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simgear/simgear/sound/sound.hxx
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// sound.hxx -- Sound class implementation
//
// Started by Erik Hofman, February 2002
//
// Copyright (C) 2002 Erik Hofman - erik@ehofman.com
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License as
// published by the Free Software Foundation; either version 2 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
//
// $Id$
/**
* \file sound.hxx
* Provides a class to manage a single sound event including things
* like looping, volume and pitch changes.
*/
#ifndef _SG_SOUND_HXX
#define _SG_SOUND_HXX 1
#ifndef __cplusplus
# error This library requires C++
#endif
#include <simgear/compiler.h>
#include <simgear/props/condition.hxx>
#include "soundmgr.hxx"
static const double MAX_TRANSIT_TIME = 0.1; // 100 ms.
/**
* Class for handling one sound event.
*
* This class handles everything for a particular sound event, by
* scanning an a pre-loaded property tree structure for sound
* settings, setting up its internal states, and managing sound
* playback whenever such an event happens.
*/
class SGSound
{
public:
SGSound();
virtual ~SGSound();
/**
* Initialize the sound event.
*
* Prior to initialization of the sound event the propgrams property root
* has to be defined, the sound configuration XML tree has to be loaded
* and a sound manager class has to be defined.
*
* A sound configuration file would look like this:
* <fx>
* <event_name>
* <name/> Define the name of the event. For refference only.
* <mode/> Either:
* looped: play this sound looped.
* in-transit: play looped while the event is happening.
* once: play this sound once.
* <path/> The relative path to the audio file.
* <property/> Take action if this property becomes true.
* <condition/> Take action if this condition becomes true.
* <volume> or <pitch> Define volume or pitch settings.
* <property/> Take the value of this property as a refference for the
* result.
* <internal/> Either:
* dt_start: the time elapsed since this sound is playing.
* dt_stop: the time elapsed since this sound has stopped.
* <offset/> Add this value to the result.
* <factor/> Multiply the result by this factor.
* <min/> Make sure the value is never less than this value.
* <max/> Make sure the value is never larger than this value.
* </volume> or </pitch>
* </event_name>
*
* <event_name>
* </event_name>
* </fx>
*
* @param root The root node of the programs property tree.
* @param child A pointer to the location of the current event as defined
* in the configuration file.
* @param sndmgr A pointer to a pre-initialized sound manager class.
* @param path The path where the audio files remain.
*/
virtual void init (SGPropertyNode *, SGPropertyNode *, SGSoundMgr *,
const string &);
/**
* Check wheter an event has happened and if action has to be taken.
*/
virtual void update (double dt);
/**
* Stop taking action on the pre-defined events.
*/
void stop();
protected:
enum { MAXPROP=5 };
enum { ONCE=0, LOOPED, IN_TRANSIT };
enum { LEVEL=0, INVERTED, FLIPFLOP };
// SGSound properties
typedef struct {
SGPropertyNode * prop;
double (*fn)(double);
double *intern;
double factor;
double offset;
double min;
double max;
bool subtract;
} _snd_prop;
private:
SGSoundMgr * _mgr;
SGSimpleSound * _sample;
SGCondition * _condition;
SGPropertyNode * _property;
bool _active;
string _name;
int _mode;
double _prev_value;
double _dt_play;
double _dt_stop;
double _stopping; // time after the sound should have stopped.
// This is usefull for lost packets in in-trasit mode.
vector<_snd_prop> _volume;
vector<_snd_prop> _pitch;
};
#endif // _SG_SOUND_HXX