#!/usr/bin/perl
use strict;
use warnings;

die "syntax: farbverlauf.pl anzahl startfarbe endfarbe\n" unless 3 == @ARGV;
my @color = farbverlauf(@ARGV);

print '[color=', $_, ']', $_, '[/color]', "\n" for @color;
exit;


sub farbverlauf {
    my ($n, $von, $bis) = @_;


    my ($f1, $f2, $f3) = $von =~ /^#?([0-9abcdef]{2})([0-9abcdef]{2})([0-9abcdef]{2})$/i;
    my ($f4, $f5, $f6) = $bis =~ /^#?([0-9abcdef]{2})([0-9abcdef]{2})([0-9abcdef]{2})$/i;

    my $ar = hex $f1; # Anfangsfarbwerte
    my $ag = hex $f2;
    my $ab = hex $f3;

    my $zr = hex $f4; # Endfarbwerte
    my $zg = hex $f5;
    my $zb = hex $f6;

    my $dr = ($zr-$ar) / ($n-1); # Deltawerte
    my $dg = ($zg-$ag) / ($n-1);
    my $db = ($zb-$ab) / ($n-1);

    #print "ar=$ar\tag=$ag\tab=$ab\n",
    #      "zr=$zr\tzg=$zg\tzb=$zb\n",
    #      "dr=$dr\tdg=$dg\tdb=$db\n";

    my $r = $ar;
    my $g = $ag;
    my $b = $ab;

    my @ergebnis;
    for my $i (1 .. $n) {
        my $rr = int $r+.5;
        my $gg = int $g+.5;
        my $bb = int $b+.5;
        
        push @ergebnis, sprintf "#%02X%02X%02X", $rr, $gg, $bb;

        $r += $dr;
        $g += $dg;
        $b += $db;
    }

    return @ergebnis;
} # sub farbverlauf

[color=#FF0000]#FF0000[/color]
[color=#E31C00]#E31C00[/color]
[color=#C63900]#C63900[/color]
[color=#AA5500]#AA5500[/color]
[color=#8E7100]#8E7100[/color]
[color=#718E00]#718E00[/color]
[color=#55AA00]#55AA00[/color]
[color=#39C600]#39C600[/color]
[color=#1CE300]#1CE300[/color]
[color=#00FF00]#00FF00[/color]