X-Git-Url: http://git.shiar.nl/sheet.git/blobdiff_plain/f0d06e6376cc06a0876f83015fc7731e32b081d9..1f3b44e51107dc97ce2bded07b93325e96835744:/Shiar_Sheet/Colour.pm

diff --git a/Shiar_Sheet/Colour.pm b/Shiar_Sheet/Colour.pm
index 7ea68e9..cedfdfb 100644
--- a/Shiar_Sheet/Colour.pm
+++ b/Shiar_Sheet/Colour.pm
@@ -4,13 +4,15 @@ use strict;
 use warnings;
 use List::Util qw( min max );
 
-our $VERSION = '1.01';
+our $VERSION = '1.02';
 
 # ITU-R recommendation 601 luma co-efficients
 our $kr = .299;
 our $kb = .114;
 our $kg = 1 - $kb - $kr;
 
+my $PI = 2 * atan2 1, 0;
+
 sub new {
 	my $class = shift;
 	my @rgb = @_ >= 3 ? @_ : (map {hex} $_[0] =~ /(..)/g);
@@ -39,6 +41,12 @@ sub luminance {
 	return $r*$kr + $g*$kg + $b*$kb;
 }
 
+sub hue {
+	my ($r, $g, $b) = @{ $_[0] };
+	my $hue = atan2 sqrt(3) * ($g - $b), $r*2 - $g - $b;
+	return ($hue + $PI) / $PI / 2; # 0 .. 1
+}
+
 sub rgb24 {
 	my $str = '';
 	$str .= sprintf '%X', min($_ / 17 + .5, 15) for @{ $_[0] };