float computeGain(const AudioMixerClientData& listenerNodeData, const AvatarAudioStream& listeningNodeStream,
const PositionalAudioStream& streamToAdd, const glm::vec3& relativePosition, bool isEcho) {
float gain = 1.0f;
// injector: apply attenuation
if (streamToAdd.getType() == PositionalAudioStream::Injector) {
gain *= reinterpret_cast<const InjectedAudioStream*>(&streamToAdd)->getAttenuationRatio();
// avatar: apply fixed off-axis attenuation to make them quieter as they turn away
} else if (!isEcho && (streamToAdd.getType() == PositionalAudioStream::Microphone)) {
glm::vec3 rotatedListenerPosition = glm::inverse(streamToAdd.getOrientation()) * relativePosition;
// source directivity is based on angle of emission, in local coordinates
glm::vec3 direction = glm::normalize(rotatedListenerPosition);
float angleOfDelivery = fastAcosf(glm::clamp(-direction.z, -1.0f, 1.0f)); // UNIT_NEG_Z is "forward"
const float MAX_OFF_AXIS_ATTENUATION = 0.2f;
const float OFF_AXIS_ATTENUATION_STEP = (1 - MAX_OFF_AXIS_ATTENUATION) / 2.0f;
float offAxisCoefficient = MAX_OFF_AXIS_ATTENUATION + (angleOfDelivery * (OFF_AXIS_ATTENUATION_STEP / PI_OVER_TWO));
gain *= offAxisCoefficient;
// apply master gain, only to avatars
gain *= listenerNodeData.getMasterAvatarGain();
}
auto& audioZones = AudioMixer::getAudioZones();
auto& zoneSettings = AudioMixer::getZoneSettings();
// find distance attenuation coefficient
float attenuationPerDoublingInDistance = AudioMixer::getAttenuationPerDoublingInDistance();
for (int i = 0; i < zoneSettings.length(); ++i) {
if (audioZones[zoneSettings[i].source].contains(streamToAdd.getPosition()) &&
audioZones[zoneSettings[i].listener].contains(listeningNodeStream.getPosition())) {
attenuationPerDoublingInDistance = zoneSettings[i].coefficient;
break;
}
}
// distance attenuation
const float ATTENUATION_START_DISTANCE = 1.0f;
float distance = glm::length(relativePosition);
assert(ATTENUATION_START_DISTANCE > EPSILON);
if (distance >= ATTENUATION_START_DISTANCE) {
// translate the zone setting to gain per log2(distance)
float g = 1.0f - attenuationPerDoublingInDistance;
g = glm::clamp(g, EPSILON, 1.0f);
// calculate the distance coefficient using the distance to this node
float distanceCoefficient = fastExp2f(fastLog2f(g) * fastLog2f(distance/ATTENUATION_START_DISTANCE));
// multiply the current attenuation coefficient by the distance coefficient
gain *= distanceCoefficient;
}
return gain;
}
float AudioMixer::gainForSource(const PositionalAudioStream& streamToAdd,
const AvatarAudioStream& listeningNodeStream, const glm::vec3& relativePosition, bool isEcho) {
float gain = 1.0f;
float distanceBetween = glm::length(relativePosition);
if (distanceBetween < EPSILON) {
distanceBetween = EPSILON;
}
if (streamToAdd.getType() == PositionalAudioStream::Injector) {
gain *= reinterpret_cast<const InjectedAudioStream*>(&streamToAdd)->getAttenuationRatio();
}
if (!isEcho && (streamToAdd.getType() == PositionalAudioStream::Microphone)) {
// source is another avatar, apply fixed off-axis attenuation to make them quieter as they turn away from listener
glm::vec3 rotatedListenerPosition = glm::inverse(streamToAdd.getOrientation()) * relativePosition;
float angleOfDelivery = glm::angle(glm::vec3(0.0f, 0.0f, -1.0f),
glm::normalize(rotatedListenerPosition));
const float MAX_OFF_AXIS_ATTENUATION = 0.2f;
const float OFF_AXIS_ATTENUATION_FORMULA_STEP = (1 - MAX_OFF_AXIS_ATTENUATION) / 2.0f;
float offAxisCoefficient = MAX_OFF_AXIS_ATTENUATION +
(OFF_AXIS_ATTENUATION_FORMULA_STEP * (angleOfDelivery / PI_OVER_TWO));
// multiply the current attenuation coefficient by the calculated off axis coefficient
gain *= offAxisCoefficient;
}
float attenuationPerDoublingInDistance = _attenuationPerDoublingInDistance;
for (int i = 0; i < _zonesSettings.length(); ++i) {
if (_audioZones[_zonesSettings[i].source].contains(streamToAdd.getPosition()) &&
_audioZones[_zonesSettings[i].listener].contains(listeningNodeStream.getPosition())) {
attenuationPerDoublingInDistance = _zonesSettings[i].coefficient;
break;
}
}
if (distanceBetween >= ATTENUATION_BEGINS_AT_DISTANCE) {
// translate the zone setting to gain per log2(distance)
float g = 1.0f - attenuationPerDoublingInDistance;
g = (g < EPSILON) ? EPSILON : g;
g = (g > 1.0f) ? 1.0f : g;
// calculate the distance coefficient using the distance to this node
float distanceCoefficient = exp2f(log2f(g) * log2f(distanceBetween/ATTENUATION_BEGINS_AT_DISTANCE));
// multiply the current attenuation coefficient by the distance coefficient
gain *= distanceCoefficient;
}
return gain;
}
float computeGain(float masterListenerGain, const AvatarAudioStream& listeningNodeStream,
const PositionalAudioStream& streamToAdd, const glm::vec3& relativePosition, float distance, bool isEcho) {
float gain = 1.0f;
// injector: apply attenuation
if (streamToAdd.getType() == PositionalAudioStream::Injector) {
gain *= reinterpret_cast<const InjectedAudioStream*>(&streamToAdd)->getAttenuationRatio();
// avatar: apply fixed off-axis attenuation to make them quieter as they turn away
} else if (!isEcho && (streamToAdd.getType() == PositionalAudioStream::Microphone)) {
glm::vec3 rotatedListenerPosition = glm::inverse(streamToAdd.getOrientation()) * relativePosition;
// source directivity is based on angle of emission, in local coordinates
glm::vec3 direction = glm::normalize(rotatedListenerPosition);
float angleOfDelivery = fastAcosf(glm::clamp(-direction.z, -1.0f, 1.0f)); // UNIT_NEG_Z is "forward"
const float MAX_OFF_AXIS_ATTENUATION = 0.2f;
const float OFF_AXIS_ATTENUATION_STEP = (1 - MAX_OFF_AXIS_ATTENUATION) / 2.0f;
float offAxisCoefficient = MAX_OFF_AXIS_ATTENUATION + (angleOfDelivery * (OFF_AXIS_ATTENUATION_STEP / PI_OVER_TWO));
gain *= offAxisCoefficient;
// apply master gain, only to avatars
gain *= masterListenerGain;
}
auto& audioZones = AudioMixer::getAudioZones();
auto& zoneSettings = AudioMixer::getZoneSettings();
// find distance attenuation coefficient
float attenuationPerDoublingInDistance = AudioMixer::getAttenuationPerDoublingInDistance();
for (const auto& settings : zoneSettings) {
if (audioZones[settings.source].area.contains(streamToAdd.getPosition()) &&
audioZones[settings.listener].area.contains(listeningNodeStream.getPosition())) {
attenuationPerDoublingInDistance = settings.coefficient;
break;
}
}
if (attenuationPerDoublingInDistance < 0.0f) {
// translate a negative zone setting to distance limit
const float MIN_DISTANCE_LIMIT = ATTN_DISTANCE_REF + 1.0f; // silent after 1m
float distanceLimit = std::max(-attenuationPerDoublingInDistance, MIN_DISTANCE_LIMIT);
// calculate the LINEAR attenuation using the distance to this node
// reference attenuation of 0dB at distance = ATTN_DISTANCE_REF
float d = distance - ATTN_DISTANCE_REF;
gain *= std::max(1.0f - d / (distanceLimit - ATTN_DISTANCE_REF), 0.0f);
gain = std::min(gain, ATTN_GAIN_MAX);
} else {
// translate a positive zone setting to gain per log2(distance)
const float MIN_ATTENUATION_COEFFICIENT = 0.001f; // -60dB per log2(distance)
float g = glm::clamp(1.0f - attenuationPerDoublingInDistance, MIN_ATTENUATION_COEFFICIENT, 1.0f);
// calculate the LOGARITHMIC attenuation using the distance to this node
// reference attenuation of 0dB at distance = ATTN_DISTANCE_REF
float d = (1.0f / ATTN_DISTANCE_REF) * std::max(distance, HRTF_NEARFIELD_MIN);
gain *= fastExp2f(fastLog2f(g) * fastLog2f(d));
gain = std::min(gain, ATTN_GAIN_MAX);
}
return gain;
}
