Difference between revisions of "Development/Tutorials/Games/KALEngine"

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In this example, we will play a "Hello Word". We don't need to specify any sound file, openAL provides a default sound itself.
 
In this example, we will play a "Hello Word". We don't need to specify any sound file, openAL provides a default sound itself.
  
<code cppqt>
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<syntaxhighlight lang="cpp-qt">
  
 
#include <KALEngine>
 
#include <KALEngine>
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- First, we initialize the sound engine. The init() function can optionally takes one argument, the device name. You can retrieve the list of devices, using this static function :
 
- First, we initialize the sound engine. The init() function can optionally takes one argument, the device name. You can retrieve the list of devices, using this static function :
  
<code cppqt>
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<syntaxhighlight lang="cpp-qt">
 
QStringList devicesList().
 
QStringList devicesList().
 
</code>
 
</code>
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If you want to try playing something else than the default "Hello World", you can download this short simple : [[http://ktank.free.fr/kalengine/ocean.wav ocean.wav]] and replace the sound object definition by:
 
If you want to try playing something else than the default "Hello World", you can download this short simple : [[http://ktank.free.fr/kalengine/ocean.wav ocean.wav]] and replace the sound object definition by:
  
<code cppqt>
+
<syntaxhighlight lang="cpp-qt">
 
     KALSource *sound = new KALSource("ocean.wav");
 
     KALSource *sound = new KALSource("ocean.wav");
 
</code >
 
</code >

Revision as of 21:28, 29 June 2011

KALEngine tutorial
Tutorial Series   KALEngine developement
Prerequisites   None
What's Next   Nothing at the moment
Further Reading   KGLEngine2d's code

Abstract

Phonon is not really designed to handle multiple sounds at the same time. KALEngine is made for games and create one thread per sound, using the openAL library. You also get all the other openAL goodness like 3D sounds, effects and multichannel.

Installation

1: You need to have the following libraries installed.

  • openAL (sound api)
  • alut (openAL toolkit)
  • libSndFile (load sound file).

If you're using a Debian-based distribution, you can install them that way :

sudo apt-get install libalut0-dev libopenal1-dev libsndfile1-dev libvorbis-dev libvorbisfile libogg-dev

2: Build and install KALEngine from svn : svn co svn://anonsvn.kde.org/home/kde/trunk/playground/games/KALEngine/

  • cmake -DCMAKE_INSTALL_PREFIX=$(kde-config --prefix)
  • make
  • sudo make install

Hello Word

In this example, we will play a "Hello Word". We don't need to specify any sound file, openAL provides a default sound itself.

#include <KALEngine>
#include <KALSource>
#include <KDebug>
 
int main(int argc, char **argv)
{
    // create an OpenAL object
    KALEngine soundEngine;
    // initialize OpenAL context and device
    soundEngine.init(); 
 
    // create a sound, since we haven't specified any filename in the constructor, it will play the "Hello World"
    KALSource *sound = new KALSource();
 
    // play the sound
    sound->play();
 
    // print the elapsed time until the sound has finished playing
    while (sound->status() == AL_PLAYING)
    {
        kDebug() << sound->elapsedTime();
    }
 
    // clear the buffer
    delete sound;
    // ...and close the device
    soundEngine.shutdown();
 
    return 0;
}
 
 
</code>
 
- First, we initialize the sound engine. The init() function can optionally takes one argument, the device name. You can retrieve the list of devices, using this static function :
 
<syntaxhighlight lang="cpp-qt">
QStringList devicesList().
</code>
 
- Then, we create a KALsource. KALSource can be used for playing small sounds(shoot, scream, tic, walk, etc). It will load the entire file inside a buffer, so be careful if you try to play a big file using it.
 
If you want to try playing something else than the default "Hello World", you can download this short simple : [[http://ktank.free.fr/kalengine/ocean.wav ocean.wav]] and replace the sound object definition by:
 
<syntaxhighlight lang="cpp-qt">
    KALSource *sound = new KALSource("ocean.wav");
</code >
 
You can only use it to play wav file at the moment, but we hope to bring ogg support soon.
For playing music, please wait until KALStream tutorial is up.
 
- The sound can now be played by simply calling <b>play()</b>. This function is asynchronous, meaning your program doesn't have to wait until the sound has finished playing to continue.
 
- Then, to know when the sound has ended, we create a loop using <b>status()</b> which returns ever <b>AL_PLAYING</b> or <b>AL_STOPED</b>.
 
- Inside the loop, we print the time since the sound started playing using <b>elapsedTime()</b>. It returns an ALfloat with the elapsed time expressed in seconds.
 
- Finally, we have to clear the KALSource buffer by deleting the KALSource pointer and close the device by calling <b>shutdown()</b>.
 
== Multi-channel ==
 
sound1->play();
sound2->play();
 
...to develop
== 3d sound ==
 
KALSource->setPosition(x,y,z)
...to develop
 
 
{{tip|For more information on how OpenAL works, see the documentation [[http://connect.creativelabs.com/openal/Documentation/OpenAL_Programmers_Guide.pdf OpenAL programmers Guide ]]}}
 
{{TODO|Create KALStream}}

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