http://www.perlmonks.org?node_id=591387

I found this old toy while cleaning out the closet and thought some might find it interesting. It is an experiment to see what kinds of images can be made from Moire-like patterns. Output is a png image, so redirect to a file, or uncomment the Content-Type header line and run as a CGI program.

YuckFoo

#!/usr/bin/perl use strict; use GD; use POSIX; #--------------------------------------- # conf my $conf = { image => { x_size => 320, y_size => 320, }, palette => { num_colors => int(rand(56) + 8), set_points => [ [0, 0, 0], [int(rand(255)), int(rand(255)), int(rand(255))], [0, 0, 0], [255, 255, 255], [0, 0, 0], [int(rand(255)), int(rand(255)), int(rand(255))], ], repeat => rand(1.5) + .5, }, moire => { num_lines => int(rand(7)) + 2, repeat_min => 4, repeat_max => 8, wrap_prob => rand(), turn_prob => rand(), plot => int(rand(2)), }, }; #--------------------------------------- # init my $palette = setup_palette($conf->{palette}); my $moire = setup_moire($conf->{moire}); my $image = new GD::Image($conf->{image}{x_size}, $conf->{image}{y +_size}); for my $col (@$palette) { $image->colorAllocate($col->[0], $col->[1], $col->[2]); } #--------------------------------------- # go make_image($conf, $moire, $image); #print "Content-Type: image/png \n\n"; print $image->png(); #----------------------------------------------------------- sub make_image { my $conf = shift; my $moire = shift; my $image = shift; my $x_pix = 1 / $conf->{image}{x_size}; my $y_pix = 1 / $conf->{image}{y_size}; my $max; for my $line (@$moire) { if ($line->{wrap}) { $max += 1; } else { $max += .5; } } for my $xi (0..$conf->{image}{x_size}-1) { my $x = $xi * $x_pix; for my $yi (0..$conf->{image}{y_size}-1) { my $y = $yi * $y_pix; my $tot; for my $line (@$moire) { my $val = $x + $y * $line->{grad}; $val = $val * $line->{mult}; $val = $val - floor($val); if ($line->{wrap}) { if ($val > .5) { $val = 1 - $val; } } if ($line->{turn}) { $val = 1 - $val; } $tot += $val; } $tot = $conf->{moire}{plot} ? ($tot / $max) * $conf->{palette}{repeat} : $tot / @$moire; my $ci = $tot * $conf->{palette}{num_colors}; $image->setPixel($xi, $yi, $ci % $conf->{palette}{num_colors}); } } } #----------------------------------------------------------- sub setup_moire { my $conf = shift; my @lines; for (1..$conf->{num_lines}) { my $line = {}; push (@lines, $line); $line->{mult} = rand($conf->{repeat_max} - $conf->{repeat_min}); $line->{mult} = int($line->{mult} + $conf->{repeat_min}); $line->{wrap} = (rand() < $conf->{wrap_prob}) ? 1 : 0; $line->{turn} = (rand() < $conf->{turn_prob}) ? 1 : 0; $line->{grad} = rand(2); if ($line->{grad} > 1) { $line->{grad} = 1 / ($line->{grad} - 1); } if (int(rand(2))) { $line->{grad} *= -1; } } return \@lines; } #----------------------------------------------------------- sub setup_palette { my $conf = shift; my @palette_colors; my @palette_indexs; push @{$conf->{set_points}}, $conf->{set_points}[0]; my $rate = $conf->{num_colors} / $#{$conf->{set_points}}; for my $i (0 .. $#{$conf->{set_points}}) { my $j = int($i * $rate); push @palette_indexs, $j; $palette_colors[$j] = $conf->{set_points}[$i]; } for my $i (0 .. $#palette_indexs - 1) { my $beg = $palette_indexs[$i]; my $end = $palette_indexs[$i+1]; interpolate(\@palette_colors, $beg, $end); } pop @palette_colors; return \@palette_colors; } #----------------------------------------------------------- sub interpolate { my $colors = shift; my $beg = shift; my $end = shift; my $steps = $end - $beg; my $r_start = $colors->[$beg][0]; my $r_range = $colors->[$end][0] - $colors->[$beg][0]; my $r_slope = $r_range / $steps; my $g_start = $colors->[$beg][1]; my $g_range = $colors->[$end][1] - $colors->[$beg][1]; my $g_slope = $g_range / $steps; my $b_start = $colors->[$beg][2]; my $b_range = $colors->[$end][2] - $colors->[$beg][2]; my $b_slope = $b_range / $steps; for my $i (1..$steps-1) { my $j = $i + $beg; $colors->[$j][0] = int($r_start + ($i * $r_slope)); $colors->[$j][1] = int($g_start + ($i * $g_slope)); $colors->[$j][2] = int($b_start + ($i * $b_slope)); } }