thank you for the hint to gnuplot; I need the 2D version of the
superformula.
So I took a look at the Perl API at
http://search.cpan.org/~ilyaz/Term-Gnuplot-0.5704/Gnuplot.pm
I hope there is somewhere a tutorial about this because with my
knowledge about Perl based on PerlMagick this API is difficult to
understand. But perhaps there are other options like turtle graphics
where the turtle is controlled by a formula.
Thank you
Günter
There are many tutorials for gnuplot, just google for them.
http://t16web.lanl.gov/Kawano/gnuplot/intro/index-e.html
is one of the better ones. But the best thing to do is run all
the demos that comes with the gnuplot c package.
I had trouble getting the Perl module Term::Gnuplot to
compile on my system, but the latest Gnuplot 4.1 compiles,
and can be run from Perl. You can output to X11 or to a Tk
canvas. Here is a Tk app which will let you adjust the settings
to see the output. For the Tk version, it was easiest for me to
redraw every second, but if you output to X11, you can increase
the efficiency (lower cpu) by using the normal X11 display with the
replot command.
This is fun to play with, and there are some serious "sweet spots"
where unpredictable shapes occur. (Watch for word wrap problems).
#!/usr/bin/perl
#use warnings;
#use strict;
use Tk;
use Tk::ROText;
use IPC::Open3;
$|++;
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 start1{
#for('a1','b1','m1','n1','n2','n3'){
# $scale{$_}->configure( -command => sub{ \&start} );
# }
#&start;
#}
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=$var{'n3'}
# equation below is all one line, watch word wrap)
butterfly(x) = ( ( abs(( (cos(m*x)/4))/a) )**n2 + ( abs((
(sin(m*x)/4))/b) )**n3 )**(-1/n1)
set samples 800
set title "SuperFormula"
unset key
plot butterfly(t)
EOF
print gIN "$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');
}
__END__
