Castle Game Engine: CastleSoundEngine: Class TSoundEngine

# Class TSoundEngine
Description | Hierarchy | Fields | Methods | Properties
## Unit CastleSoundEngine ## Declaration `type TSoundEngine = class(TSoundAllocator)` ## Description OpenAL sound engine. Takes care of all the 3D sound stuff, wrapping OpenAL is a nice and comfortable interface. There should always be only one instance of this class, in global SoundEngine variable. See docs at SoundEngine for more details. You can explicitly initialize OpenAL context by ALContextOpen, and explicitly close it by ALContextClose. If you did not call ALContextOpen explicitly (that is, ALInitialized is `False`), then the first LoadBuffer or TRepoSoundEngine.Sound or TRepoSoundEngine.Sound3D will automatically do it for you. If you do not call ALContextClose explicitly, then at destructor we'll do it automatically. ## Hierarchy TObject TSoundAllocator TSoundEngine ## Overview ### Fields
| `internal const DefaultVolume = 1.0;`
| `internal const DefaultDefaultRolloffFactor = 1.0;`
| `internal const DefaultDefaultReferenceDistance = 1.0;`
| `internal const DefaultDefaultMaxDistance = MaxSingle;`
| `internal const DefaultDistanceModel = dmLinearDistanceClamped;`
### Methods
| `constructor Create;`
| `destructor Destroy; override;`
| `procedure ALContextOpen; override;`
| `procedure ALContextClose; override;`
| `function GetContextString(Enum: TALCenum): string;`
| `function LoadBuffer(const URL: string; out Duration: TFloatTime): TSoundBuffer;`
| `function LoadBuffer(const URL: string): TSoundBuffer;`
| `procedure FreeBuffer(var Buffer: TSoundBuffer);`
| `function PlaySound(const Buffer: TSoundBuffer; const Spatial, Looping: boolean; const Importance: Cardinal; const Gain, MinGain, MaxGain: Single; const Position: TVector3Single; const Pitch: Single = 1): TSound;`
| `function PlaySound(const Buffer: TSoundBuffer; const Spatial, Looping: boolean; const Importance: Cardinal; const Gain, MinGain, MaxGain: Single; const Position: TVector3Single; const Pitch: Single; const ReferenceDistance: Single; const MaxDistance: Single): TSound;`
| `procedure ParseParameters;`
| `function ParseParametersHelp: string;`
| `procedure UpdateListener(const Position, Direction, Up: TVector3Single);`
| `function Devices: TSoundDeviceList;`
| `function DeviceNiceName: string;`
### Properties
| `property ALActive: boolean read FALActive;`
| `property ALInitialized: boolean read FALInitialized;`
| `property EFXSupported: boolean read FEFXSupported;`
| `property SoundInitializationReport: string read FSoundInitializationReport;`
| `property OnOpenClose: TNotifyEventList read FOnOpenClose;`
| `property EnableSaveToConfig: boolean read FEnableSaveToConfig write FEnableSaveToConfig default true;`
| `property Volume: Single read FVolume write SetVolume default DefaultVolume;`
| `property Device: string read FDevice write SetDevice;`
| `property Enable: boolean read FEnable write SetEnable default true;`
| `property DefaultRolloffFactor: Single read FDefaultRolloffFactor write FDefaultRolloffFactor default DefaultDefaultRolloffFactor;`
| `property DefaultReferenceDistance: Single read FDefaultReferenceDistance write FDefaultReferenceDistance default DefaultDefaultReferenceDistance;`
| `property DefaultMaxDistance: Single read FDefaultMaxDistance write FDefaultMaxDistance default DefaultDefaultMaxDistance;`
| `property DistanceModel: TSoundDistanceModel read FDistanceModel write SetDistanceModel default DefaultDistanceModel;`
## Description ### Fields
| `internal const DefaultVolume = 1.0;`
| `internal const DefaultDefaultRolloffFactor = 1.0;`
| `internal const DefaultDefaultReferenceDistance = 1.0;`
| `internal const DefaultDefaultMaxDistance = MaxSingle;`
| `internal const DefaultDistanceModel = dmLinearDistanceClamped;`
### Methods
| `constructor Create;`
| `destructor Destroy; override;`
| `procedure ALContextOpen; override;`
Initialize OpenAL library, and output device and context. Sets ALInitialized, ALActive, SoundInitializationReport, EFXSupported, ALMajorVersion, ALMinorVersion. You can set Device before calling this. Note that we continue (without any exception) if the initialization failed for any reason (maybe OpenAL library is not available, or no sound output device is available). You can check things like ALActive and SoundInitializationReport, but generally this class will hide from you the fact that sound is not initialized.
| `procedure ALContextClose; override;`
Release OpenAL context and resources. ALInitialized and ALActive are set to `False`. It's allowed and harmless to cal this when one of them is already `False`.
| `function GetContextString(Enum: TALCenum): string;`
Wrapper for alcGetString.
| `function LoadBuffer(const URL: string; out Duration: TFloatTime): TSoundBuffer;`
Load a sound file into OpenAL buffer. Result is 0 only if we don't have a valid OpenAL context. Note that this method will automatically call ALContextOpen if it wasn't called yet. So result = zero means that ALContextOpen was called, but for some reason failed. The buffer should be released by FreeBuffer later when it's not needed. Although we will take care to always free remaining buffers before closing OpenAL context anyway. (And OpenAL would also free the buffer anyway at closing, although some OpenAL versions could write a warning about this.) We have a cache of sound files here. An absolute URL will be recorded as being loaded to given buffer. Loading the same URL second time returns the same OpenAL buffer. The buffer is released only once you call FreeBuffer as many times as you called LoadBuffer for it.
| `function LoadBuffer(const URL: string): TSoundBuffer;`
| `procedure FreeBuffer(var Buffer: TSoundBuffer);`
Free a sound file buffer. Ignored when buffer is zero. Buffer is always set to zero after this. ###### Exceptions raised ESoundBufferNotLoaded When invalid (not zero, and not returned by LoadBuffer) buffer identifier is given.
| `function PlaySound(const Buffer: TSoundBuffer; const Spatial, Looping: boolean; const Importance: Cardinal; const Gain, MinGain, MaxGain: Single; const Position: TVector3Single; const Pitch: Single = 1): TSound;`
Play a sound from given buffer. We use a smart OpenAL sound allocator, so the sound will be actually played only if resources allow. Use higher Importance to indicate sounds that are more important to play. We set the sound properties and start playing it. Both spatialized (3D) and not sounds are possible. When Spatial = `False`, then Position is ignored (you can pass anything, like ZeroVector3Single). ###### Returns The allocated sound as TSound. Returns `Nil` when there were no resources to play another sound (and it wasn't important enough to override another sound). Always returns `Nil` when SoundBuffer is zero (indicating that buffer was not loaded). In simple cases you can just ignore the result of this method. In advanced cases, you can use it to observe and update the sound later.
| `function PlaySound(const Buffer: TSoundBuffer; const Spatial, Looping: boolean; const Importance: Cardinal; const Gain, MinGain, MaxGain: Single; const Position: TVector3Single; const Pitch: Single; const ReferenceDistance: Single; const MaxDistance: Single): TSound;`
| `procedure ParseParameters;`
Parse parameters in Parameters and interprets and removes recognized options. Internally it uses Parameters.Parse with ParseOnlyKnownLongOptions = `True`. Recognized options: --audio-device DEVICE-NAME Set Device variable to given argument. --no-sound Disable any sound (sets Enable to `False`). More user-oriented documentation for the above options is here: [http://castle-engine.sourceforge.net/openal_notes.php#section_options]
| `function ParseParametersHelp: string;`
Help string for options parsed by ParseParameters. Note that it also lists the available OpenAL Devices, as they are valid arguments for the --audio-device option.
| `procedure UpdateListener(const Position, Direction, Up: TVector3Single);`
Set OpenAL listener position and orientation.
| `function Devices: TSoundDeviceList;`
List of available OpenAL sound devices. Read-only. Use `Devices[].Name` as Device values. On some OpenAL implementations, some other Device values may be possible, e.g. old Loki implementation allowed some hints to be encoded in Lisp-like language inside the Device string.
| `function DeviceNiceName: string;`
### Properties
| `property ALActive: boolean read FALActive;`
Do we have active OpenAL context. This is `True` when you successfully called ALContextOpen (and you didn't call ALContextClose yet). This also implies that OpenAL library is loaded, that is ALInited = `True`.
| `property ALInitialized: boolean read FALInitialized;`
Did we attempt to initialize OpenAL context. This indicates that ALContextOpen was called, and not closed with ALContextClose yet. Contrary to ALActive, this doesn't care if ALContextOpen was a success.
| `property EFXSupported: boolean read FEFXSupported;`
Are OpenAL effects (EFX) extensions supported. Meaningful only when ALActive, that is it's initialized by ALContextOpen.
| `property SoundInitializationReport: string read FSoundInitializationReport;`
| `property OnOpenClose: TNotifyEventList read FOnOpenClose;`
Events fired after OpenAL context and device are being open or closed. More precisely, when ALInitialized changes (and so, possibly, ALActive changed).
| `property EnableSaveToConfig: boolean read FEnableSaveToConfig write FEnableSaveToConfig default true;`
Should we save Enable to config file in SaveToConfig call. This is always reset to `True` after setting Enable value.
| `property Volume: Single read FVolume write SetVolume default DefaultVolume;`
Sound volume, affects all OpenAL sounds (effects and music). This must always be within 0..1 range. 0.0 means that there are no effects (this case should be optimized).
| `property Device: string read FDevice write SetDevice;`
Sound output device, used when initializing OpenAL context. You can change it even when OpenAL is already initialized. Then we'll close the old device (ALContextClose), change Device value, and initialize context again (ALContextOpen). Note that you will need to reload your buffers and sources again.
| `property Enable: boolean read FEnable write SetEnable default true;`
Enable sound. If `False`, then ALContextOpen will not initialize any OpenAL device. This is useful if you simply want to disable any sound output (or OpenAL usage), even when OpenAL library is available. If the OpenAL context is already initialized when setting this, we will eventually close it. (More precisely, we will do ALContextClose and then ALContextOpen again. This behaves correctly.)
| `property DefaultRolloffFactor: Single read FDefaultRolloffFactor write FDefaultRolloffFactor default DefaultDefaultRolloffFactor;`
How the sound is attenuated with the distance. These are used only for spatialized sounds created with PlaySound. The DefaultReferenceDistance and DefaultMaxDistance values are used only if you don't supply explicit values to PlaySound. The exact interpretation of these depends on current DistanceModel. See OpenAL specification for exact equations. In short: Smaller Rolloff Factor makes the attenuation weaker. In particular 0 turns off attenuation by distance. Default is 1. Reference Distance is the distance at which exactly sound gain is heard. Default is 1. Max Distance interpretation depends on the model. For "inverse clamped model", the gain is no longer scaled down after reaching this distance. For linear models, the gain reaches zero at this distance. Default is maximum float (I don't know the interpretation of this for linear model). Our default values follow OpenAL default values.
| `property DefaultReferenceDistance: Single read FDefaultReferenceDistance write FDefaultReferenceDistance default DefaultDefaultReferenceDistance;`
| `property DefaultMaxDistance: Single read FDefaultMaxDistance write FDefaultMaxDistance default DefaultDefaultMaxDistance;`
| `property DistanceModel: TSoundDistanceModel read FDistanceModel write SetDistanceModel default DefaultDistanceModel;`
How the sources are spatialized. For precise meaning, see OpenAL specification of alDistanceModel. Note that some models are actually available only since OpenAL 1.1 version. Older OpenAL versions may (but don't have to) support them through extensions. We will internally do everything possible to request given model, but eventually may fallback on some other model. This probably will not be a problem in practice, as all modern OS versions (Linux distros, Windows OpenAL installers etc.) include OpenAL 1.1. The default distance model, DefaultDistanceModel, is the linear model most conforming to VRML/X3D sound requirements. You can change it if you want (for example, OpenAL default is dmInverseDistanceClamped).
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