Been following the tutorial on how to make pong in SDL from the SDL manual. Have run into a few issues and have run into another. In the block that allows for paddle movement I have gotten Errors saying that I have not declared $event. even though It was declared a few lines prior. Just wondering what I am doing wrong. UPDATE......Nevermind I figured it out.

#!/usr/bin/perl
use strict;
use warnings;

# These will allow us to use all the modules necessary to create a GUI
+.
# They are all parts of the Perl SDL module.
# The :: are use to seperate the name of the module and its correspond
+ing member.
use SDL;
use SDL::Events;
use SDLx::App;
use SDLX::Rect;


# First is to set up the screen.
# The => operator is similiar to a comma.
# but it treates the word to the left as a quoted word.
# Even though there isn't any quotes.
my $app = SDLx::App->new(
    width        => 1000,
    height       => 1000,
    title        => 'PONG',
    dt           => 0.02,
    exit_on_quit => 1,
);

# The next step is to set up the paddles for each player.
# This is done in a hash reference.
# This is done so its possible to add information later.
# The numbers may need to be changed later to fit the paddles to the s
+creen.
# I am not 100% sure what -> actually does.
# Other than the fact its a deference operator.
# h is a shortened reference to height
my $player1 = {
    paddle => SDLx::Rect->new( 10, $app->h / 2, 10, 40),
};
my $player2 = {
    paddel => SDLx::Rect->new( $app->w - 20, $app->h / 2, 10, 40)
};

# This is to create the ball
my $ball = {
    rect => SDLx::Rect->new( $app->w / 2, $app->h / 2, 10, 10 ),
};

# This is a show handler.
# This will render the objects to the screen.
$app->add_show_handler (
    sub {
        $app->draw_rect( [ 0, 0, $app->w, $app->h ], 0x000000FF );
        $app->draw_rect( $ball->{rect}, 0xFF0000FF );
        $app->draw_rect( $player1->{paddle}, 0xFF0000FF );
        $app->draw_rect( $player2->{paddle}, 0xFF0000FF );
        $app->update;
      }
    );
# This section will allow the paddles to be moved.
$player1 = {
    paddle => SDLx::Rect->new( 10, $app->h / 2, 10, 40 ),
    v_y => 0,
};
$app->add_move_handler( sub {
    my ( $step, $app ) = @_;
    my $paddle = $player1->{paddle};
    my $v_y = $player1->{v_y};
    $paddle->( $paddle->y($v_y * $step ));
    $player2 = {
        paddle => SDLx::Rect->new( $app->w - 20, $app->h / 2, 10, 40),
        v_y => 0,
    };
$app->add_move_handler( sub {
    my ( $step, $app ) = @_;
    my $paddle = $player2->{paddle};
    my $v_y = $player2->{v_y};

    $paddle->y( $paddle->y ( $v_y * $step ) );
});
$app->add_event_handler(
    sub {
        my ( $event, $app ) = @_;
        if ( $event->type == SDL_KEYDOWN ) {
            if ( $event->key_sym == SDLK_UP) {
                $player1->{v_y} = -2;
            }
            $player1->{v_y} = 2;
        }
    }
    elsif ( $event->type == SDL_KEYUP) {
        if (
            $event->key_sym == SDLK_UP
            or $event->key_sym == SDLK_DOWN
        ) {
            $player1->{v_y} = 0;
        }
    }
);

$app->run;
[download]

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.