=head1 Vector2
Manipulate 2D vectors
PhilipRBrenan@yahoo.com, 2004, Perl License
=head2 Synopsis
Example t/vector2.t
#_ Vector _____________________________________________________________
# Test 2d vectors
# philiprbrenan@yahoo.com, 2004, Perl License
#______________________________________________________________________
use Math::Zap::Vector2 vector2=>v, units=>u;
use Test::Simple tests=>7;
my ($x, $y) = u();
ok(!$x == 1);
ok(2*$x+3*$y == v( 2, 3));
ok(-$x-$y == v(-1, -1));
ok((2*$x+3*$y) + (-$x-$y) == v( 1, 2));
ok((2*$x+3*$y) * (-$x-$y) == -5);
ok($x*2 == v( 2, 0));
ok($y/2 == v( 0, 0.5));
=head2 Description
Manipulate 2D vectors
=cut
package Math::Zap::Vector2;
$VERSION=1.07;
use Math::Trig;
use Carp;
use constant debug => 0; # Debugging level
=head2 Constructors
=head3 new
Create a vector from numbers
=cut
sub new($$)
{return bless {x=>$_[0], y=>$_[1]} unless debug;
my ($x, $y) = @_;
round(bless({x=>$x, y=>$y}));
}
=head3 vector2
Create a vector from numbers - synonym for L</new>
=cut
sub vector2($$) {new($_[0],$_[1])}
=head3 units
Unit vectors
=cut
$x = new(1,0);
$y = new(0,1);
sub units() {($x, $y)}
=head2 Methods
=head3 check
Check its a vector
=cut
sub check(@)
{if (debug)
{for my $v(@_)
{confess "$v is not a vector2" unless ref($v) eq __PACKAGE__;
}
}
return (@_)
}
=head3 is
Test its a vector
=cut
sub is(@)
{for my $v(@_)
{return 0 unless ref($v) eq __PACKAGE__;
}
1;
}
=head3 accuracy
Get/Set accuracy for comparisons
=cut
my $accuracy = 1e-10;
sub accuracy
{return $accuracy unless scalar(@_);
$accuracy = shift();
}
=head3 round
Round: round to nearest integer if within accuracy of that integer
=cut
sub round($)
{unless (debug)
{return $_[0];
}
else
{my ($a) = @_;
for my $k(keys(%$a))
{my $n = $a->{$k};
my $N = int($n);
$a->{$k} = $N if abs($n-$N) < $accuracy;
}
return $a;
}
}
=head3 components
x,y components of vector
=cut
sub x($) {check(@_) if debug; $_[0]->{x}}
sub y($) {check(@_) if debug; $_[0]->{y}}
=head3 clone
Create a vector from another vector
=cut
sub clone($)
{my ($v) = check(@_); # Vectors
round bless {x=>$v->x, y=>$v->y};
}
=head3 length
Length of a vector
=cut
sub length($)
{check(@_[0..0]) if debug; # Vectors
sqrt($_[0]->{x}**2+$_[0]->{y}**2);
}
=head3 print
Print vector
=cut
sub print($)
{my ($v) = check(@_); # Vectors
my ($x, $y) = ($v->x, $v->y);
"vector2($x, $y)";
}
=head3 normalize
Normalize vector
=cut
sub norm($)
{my ($v) = check(@_); # Vectors
my $l = $v->length;
$l > 0 or confess "Cannot normalize zero length vector $v";
new($v->x / $l, $v->y / $l);
}
=head3 rightAngle
At right angles
=cut
sub rightAngle($)
{my ($v) = check(@_); # Vectors
new(-$v->y, $v->x);
}
=head3 dot
Dot product
=cut
sub dot($$)
{my ($a, $b) = check(@_); # Vectors
$a->x*$b->x+$a->y*$b->y;
}
=head3 angle
Angle between two vectors
=cut
sub angle($$)
{my ($a, $b) = check(@_); # Vectors
acos($a->norm->dot($b->norm));
}
=head3 add
Add vectors
=cut
sub add($$)
{my ($a, $b) = check(@_); # Vectors
new($a->x+$b->x, $a->y+$b->y);
}
=head3 subtract
Subtract vectors
=cut
sub subtract($$)
{check(@_) if debug; # Vectors
new($_[0]->{x}-$_[1]->{x}, $_[0]->{y}-$_[1]->{y});
}
=head3 multiply
Vector times a scalar
=cut
sub multiply($$)
{my ($a) = check(@_[0..0]); # Vector
my ($b) = @_[1..1]; # Scalar
confess "$b is not a scalar" if ref($b);
new($a->x*$b, $a->y*$b);
}
=head3 divide
Vector divided by a non zero scalar
=cut
sub divide($$)
{my ($a) = check(@_[0..0]); # Vector
my ($b) = @_[1..1]; # Scalar
confess "$b is not a scalar" if ref($b);
confess "$b is zero" if $b == 0;
new($a->x/$b, $a->y/$b);
}
=head3 equals
Equals to within accuracy
=cut
sub equals($$)
{my ($a, $b) = check(@_); # Vectors
abs($a->x-$b->x) < $accuracy and
abs($a->y-$b->y) < $accuracy;
}
=head2 Operators
# Operator overloads
=cut
use overload
'+' => \&add3, # Add two vectors
'-' => \&subtract3, # Subtract one vector from another
'*' => \&multiply3, # Times by a scalar, or vector dot product
'/' => \÷3, # Divide by a scalar
'<' => \&angle3, # Angle in radians between two vectors
'>' => \&angle3, # Angle in radians between two vectors
'==' => \&equals3, # Equals
'""' => \&print3, # Print
'!' => \&length, # Length
'fallback' => FALSE;
=head3 add
Add operator.
=cut
sub add3
{my ($a, $b) = @_;
$a->add($b);
}
=head3 subtract
Subtract operator.
=cut
sub subtract3
{#my ($a, $b, $c) = @_;
#return $a->subtract($b) if ref($b);
return new($_[0]->{x}-$_[1]->{x}, $_[0]->{y}-$_[1]->{y}) if ref($_[1]);
new(-$_[0]->{x}, -$_[0]->{y});
}
=head3 multiply
Multiply operator.
=cut
sub multiply3
{my ($a, $b) = @_;
return $a->dot ($b) if ref($b);
return $a->multiply($b);
}
=head3 divide
Divide operator.
=cut
sub divide3
{my ($a, $b, $c) = @_;
return $a->divide($b);
}
=head3 angle
Angle between two vectors.
=cut
sub angle3
{my ($a, $b, $c) = @_;
return $a->angle($b);
}
=head3 equals
Equals operator.
=cut
sub equals3
{my ($a, $b, $c) = @_;
return $a->equals($b);
}
=head3 print
Print a vector.
=cut
sub print3
{my ($a) = @_;
return $a->print;
}
=head2 Exports
Export L</vector2>, L</units>, L</check>, L</is>
=cut
use Math::Zap::Exports qw(
vector2 ($$)
units ()
check (@)
is (@)
);
#_ Vector2 ____________________________________________________________
# Package loaded successfully
#______________________________________________________________________
1;
=head2 Credits
=head3 Author
philiprbrenan@yahoo.com
=head3 Copyright
philiprbrenan@yahoo.com, 2004
=head3 License
Perl License.
=cut
