A newsgroup post got me going on this. It is a way to quickly visualize the
SuperFormula using PerlTk and IPC. I had trouble getting
Term::GnuPlot to compile, but the latest
gnuplot has Tk output built in (although not as efficient as the X11 driver, see commented out line).
The output for Tkcanvas requires evaling a string and generating subs, so it dosn't run with strict, and I've commented out warnings, to eliminate some harmless warnings. It prints '0 0 0 0' upon finishing a graph cycle.
This has 1 guarantee.... it will become addicting and waste alot of your time. :-) There are some very interesting "sweetspots" in the adjustments.
#!/usr/bin/perl
#use warnings;
#use strict;
use Tk;
use Tk::ROText;
use IPC::Open3;
# see http://en.wikipedia.org/wiki/Superformula
# for the formula
$|++;
my %var =(
'a1'=> 1,
'b1'=> 1,
'm1'=> 8,
'n1'=> 1,
'n2'=> 1,
'n3'=> 1,
);
my $stop = 0;
my $repeater;
my $running = 0;
my $mw = MainWindow->new;
my $tframe = $mw->Frame()->pack();
my $canvas = $tframe->Canvas(
-bg => 'white',
-height =>500,
-width =>500,
)->pack(-side=>'left',-expand=>1,-fill=>'both');
my $tframe1 = $tframe->Frame()->pack(-side=>'right',-padx=>0);
my %scale;
for ('a1','b1','m1','n1','n2','n3'){
my $tframea = $tframe1->Frame()->pack(-side=>'left',-padx=>0);
$tframea->Label(-text => " $_ ")->pack(-side=>'top');
$scale{$_} = $tframea->Scale(
-from => -100,
-to => 100,
-length => 500,
-orient => 'vertical',
-variable => \$var{$_},
-resolution => .01,
-borderwidth =>0,
-foreground => 'white',
-background => 'lightslategrey',
-troughcolor => 'powderblue',
)->pack(-side => 'left', -padx=>0);
}
my $text = $mw->Scrolled('ROText',
-bg=>'white',
-height =>5,
-width => 45)
->pack( -fill => 'both', -expand => 1 );
tie(*STDOUT, 'Tk::Text', $text);
$text->tagConfigure( 'red', -foreground => 'red' );
my $pid = open3( \*gIN, \*gOUT, \*gERR, "/usr/bin/gnuplot" ) || die;
$mw->fileevent( \*gOUT, readable => \&read_out );
$mw->fileevent( \*gERR, readable => \&read_err );
#comment out the below line to get gnuplot's X11 display
#which is more efficient than the canvas plot
print gIN "set term tkcanvas perltk interactive\n";
my $bframe = $mw->Frame->pack();
my $startbut = $bframe->Button(
-text=>'Start',
-command=> \&start)->pack(-side=>'left');
my $stopbut = $bframe->Button(
-text=>'Stop',
-command=> sub{ $auto = 0;
$repeater->cancel;
$running = 0;
})->pack(-side=>'left');
#must be last or get broken pipe error
tie(*STDERR, 'Tk::Text', $text);
$mw->update;
MainLoop;
sub start{
my $string =<<"EOF";
reset
unset border
set clip
set polar
set xtics axis nomirror
set ytics axis nomirror
set zeroaxis
set trange [0:2*pi]
a=$var{'a1'}
b=$var{'b1'}
m=$var{'m1'}
n1=$var{'n1'}
n2=$var{'n2'}
n3=$var{'n3'}
butterfly(x) = ( ( abs(( (cos(m*x)/4))/a) )**n2 + ( abs(( (sin(m*x)/
+4))/b) )**n3 )**(-1/n1)
set samples 800
set title "SuperFormula"
unset key
plot butterfly(t)
EOF
print gIN "$string\n";
if( $running == 0){
$repeater=$mw->repeat(1000,sub{
$running = 1;
&start;
});
}
}
sub read_out {
my $buffer = <gOUT>;
# print $buffer,"\n";
my $can = $canvas;
eval($buffer);
}
sub read_err {
# print "read_err()\n";
my $num = sysread(gERR, my $buffer, 1024 );
# print "sysread() got $num bytes:\n[$buffer]\n";
$text->insert( 'end', $buffer, 'red' );
$text->see('end');
}