AudioMixerClientData::IgnoreZone& AudioMixerClientData::IgnoreZoneMemo::get(unsigned int frame) {
// check for a memoized zone
if (frame != _frame.load(std::memory_order_acquire)) {
AvatarAudioStream* stream = _data.getAvatarAudioStream();
// get the initial dimensions from the stream
glm::vec3 corner = stream ? stream->getAvatarBoundingBoxCorner() : glm::vec3(0);
glm::vec3 scale = stream ? stream->getAvatarBoundingBoxScale() : glm::vec3(0);
// enforce a minimum scale
static const glm::vec3 MIN_IGNORE_BOX_SCALE = glm::vec3(0.3f, 1.3f, 0.3f);
if (glm::any(glm::lessThan(scale, MIN_IGNORE_BOX_SCALE))) {
scale = MIN_IGNORE_BOX_SCALE;
}
// quadruple the scale (this is arbitrary number chosen for comfort)
const float IGNORE_BOX_SCALE_FACTOR = 4.0f;
scale *= IGNORE_BOX_SCALE_FACTOR;
// create the box (we use a box for the zone for convenience)
AABox box(corner, scale);
// update the memoized zone
// This may be called by multiple threads concurrently,
// so take a lock and only update the memo if this call is first.
// This prevents concurrent updates from invalidating the returned reference
// (contingent on the preconditions listed in the header).
std::lock_guard<std::mutex> lock(_mutex);
if (frame != _frame.load(std::memory_order_acquire)) {
_zone = box;
unsigned int oldFrame = _frame.exchange(frame, std::memory_order_release);
Q_UNUSED(oldFrame);
}
}
return _zone;
}
