Positional channel configuration

Configure positional channels for spatial audio in 3D environments.

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If a game has joined a positional channel, it must frequently update the Vivox SDK with the position and orientation of the user in the 3D space that is associated with that channel. The client does this by calling the

ChannelSession::Set3DPosition

method on a

ChannelSession

ChannelType::Positional

that has its

AudioState

connected. You can additionally have your

TextState

connected, but to set your position, you must connect to audio. A participant's location in a positional channel affects who they can hear, and also the perceived loudness and direction of other players’ voices. With text enabled, location limits the delivery of text messages to only users within the audible vicinity of the sender. Positional channels use a right-hand coordinate system. When the player avatar is standing facing directly forward, the following criteria applies:

The positive X-axis is to the avatar's right.
The positive Y-axis runs from the avatar's feet upward through their head.
The positive Z-axis runs from the avatar's chest out through their back.

When a player joins a positional channel, the player avatar is placed at a null position until they move to a position.

注

Unreal Engine 4 uses a left-hand, Z-up world coordinate system. Do not perform this conversion manually when using

Set3DPosition

because the conversion between coordinate systems is handled internally by the Vivox SDK. However, you can provide an actor’s position and orientation by using standard AActor methods.

You can set the position of the avatar's mouth independently of the avatar's ears. These are respectively referred to as the speaker position and the listener position, and they share coordinates in most scenarios. Because the positions are independent, this allows for effects like an "audio zoom," where a character who is using something like a shotgun microphone could be configured to hear voice as though they were closer to the target, but they are still only speaking to those immediately around them. In addition to position, the listener can also have its orientation set to accurately render audio panning. However, the speaker cannot have its orientation set; spoken voices are treated as omni-directional audio “point sources” and are unaffected by the speaker’s orientation. After you set up and join a positional channel with any configured 3D properties, you then report your actor's position and orientation to the Vivox SDK. The following code displays an example of how to set a user's position in a positional channel:


void UMyClass::Tick(float DeltaTime){    AActor MyPlayerCharacter;    /* . . . */    float PositionalUpdateRate = 0.2f; // Send position and orientation update every 0.2 seconds.    static float NextUpdateTime = UGameplayStatics::GetRealTimeSeconds(GetWorld()) + PositionalUpdateRate;    if (UGameplayStatics::GetRealTimeSeconds(GetWorld()) > NextUpdateTime)    {        NextUpdateTime += PositionalUpdateRate;        Update3DPosition(MyPlayerCharacter);    }    /* . . . */}void UMyClass::Update3DPosition(AActor *Actor){    // Sample method GetPositionalChannel returns the valid positional channel the player is in    ChannelId PositionalChannel = GetPositionalChannel();    // Update cached 3D position and orientation.    m_cachedPosition.SetValue(Actor->GetActorLocation());    m_cachedForwardVector.SetValue(Actor->GetActorForwardVector());    m_cachedUpVector.SetValue(Actor->GetActorUpVector());    // Return If there's no change from cached values.    if (!Get3DValuesAreDirty())    {        return;    }    // Send new position and orientation to current positional channel    MyLoginSession.GetChannelSession(PositionalChannel).Set3DPosition( m_cachedPosition.GetValue(), m_cachedPosition.GetValue(), m_cachedForwardVector.GetValue(), m_cachedUpVector.GetValue() );    Clear3DValuesAreDirty();}

This code displays methods for limiting the number of 3D positional updates that are sent. For example, a time tracking technique is used in the

Tick()

function to rate limit update attempts to a reasonable number of times per second. Also, in the sample method

Update3DPosition()

, a

CachedProperty

template class caches the player’s position and orientation. If the player has moved since last calling

IChannelSession::Set3DPosition

, then utility functions check and reset their Boolean triggers.

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