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Merge pull request #474 from trwyant/68_Orbit_perl_trw
Port 68_Orbit to Perl.
This commit is contained in:
Jeff Atwood
@@ -1,3 +1,11 @@
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Original source downloaded [from Vintage Basic](http://www.vintage-basic.net/games.html)
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Conversion to [Perl](https://www.perl.org/)
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This Perl script is a port of orbit, which is the 68th entry in Basic
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Computer Games.
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In this game you are a planetary defense gunner trying to shoot down a
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cloaked Romulan ship before it can escape.
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This is pretty much a straight port of the BASIC into idiomatic Perl.
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239
68_Orbit/perl/orbit.pl
Executable file
239
68_Orbit/perl/orbit.pl
Executable file
@@ -0,0 +1,239 @@
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#!/usr/bin/env perl
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use 5.010; # To get 'state' and 'say'
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use strict; # Require explicit declaration of variables
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use warnings; # Enable optional compiler warnings
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use English; # Use more friendly names for Perl's magic variables
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use Term::ReadLine; # Prompt and return user input
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our $VERSION = '0.000_01';
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use constant PI => atan2( 0, -1 );
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use constant DEG_TO_RAD => atan2( 0, -1 ) / 180;
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print <<'EOD';
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ORBIT
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Creative Computing Morristown, New Jersey
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Somewhere above your planet is a Romulan ship.
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The ship is in a constant polar orbit. Its
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distance from the center of your planet is from
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10,000 to 30,000 miles and at its present velocity can
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circle your planet once every 12 to 36 hours.
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Unfortunately, they are using a cloaking device so
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you are unable to see them, but with a special
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instrument you can tell how near their ship your
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photon bomb exploded. You have seven hours until they
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have built up sufficient power in order to escape
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your planet's gravity.
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Your planet has enough power to fire one bomb an hour.
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At the beginning of each hour you will be asked to give an
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angle (between 0 and 360) and a distance in units of
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100 miles (between 100 and 300), after which your bomb's
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distance from the enemy ship will be given.
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An explosion within 5,000 miles of the Romulan ship
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will destroy it.
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Below is a diagram to help you visualize your plight.
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90
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0000000000000
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0000000000000000000
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000000 000000
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00000 00000
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00000 XXXXXXXXXXX 00000
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00000 XXXXXXXXXXXXX 00000
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0000 XXXXXXXXXXXXXXX 0000
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0000 XXXXXXXXXXXXXXXXX 0000
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0000 XXXXXXXXXXXXXXXXXXX 0000
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180<== 00000 XXXXXXXXXXXXXXXXXXX 00000 ==>0
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0000 XXXXXXXXXXXXXXXXXXX 0000
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0000 XXXXXXXXXXXXXXXXX 0000
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0000 XXXXXXXXXXXXXXX 0000
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00000 XXXXXXXXXXXXX 00000
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00000 XXXXXXXXXXX 00000
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00000 00000
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000000 000000
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0000000000000000000
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0000000000000
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270
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X - Your planet
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O - The orbit of the Romulan ship
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On the above diagram, the Romulan ship is circling
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counterclockwise around your planet. Don't forget that
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without sufficient power the Romulan ship's altitude
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and orbital rate will remain constant.
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Good luck. The Federation is counting on you.
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EOD
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while ( 1 ) { # Iterate indefinitely
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my $romulan_angle = int( 360 * rand() );
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my $romulan_distance = int( 200 * rand() + 200 );
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my $romulan_velocity = int( 20 * rand() + 10 );
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my $hour = 0;
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while ( 1 ) { # Iterate indefinitely
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$hour++;
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print <<"EOD";
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This is hour $hour, at what angle do you wish to send
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EOD
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my $bomb_angle = get_input(
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'do you wish to send your photon bomb? ',
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sub { m/ \A [0-9]+ \z /smx },
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"Please enter an integer angle in degrees\n",
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);
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say '';
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my $bomb_distance = get_input(
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'How far out do you wish to detonate it? ',
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sub { m/ \A [0-9]+ \z /smx },
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"Please enter an integer distance in hundreds of miles\n",
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);
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$romulan_angle = ( $romulan_angle + $romulan_velocity ) % 360;
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my $miss_angle = abs( $romulan_angle - $bomb_angle );
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$miss_angle = 360 - $miss_angle if $miss_angle >= 180;
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my $miss_distance = int sqrt(
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$romulan_distance * $romulan_distance +
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$bomb_distance * $bomb_distance -
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2 * $romulan_distance * $bomb_distance *
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cos( $miss_angle * DEG_TO_RAD ) );
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print <<"EOD";
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Your photon bomb exploded $miss_distance*10^2 miles from the
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Romulan ship.
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EOD
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if ( $miss_distance <= 50 ) {
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say "\nYou have successfully completed your mission.";
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last;
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} elsif ( $hour > 6 ) {
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say "\nYou have allowed the Romulans to escape.";
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last;
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}
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}
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say "\nAnother Romulan ship has gone into orbit.";
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last unless get_yes_no( 'Do you wish to try to destroy it' );
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}
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print <<'EOD';
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Good bye.
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EOD
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# Get input from the user. The arguments are:
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# * The prompt
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# * A reference to validation code. This code receives the response in
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# $ARG and returns true for a valid response.
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# * A warning to print if the response is not valid. This must end in a
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# return.
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# The first valid response is returned. An end-of-file terminates the
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# script.
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sub get_input {
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my ( $prompt, $validate, $warning ) = @ARG;
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# If no validator is passed, default to one that always returns
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# true.
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$validate ||= sub { 1 };
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# Create the readline object. The 'state' causes the variable to be
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# initialized only once, no matter how many times this subroutine is
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# called. The do { ... } is a compound statement used because we
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# need to tweak the created object before we store it.
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state $term = do {
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my $obj = Term::ReadLine->new( 'reverse' );
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$obj->ornaments( 0 );
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$obj;
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};
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while ( 1 ) { # Iterate indefinitely
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# Read the input into the topic variable, localized to prevent
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# Spooky Action at a Distance. We exit on undef, which signals
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# end-of-file.
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exit unless defined( local $ARG = $term->readline( $prompt ) );
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# Return the input if it is valid.
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return $ARG if $validate->();
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# Issue the warning, and go around the merry-go-round again.
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warn $warning;
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}
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}
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# Get a yes-or-no answer. The argument is the prompt, which will have
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# '? [y/n]: ' appended. The donkey work is done by get_input(), which is
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# requested to validate the response as beginning with 'y' or 'n',
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# case-insensitive. The return is a true value for 'y' and a false value
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# for 'n'.
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sub get_yes_no {
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my ( $prompt ) = @ARG;
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state $map_answer = {
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n => 0,
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y => 1,
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};
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my $resp = lc get_input(
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"$prompt? [y/n]: ",
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sub { m/ \A [yn] /smxi },
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"Please respond 'y' or 'n'\n",
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);
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return $map_answer->{ substr $resp, 0, 1 };
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}
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__END__
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=head1 TITLE
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orbit - Play the game 'Orbit' from Basic Computer Games
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=head1 SYNOPSIS
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orbit.pl
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=head1 DETAILS
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This Perl script is a port of orbit, which is the 68th entry in Basic
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Computer Games.
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In this game you are a planetary defense gunner trying to shoot down a
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cloaked Romulan ship before it can escape.
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This is pretty much a straight port of the BASIC into idiomatic Perl.
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=head1 PORTED BY
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Thomas R. Wyant, III F<wyant at cpan dot org>
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=head1 COPYRIGHT AND LICENSE
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Copyright (C) 2022 by Thomas R. Wyant, III
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This program is free software; you can redistribute it and/or modify it
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under the same terms as Perl 5.10.0. For more details, see the Artistic
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License 1.0 at
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L<https://www.perlfoundation.org/artistic-license-10.html>, and/or the
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Gnu GPL at L<http://www.gnu.org/licenses/old-licenses/gpl-1.0.txt>.
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This program is distributed in the hope that it will be useful, but
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without any warranty; without even the implied warranty of
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merchantability or fitness for a particular purpose.
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=cut
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# ex: set expandtab tabstop=4 textwidth=72 :
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