x->pw_mul($self->dot($x));
$p = $self - $r;
return $r + $p->pw_mul(cos($th)) + $x->cross($p)->pw_mul(sin($th));
}
if ($0 =~ /Vector3.pm$/) {
# being tested as a stand-alone program, so run test code.
my ($p, $q);
$p = Vector3->new(1,1,0);
$q = Vector3->new(1,1,1);
print $p->cross($q), "\n";
# ans: [1, -1, 0]
print $p->rotate_around($q, atan2(1,1)*8/3), "\n";
# ans: [0, 1, 1]
}
1;
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