SFXParameter Class Reference
[Sound]

A sound channel value that can be bound to multiple sound sources. More...

Inheritance diagram for SFXParameter:

Public Member Functions
String	getParameterName ()
	Get the name of the parameter.
void	reset ()
	Reset the parameter's value to its default.
Callbacks

void	onUpdate ()
	Called when the sound system triggers an update on the parameter.
Public Attributes
Sound

SFXChannel	channel
	Channel that the parameter controls.
float	defaultValue
	Value to which the parameter is initially set.
string	description
	Textual description of the parameter.
Point2F	range
	Permitted range for value.
float	value
	Current value of the audio parameter.

Detailed Description

A sound channel value that can be bound to multiple sound sources.

Parameters are special objects that isolate a specific property that sound sources can have and allows to bind this isolated instance to multiple sound sources such that when the value of the parameter changes, all sources bound to the parameter will have their respective property changed.

Parameters are identified and referenced by their internalName. This means that the SFXDescription::parameters and SFXTrack::parameters fields should contain the internalNames of the SFXParameter objects which should be attached to the SFXSources when they are created. No two SFXParameters should have the same internalName.

All SFXParameter instances are automatically made children of the SFXParameterGroup.

Note:: To simply control the volume and/or pitch levels of a group of sounds, it is easier and more efficient to use a sound source group rather than SFXParameters (see Source Hierarchies). Simply create a SFXSource object representing the group, assign SFXDescription::sourceGroup of the sounds appropriately, and then set the volume and/or pitch level of the group to modulate the respective properties of all children.

Parameter Updates

Parameters are periodically allowed to update their own values. This makes it possible to attach custom logic to a parameter and have individual parameters synchronize their values autonomously. Use the onUpdate() callback to attach script code to a parameter update.

Example:

new SFXParameter( EngineRPMLevel )
{
   // Set the name by which this parameter is identified.
   internalName = "EngineRPMLevel";

   // Let this parameter control the pitch of attached sources to simulate engine RPM ramping up and down.
   channel = "Pitch";

   // Start out with unmodified pitch.
   defaultValue = 1;

   // Add a texture description of what this parameter does.
   description = "Engine RPM Level";
};

// Create a description that automatically attaches the engine RPM parameter.
singleton SFXDescription( EngineRPMSound : AudioLoop2D )
{
   parameters[ 0 ] = "EngineRPMLevel";
};

// Create sound sources for the engine.
sfxCreateSource( EngineRPMSound, "art/sound/engine/enginePrimary" );
sfxCreateSource( EngineRPMSound, "art/sound/engine/engineSecondary" );

// Setting the parameter value will now affect the pitch level of both sound sources.
EngineRPMLevel.value = 0.5;
EngineRPMLevel.value = 1.5;