From: Martin Mares <mj@ucw.cz>
Date: Fri, 30 Nov 2007 14:30:59 +0000 (+0100)
Subject: A quick-and-dirty demo of Fortune's algorithm.
X-Git-Url: http://mj.ucw.cz/gitweb/?a=commitdiff_plain;h=73b82638794ec6fd9102c97b9b9a9d93ed334555;p=anim.git

A quick-and-dirty demo of Fortune's algorithm.
---

diff --git a/x.pl b/x.pl
new file mode 100755
index 0000000..0e94b1b
--- /dev/null
+++ b/x.pl
@@ -0,0 +1,142 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+use Gtk2 -init;
+use Cairo;
+
+my $pi = 3.1415926536;
+
+sub para($$$$$) {
+	# draw a parabola y=a(x-x0)^2 + y0
+	my ($cairo,$a,$x0,$y0,$ww) = @_;
+	my $been = 0;
+	for (my $x=0; $x<$ww; $x++) {
+		my $y = $a*($x-$x0)*($x-$x0) + $y0;
+		next if ($y < -10000 || $y > 10000);
+		if ($been++) {
+			$cairo->line_to($x, $y);
+		} else {
+			$cairo->move_to($x, $y);
+		}
+	}
+	$cairo->stroke;
+}
+
+sub solve_para($$$) {
+	my ($h0, $x0, $y0) = @_;
+	my $h = $y0 - $h0;
+	return (1/(2*$h), $x0, $h0 + $h/2);
+}
+
+sub solve_circ($$$$$$) {
+	my ($x0, $y0, $x1, $y1, $x2, $y2) = @_;
+	my $axc = ($x0 + $x1) / 2;
+	my $ayc = ($y0 + $y1) / 2;
+	my $adx = $y1 - $y0;
+	my $ady = $x0 - $x1;
+	my $bxc = ($x1 + $x2) / 2;
+	my $byc = ($y1 + $y2) / 2;
+	my $bdx = $y2 - $y1;
+	my $bdy = $x1 - $x2;
+	my $alpha = (($bxc-$axc)*(-$bdy) - ($byc-$ayc)*(-$bdx)) /
+		    ($adx*(-$bdy) - $ady*(-$bdx));
+	my $x = $axc + $alpha*$adx;
+	my $y = $ayc + $alpha*$ady;
+	my $r = sqrt(($x-$x0)*($x-$x0) + ($y-$y0)*($y-$y0));
+	return ($x, $y, $r);
+}
+
+my $area = Gtk2::DrawingArea->new();
+my $cairo;
+my $dh = 625;
+sub draw() {
+	my $win = $area->window;
+	my $alloc = $area->allocation;
+	my $w = $alloc->width;
+	my $h = $alloc->height;
+
+	$cairo = Gtk2::Gdk::Cairo::Context->create($win);
+	$cairo->rectangle(0, 0, $w, $h);
+	$cairo->set_source_rgb(0, 0, 0);
+	$cairo->fill;
+
+	my @pts = ( [$w/3, $h-600], [$w/2, $h-700], [2*$w/3, $h-650] );
+	my ($cx, $cy, $cr) = solve_circ($pts[0]->[0], $pts[0]->[1], $pts[1]->[0], $pts[1]->[1], $pts[2]->[0], $pts[2]->[1]);
+
+	for (my $i=0; $i<$#pts; $i++) {
+		my $p = $pts[$i];
+		my $q = $pts[$i+1];
+		my $xc = ($p->[0] + $q->[0]) / 2;
+		my $yc = ($p->[1] + $q->[1]) / 2;
+		my $dx = ($q->[1] - $p->[1]);
+		my $dy = ($p->[0] - $q->[0]);
+		$cairo->set_source_rgb(0.5, 0, 0.5);
+		$cairo->move_to($xc - 10*$dx, $yc - 10*$dy);
+		$cairo->line_to($xc + 10*$dx, $yc + 10*$dy);
+		$cairo->stroke;
+		$cairo->set_source_rgb(0.5, 0.5, 0.5);
+		$cairo->move_to($p->[0], $p->[1]);
+		$cairo->line_to($q->[0], $q->[1]);
+		$cairo->stroke;
+	}
+	{
+		my $p = $pts[0];
+		my $q = $pts[2];
+		my $xc = ($p->[0] + $q->[0]) / 2;
+		my $yc = ($p->[1] + $q->[1]) / 2;
+		my $dx = ($q->[1] - $p->[1]);
+		my $dy = ($p->[0] - $q->[0]);
+		$cairo->set_source_rgb(0.5, 0, 0.5);
+		$cairo->move_to($xc - 10*$dx, $yc - 10*$dy);
+		$cairo->line_to($xc + 10*$dx, $yc + 10*$dy);
+		$cairo->stroke;
+		$cairo->set_source_rgb(0.5, 0.5, 0.5);
+		$cairo->move_to($p->[0], $p->[1]);
+		$cairo->line_to($q->[0], $q->[1]);
+		$cairo->stroke;
+	}
+
+	$cairo->set_source_rgb(1, 0, 1);
+	$cairo->arc($cx, $cy, $cr, 0, 2*$pi);
+	$cairo->stroke;
+
+	$cairo->set_source_rgb(1, 1, 1);
+	my $h0 = $h-$dh;
+	$cairo->move_to(0, $h0);
+	$cairo->line_to($w, $h0);
+	$cairo->stroke;
+
+	foreach my $p (@pts) {
+		$cairo->arc($p->[0], $p->[1], 2, 0, 2*$pi);
+		$cairo->fill;
+	}
+
+	$cairo->set_source_rgb(0, 1, 0);
+	foreach my $p (@pts) {
+		next if ($p->[1] > $h0);
+		my ($pa,$px,$py) = solve_para($h0, $p->[0], $p->[1]);
+		para($cairo, $pa, $px, $py, $w);
+	}
+}
+
+my $timer;
+$area->signal_connect("expose-event" => sub {
+	draw();
+});
+
+my $window = Gtk2::Window->new ('toplevel');
+$window->signal_connect ("delete-event" => sub { Gtk2->main_quit });
+$window->set_title("Brum");
+$window->set_wmclass("anim", "Anim");
+$window->set_default_size(640, 480);
+$window->add ($area);
+$window->show_all;
+$window->fullscreen;
+$window->signal_connect("key-press-event" => sub {
+	$dh -= 10;
+	draw();
+});
+
+Gtk2->main;