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Background

Simple DirectMedia Layer (a.k.a libsdl) is a cross-platform C library that provides access to several input and output devices. Most popularly it is used for its access to the 2D video framebuffer and inputs for games.

In addition to the core library there are several other libraries that provide many features such as Text, Mixers, Images and GFX.

SDL Perl binds several of these libraries as closely as possible in the SDL::* namespace. Moreover SDL Perl provides several high level libraries in the SDLx::* namespace.

The SDLx:: layer

The main purpose of the SDLx::* layer is to smooth out the drudgery from the SDL::* layer. For example drawing a rectangle involves the following work.

NOTE:

Don't worry about understanding the code at this moment. Just compare the two code lisitings below.

use SDL;
use SDL::Video;
use SDL::Surface;
use SDL::Rect;

# the size of the window box or the screen resolution if fullscreen
my $screen_width   = 800;
my $screen_height  = 600;

SDL::init(SDL_INIT_VIDEO);

# setting video mode
my $screen_surface = SDL::Video::set_video_mode($screen_width, 
                                                        $screen_height, 
                                                        32, 
                                                        SDL_ANYFORMAT);

# drawing a rectangle with the blue color
my $mapped_color   = SDL::Video::map_RGB($screen_surface->format(), 0, 0, 255);
SDL::Video::fill_rect($screen_surface,
                      SDL::Rect->new($screen_width / 4, $screen_height / 4,
                                     $screen_width / 2, $screen_height / 2), 
                              $mapped_color);

# update an area on the screen so its visible
SDL::Video::update_rect($screen_surface, 0, 0, $screen_width, $screen_height);

sleep(5); # just to have time to see it

SDL::quit();

While drawing a blue rectangle in the SDLx::* layer is as simple as:

use strict;
use warnings;

use SDL;
use SDLx::App;

my $app = SDLx::App->new( width=> 800, height => 600 );

$app->draw_rect([ $app->width/4, $app->height / 4, $app->width /2, $app->height / 2 ], [0,0,255,255] );

$app->update();

sleep(5);

A secondary purpose of the SDLx::* is to add addtional features for users, such as Layers, Game Loop handling and more.

Audience

This book is written for new users of SDL Perl who have some experience with Perl, but not much experience with SDL. It is not necessary for the audience to be aware of SDL internals, as this book covers most areas as it goes.

Format of this book

This book will be formated into chapters that progressively increase in complexity. However each chapter can be treated as a separate tutorial to jump to and learn.

Each chapter will have a specific task (e.g. Making Pong), which we will work towards. The source for each chapter will be broken up and explained. Sources and data files will be provided on http://sdl.perl.org.

Finally the chapters will end with an exercise the reader can try out.

Purpose of this book

This book is intended to introduce game development to Perl programmers and at the same time introduce Modern Perl through game development. The book will aim to provide simple to intermediate examples and provide suggestions for more advanced endeavours.

Installing SDL Perl

Depending on your platform you may need some dependencies. Then we can do a final CPAN install.

Windows

Alien::SDL will install binaries for 32bit and 64bit so there is no need to compile anything.

MacOSX

Packages

Fink has packages for SDL Perl available. However Pango is not currently supported.

Or Compiling Dependencies

Alien::SDL will compile SDL dependencies from scratch with no problems as long some prerequisites are installed. libfreetype6, libX11, libvorbis, libogg and libpng headers will suffice for most examples in this book.

Linux

Packages

You can use your package maintainers packages:

sudo apt-get install libsdl-net1.2-dev libsdl-mixer1.2-dev \
libsdl1.2-dev libsdl-image1.2-dev libsdl-ttf2.0-dev \ 
libsdl-gfx1.2-dev libsdl-pango-dev

Or Compiling Dependencies

To compile from scratch some Header Packages are required.

sudo apt-get install build-essential xorg-dev libx11-dev \
libpango1.0-dev libfreetype6-dev libvorbis-dev libpng12-dev \
libogg-dev

CPAN install

sudo cpan SDL

For most platforms a CPAN install will suffice. Supported and tested platforms are displayed at http://pass.cpantesters.org/distro/S/SDL.html.

Contact

Hopefully this book shows you areas where SDL Perl can be improved, or you may need help with some issues. Please contact us with one of the following methods:

Internet

SDL Perl's homepage is at http://sdl.perl.org/.

IRC

The channel #sdl on irc.perl.org is very active and a great resource for help and getting involved.

Mailing lists

If you need help with SDL Perl, send an to sdl-devel@perl.org.

Examples

The code examples in this books are provided on http://github.com/PerlGameDev/SDL_Manual/tree/master/code_listings/ .

Acknowledgements

Perl community on #sdl and #perl.

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