#!/usr/local/bin/perl -w
# -*- perl -*-

#
# $Id: VectorUtil.pm,v 1.14 2003/10/01 22:31:36 eserte Exp $
# Author: Slaven Rezic
#
# Copyright (C) 1999,2001 Slaven Rezic. All rights reserved.
# This program is free software; you can redistribute it and/or
# modify it under the same terms as Perl itself.
#
# Mail: slaven@rezic.de
# WWW:  http://bbbike.sourceforge.net
#

package VectorUtil;

use strict;
use vars qw($VERSION $VERBOSE @ISA @EXPORT_OK);
$VERSION = sprintf("%d.%02d", q$Revision: 1.14 $ =~ /(\d+)\.(\d+)/);

require Exporter;
@ISA = 'Exporter';

@EXPORT_OK = qw(vector_in_grid distance_point_line get_polygon_center
		point_in_grid);

# Diese Funktion testet, ob sich ein Vektor innerhalb eines Gitters
# befindet. Für Vektoren, bei denen mindestens einer der Punkte innerhalb
# des Gitters ist, ist die Lösung trivial. Interessanter ist es, wenn
# beide Punkte außerhalb des Gitters sind, ein Teil des Vektors aber
# innerhalb.
# Siehe auch Grafik in ../misc/gridvectortest.fig
sub vector_in_grid {
    my($x1,$y1,$x2,$y2,$gridx1,$gridy1,$gridx2,$gridy2) = @_;

    # wenigstens ein Punkt ist innerhalb des Gitters
    return 7 if ($x1 >= $gridx1 && $x1 <= $gridx2 &&
		 $y1 >= $gridy1 && $y1 <= $gridy2);
    return 6 if ($x2 >= $gridx1 && $x2 <= $gridx2 &&
		 $y2 >= $gridy1 && $y2 <= $gridy2);

    # beide Punkte sind außerhalb des Gitters
    return 0 if $x1 < $gridx1 && $x2 < $gridx1;
    return 0 if $x1 > $gridx2 && $x2 > $gridx2;
    return 0 if $y1 < $gridy1 && $y2 < $gridy1;
    return 0 if $y1 > $gridy2 && $y2 > $gridy2;

    my $sgn;
    my $ges_strecke = sqrt(($x1-$x2)*($x1-$x2) + ($y1-$y2)*($y1-$y2));

    if ($x1 != $x2) {
	# Schnittpunkt-Test am rechten Rand
	my $d_x1_gridx1 = ($gridx1 - $x1);
	my $a = $d_x1_gridx1*$ges_strecke/($x2-$x1);
	my $b = sqrt($a*$a - $d_x1_gridx1*$d_x1_gridx1);
	$sgn = ($y1 < $y2 ? 1 : -1);
	$sgn *= -1 if (($x1 < $x2 && $x1 > $gridx1) ||
		       ($x2 < $x1 && $x1 < $gridx1));
	my $schnitt_y_gridx1 = $y1 + $sgn*$b;

	if ($schnitt_y_gridx1 >= $gridy1 &&
	    $schnitt_y_gridx1 <= $gridy2) {
	    warn "Gefunden: $gridy1 <= $schnitt_y_gridx1 <= $gridy2\n" if $VERBOSE;
	    return 1;
	}

	# Schnittpunkt-Test am linken Rand
	my $d_x1_gridx2 = ($gridx2 - $x1);
	$a = $d_x1_gridx2*$ges_strecke/($x2-$x1);
	$b = sqrt($a*$a - $d_x1_gridx2*$d_x1_gridx2);
	$sgn = ($y1 < $y2 ? 1 : -1);
	$sgn *= -1 if (($x1 < $x2 && $x1 > $gridx2) ||
		       ($x2 < $x1 && $x1 < $gridx2));
	my $schnitt_y_gridx2 = $y1 + $sgn*$b;

	if ($schnitt_y_gridx2 >= $gridy1 &&
	    $schnitt_y_gridx2 <= $gridy2) {
	    warn "Gefunden: $gridy1 <= $schnitt_y_gridx2 <= $gridy2\n" if $VERBOSE;
	    return 2;
	}
    }

    if ($y2 != $y1) {
	# Schnittpunkt-Test am oberen Rand (geometrisch unten)
	my $d_y1_gridy2 = ($gridy2 - $y1);
	my $a = $d_y1_gridy2*$ges_strecke/($y2-$y1);
	my $b = sqrt($a*$a - $d_y1_gridy2*$d_y1_gridy2);
	$sgn = ($x1 < $x2 ? 1 : -1);
	$sgn *= -1 if (($y1 < $y2 && $y1 > $gridy2) ||
		       ($y2 < $y1 && $y1 < $gridy2));
	my $schnitt_x_gridy2 = $x1 + $sgn*$b;

	if ($schnitt_x_gridy2 >= $gridx1 &&
	    $schnitt_x_gridy2 <= $gridx2) {
	    warn "Gefunden: $gridx1 <= $schnitt_x_gridy2 <= $gridx2\n" if $VERBOSE;
	    return 4;
	}

	# Schnittpunkt-Test am unteren Rand (geometrisch oben)

	my $d_y1_gridy1 = ($gridy1 - $y1);
	$a = $d_y1_gridy1*$ges_strecke/($y2-$y1);
	$b = sqrt($a*$a - $d_y1_gridy1*$d_y1_gridy1);
	$sgn = ($x1 < $x2 ? 1 : -1);
	$sgn *= -1 if (($y1 < $y2 && $y1 > $gridy1) ||
		       ($y2 < $y1 && $y1 < $gridy1));
	my $schnitt_x_gridy1 = $x1 + $sgn*$b;

	if ($schnitt_x_gridy1 >= $gridx1 &&
	    $schnitt_x_gridy1 <= $gridx2) {
	    warn "Gefunden: $gridx1 <= $schnitt_x_gridy1 <= $gridx2\n" if $VERBOSE;
	    return 3;
	}
    }

    0;
}

# in: point ($px,$py)
#     line ($s0x,$s0y) - ($s1x,$s1y)
# out: minimum distance from point to line
sub distance_point_line {
    my($px,$py,$s0x,$s0y,$s1x,$s1y) = @_;
    my($sxd, $syd) = ($s1x-$s0x, $s1y-$s0y);
    if ($sxd+$syd==0) { # line is really a point
	return sqrt(sqr($px-$s0x)+sqr($py-$s0y));
    }
    my $tf = (($px-$s0x)*($s1x-$s0x) + ($py-$s0y)*($s1y-$s0y)) /
	     ($sxd*$sxd + $syd*$syd);
    # $nx/$ny: nearest point on line
    my $nx = $s0x+$tf*$sxd;
    my $ny = $s0y+$tf*$syd;
    if ((($nx >= $s0x && $nx <= $s1x) || ($nx >= $s1x && $nx <= $s0x))
	&&
	(($ny >= $s0y && $ny <= $s1y) || ($ny >= $s1y && $ny <= $s0y))
       ) {
	my $dx = $s0x-$px+$tf*$sxd;
	my $dy = $s0y-$py+$tf*$syd;
	sqrt($dx*$dx+$dy*$dy);
    } else {
	# nearest point is out of line ... check the endpoints of the line
	my $dist0 = sqrt(sqr($s0x-$px) + sqr($s0y-$py));
	my $dist1 = sqrt(sqr($s1x-$px) + sqr($s1y-$py));
	if ($dist0 < $dist1) {
	    $dist0;
	} else {
	    $dist1;
	}
    }
}

# Return the approximated center of an polygon.
# Coordinates of the polygon are supplied in @koord (flat list of x and y
# values).
#XXX original source?
#XXX this algorithm seems to have problems with certain polygons (just test: Paul-Löbe-Haus from bbbike/data/sehenswuerdigkeit)
sub get_polygon_center {
    my(@koord) = @_;

    # make closed polygon:
    if ($koord[0] != $koord[-2] && $koord[1] != $koord[-1]) {
	push @koord, @koord[0,1];
    }

    my $n = 0;
    my($sumx, $sumy) = (0, 0);
    my $ovfl = 0;
    my $step = 1;
    for(my $inx = 0; $inx < $#koord-2; $inx+=2) {
	my($x1,$y1, $x2,$y2) = (@koord[$inx..$inx+3]);
	my $len = sqrt(sqr($x1-$x2) + sqr($y1-$y2));
	next if $len == 0;
	my($ex,$ey) = ($step*($x2-$x1)/$len,$step*($y2-$y1)/$len);
	my($sx,$sy) = ($x1,$y1);
	if ($ovfl > 0) {
	    my $ovfl_x = $ex/$step*$ovfl;
	    my $ovfl_y = $ey/$step*$ovfl;
	    next if (abs($ovfl_x) > abs($x2-$x1) ||
		     abs($ovfl_y) > abs($y2-$y1));
	    $sx += $ovfl_x;
	    $sy += $ovfl_y;
	}
	my $x_cmp = ($sx < $x2);
	my $y_cmp = ($sy < $y2);
	my $oldn = $n;
	while ((($x_cmp && $sx < $x2) ||
		(!$x_cmp && $sx > $x2)) &&
	       (($y_cmp && $sy < $y2) ||
		(!$y_cmp && $sy > $y2))) {
	    $sumx += $sx;
	    $sumy += $sy;
	    $n++;

	    $sx += $ex;
	    $sy += $ey;
	}

	if ($oldn < $n) {
	    $ovfl = sqrt(sqr($x2-($sx-$ex))+sqr($y2-($sy-$ey)));
	} else {
	    $ovfl -= sqrt(sqr($x2-$sx)+sqr($y2-$sy));
	}
    }
    if ($n != 0) {
	($sumx/$n, $sumy/$n);
    } else {
	undef;
    }
}

# XXX check for enclosed missing
# only for parallel rectangles
sub intersect_rectangles {
    my($ax,$ay,$bx,$by, $cx,$cy,$dx,$dy) = @_;
    # horizontal against vertical
    return 1 if intersect_lines($ax,$ay,$bx,$ay, $cx,$cy,$cx,$dy);
    return 1 if intersect_lines($ax,$ay,$bx,$ay, $dx,$cy,$dx,$dy);
    return 1 if intersect_lines($ax,$by,$bx,$by, $cx,$cy,$cx,$dy);
    return 1 if intersect_lines($ax,$by,$bx,$by, $dx,$cy,$dx,$dy);

    # vertical against horizontal
    return 1 if intersect_lines($ax,$ay,$ax,$by, $cx,$cy,$dx,$cy);
    return 1 if intersect_lines($ax,$ay,$ax,$by, $cx,$dy,$dx,$dy);
    return 1 if intersect_lines($bx,$ay,$bx,$by, $cx,$cy,$dx,$cy);
    return 1 if intersect_lines($bx,$ay,$bx,$by, $cx,$dy,$dx,$dy);

    0;
}


# from mapsearch.c
sub intersect_lines {
    my($ax,$ay,$bx,$by, $cx,$cy,$dx,$dy) = @_;

    my $numerator = (($ay-$cy)*($dx-$cx) - ($ax-$cx)*($dy-$cy));
    my $denominator = (($bx-$ax)*($dy-$cy) - ($by-$ay)*($dx-$cx));

    if (($denominator == 0) && ($numerator == 0)) { # lines are coincident, intersection is a line segement if it exists
	if ($ay == $cy) { # coincident horizontally, check x's
	    if ((($ax >= min($cx,$dx)) && ($ax <= max($cx,$dx))) || (($bx >= min($cx,$dx)) && ($bx <= max($cx,$dx)))) {
		return 1;
	    } else {
		return 0;
	    }
	} else { # test for y's will work fine for remaining cases
	    if ((($ay >= min($cy,$dy)) && ($ay <= max($cy,$dy))) || (($by >= min($cy,$dy)) && ($by <= max($cy,$dy)))) {
		return 1;
	    } else {
		return 0;
	    }
	}
    }

    if ($denominator == 0) { # lines are parallel, can't intersect
	return 0;
    }

    my $r = $numerator/$denominator;

    if (($r<0) || ($r>1)) {
	return 0; # no intersection
    }

    $numerator = (($ay-$cy)*($bx-$ax) - ($ax-$cx)*($by-$ay));
    my $s = $numerator/$denominator;

    if (($s<0) || ($s>1)) {
	return 0; # no intersection
    }

    1;
}

sub point_in_grid {
    my($x1,$y1,$gridx1,$gridy1,$gridx2,$gridy2) = @_;
    return ($x1 >= $gridx1 && $x1 <= $gridx2 &&
	    $y1 >= $gridy1 && $y1 <= $gridy2);
}

# REPO BEGIN
# REPO NAME sqr /home/e/eserte/src/repository 
# REPO MD5 846375a266b4452c6e0513991773b211
sub sqr { $_[0] * $_[0] }
# REPO END

# REPO BEGIN
# REPO NAME min /home/e/eserte/src/repository 
# REPO MD5 80379d2502de0283d7f02ef8b3ab91c2
BEGIN {
    if (eval { require List::Util; 1 }) {
	*min = \&List::Util::min;
    } else {
	*min = sub {
	    my $min = $_[0];
	    foreach (@_[1..$#_]) {
		$min = $_ if $_ < $min;
	    }
	    $min;
	};
    }
}
# REPO END

# REPO BEGIN
# REPO NAME max /home/e/eserte/src/repository 
# REPO MD5 6156c68fa67185196c12f0fde89c0f6b
BEGIN {
    if (eval { require List::Util; 1 }) {
	*max = \&List::Util::max;
    } else {
	*max = sub {
	    my $max = $_[0];
	    foreach (@_[1..$#_]) {
		$max = $_ if $_ > $max;
	    }
	    $max;
	};
    }
}
# REPO END

1;

__END__
