Re: Generating Visually Distinct Colors

Perl 6! :) (code slightly adapted to run under Pugs)

#!/usr/bin/perl6
use v6;

# ceil() not yet implemented in Pugs
sub ceil ($n) { int($n) + ($n > int($n) ?? 1 :: 0) }

my $n        = 10;
my $discrete = ceil($n ** (1/3));

my $r = any 0..$discrete-1;
my $g = any 0..$discrete-1;
my $b = any 0..$discrete-1;

# Now $r,$g,$b are Junctions containing all the possible values of
# red/green/blue.
$r = int( (1-$r/$discrete) * 255 );
$g = int( (1-$g/$discrete) * 255 );
$b = int( (1-$b/$discrete) * 255 );

# $color is a Junction containing all colors as "(red, green, blue)".
my $color = "($r, $g, $b)";

# Finally, print $color.
for $color -> $x { say $x }
[download]

Update: Hand-rolled ceil was wrong, fixed (thanks japhy!).

Comment on Re: Generating Visually Distinct Colors Download Code

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Re^2: Generating Visually Distinct Colors by japhy (Canon) on Mar 22, 2005 at 16:46 UTC
Um, what's with that ceil() function? `int($x+2)`? I'd feel much safer with `sub ceil (Num $x) { $x == int($x) ?? $x :: int($x+1) }` [download] I'm pretty sure that's the appropriate P6 code. _____________________________________________________ Jeff `japhy` Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and `perl` hacker How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart	[reply] [d/l] [select]
Re^3: Generating Visually Distinct Colors by polettix (Vicar) on Mar 22, 2005 at 18:47 UTC
In Perl 5, `ceil` is in package POSIX and it is (together with `floor`) the recommended way to do a unilateral round towards an integer. For what I can remember, the use of `int` for this is discouraged even in Perl (5) documentation, due to the fact that its behaviour is not consistent between positive and negative numbers (it only cuts decimals away). I don't know if this has been changed in Perl 6, but I think that I'll stick to the library `ceil` anyway. Flavio -- Don't fool yourself.	[reply] [d/l] [select]
Re^4: Generating Visually Distinct Colors by japhy (Canon) on Mar 22, 2005 at 21:06 UTC
Yes, I use `ceil()`, I was commenting on the very bizarre P6 ceil-equivalent. _____________________________________________________ Jeff `japhy` Pinyan, P.L., P.M., P.O.D, X.S.: Perl, regex, and `perl` hacker How can we ever be the sold short or the cheated, we who for every service have long ago been overpaid? ~~ Meister Eckhart	[reply]
Re^2: Generating Visually Distinct Colors by Roy Johnson (Monsignor) on Mar 22, 2005 at 21:32 UTC
Does that output $n colors, or $n rounded to the next higher cube? Caution: Contents may have been coded under pressure.	[reply]


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