source: proiecte/pmake3d/make3d_original/Make3dSingleImageStanford_version0.1/third_party/vrippack-0.31/src/plytools/ply2bboxcube @ 37

#!/usr/bin/perl
#
# plybbox2cube:
#    This script takes the output of plybbox and generates a
# ply file with the actual faces of a cube for the bounding
# box.
#
# usage:
#   (see below)

sub printUsage {
    print STDERR "\n";
    print STDERR "Usage: ply2bboxcube in1.ply [in2.ply] ...\n";
    print STDERR "\n";
    print STDERR "And it will generate files called in1.bboxcube.ply,\n";
    print STDERR "in2.bboxcube.ply, etc.....\n";
    print STDERR "Which contain all 12 faces of the bounding box.\n";
    print STDERR "\n";
    exit -1;
}

if ($#ARGV == -1 || substr($ARGV[0], 0, 1) eq "-") {
    &printUsage();

} else {
    for ($i = 0; $i <= $#ARGV; $i++) {
        $inname = $ARGV[$i];
        # Check to make sure it ends in .ply
        if (substr($inname, -4, 4) ne ".ply") {
            print STDERR "Err, $inname does not end in .ply, skipping...\n";
            next;
        }
        # open the input file
        if (!open(IN, $inname)) {
            print STDERR "Err, cannot open input ply file $inname, ".
                "skipping....\n";
            next;
        }
        #compute output file, make sure we're not overwriting input
        $outname = $inname;
        $outname =~ s/.ply/.bboxcube.ply/g;
        if ($outname eq $inname) {
            print STDERR "Assertion failure. $outname == $inname? skipping.\n";
            next;
        }
        
        # open output file
        if (!open(OUT, ">$outname")) {
            print STDERR "Err, annot open output ply file $outname, ".
                "skipping....\n";
            next;
        }

        # Run it
        close(IN);
        ($minx, $miny, $minz, $maxx, $maxy, $maxz) = 
            split(' ', `plybbox $inname`);
        &plybboxcreatecube($inname, OUT);
        close(OUT);
    }
}

sub plybboxcreatecube {
    # Assume that these variables have been defined:
    # $minx, $miny, $minz
    # $maxx, $maxy, $maxz

    #
    #       3-----------1
    #      /|          /|    Z
    #     5-----------7 |    |
    #     | |         | |    |  Y
    #     | 6---------|-4    | /
    #     |/          |/     |/
    #     0-----------2      --------X
    #

    print OUT 
"ply
format ascii 1.0
element vertex 8
property float x
property float y
property float z
element face 12
property list uchar int vertex_indices
end_header
$minx $miny $minz
$maxx $maxy $maxz
$maxx $miny $minz
$minx $maxy $maxz
$maxx $maxy $minz
$minx $miny $maxz
$minx $maxy $minz
$maxx $miny $maxz
3 0 2 5
3 5 2 7
3 2 4 7
3 7 4 1
3 4 6 1
3 1 6 3
3 6 0 5
3 6 5 3
3 5 7 3
3 3 7 1
3 6 4 2
3 6 2 0
";
}