#!/usr/bin/perl

# fix Cerium xml normal vector

my $i = -1;
my (@x,@y,@z);
my @cord;
my $flag = 0;
my $fix = 1;

sub v {
    print "$x[0] $y[0] $z[0]\n";
    print "$x[1] $y[1] $z[1]\n";
    print "$x[2] $y[2] $z[2]\n";
}

sub outer {
    my ($ax,$ay,$az) = (
	$x[1]-$x[0],
	$y[1]-$y[0],
	$z[1]-$z[0],
	);
    my ($bx,$by,$bz) = (
	$x[2]-$x[0],
	$y[2]-$y[0],
	$z[2]-$z[0],
	);
    my ($ox,$oy,$oz) = (
	$ay*$bz - $az*$by,
        -$ax*$bz + $az*$bx,
	$ax*$by - $ay*$bx,
	);
    my($r) = sqrt($ox*$ox+$oy*$oy+$oz*$oz);
    ($ox,$oy,$oz) = ($ox/$r,$oy/$r,$oz/$r);
    push(@cord, [$ox,$oy,$oz]);
    # print "    $ox   $oy   $oz\n";
}

if (@ARGV != 2) {
    die "Usage : objectname filename\n";
}

my ($object, $file) = @ARGV;
open(IN, $file);

while(<IN>) {
    if (! $fix) {
	if (/<sur/) {
	    print;
	    next;    
	}
    }
    if (/<normal/) {
	$i= -2;
	print if ($fix);
	next;
    }
    if (/<\/normal/) {
	$i = -1;
	print if ($fix);
	next;
    }

    if (/$object/) {
	$flag = 1;
    }

    if (/\/$object/) {
	$flag = 0;
    }

    if ( $i < -1) {
	if ($i== -4) {
	    my $cord = shift(@cord);
	    if ($fix) {

		if ($flag == 1) {
		    $cord->[0] = -$cord->[0];
		    $cord->[1] = -$cord->[1];
		    $cord->[2] = -$cord->[2];
		}

		print "  $cord->[0]  $cord->[1]  $cord->[2]  \n";
		print "  $cord->[0]  $cord->[1]  $cord->[2]  \n";
		print "  $cord->[0]  $cord->[1]  $cord->[2]  \n";

	    } else {
		print "outer $i   $cord->[0]  $cord->[1]  $cord->[2]  \n";
		print ;
	    }
	    $i = -2;
	} else {
	    $i--;
	}
	next;
    }
    print if ($fix);
    if (/<\/coord/) {
	$i = -1;
	next;
    }
    if (/<coord/) {
	@cord = ();
	$i=0;
	next;
    } 
    if ($i<0) {
	next; 
    }
    if (/([-]*[.\d]+)\s+([-]*[.\d]+)\s+([-]*[.\d]+)/) {
	($x[$i],$y[$i],$z[$i]) = ($1,$2,$3);
#       print "$i $_";
        if ($i==2) {
	    &outer;
	    $i = 0;
	    next;
        }
        $i++;     
    } else {
	$i = -1;
    }
}

# end