Fix spatial audio playback when clip is set after the audio source was enabled

#1622

Source/Engine/Audio/AudioSource.cpp

@@ -265,6 +265,7 @@ void AudioSource::Cleanup()
 void AudioSource::OnClipChanged()
 {
     Stop();
+    _clipChanged = true;
 }
 
 void AudioSource::OnClipLoaded()
@@ -318,6 +319,12 @@ void AudioSource::SetNonStreamingBuffer()
 
 void AudioSource::PlayInternal()
 {
+    if (_clipChanged && SourceIDs.HasItems())
+    {
+        // If clip was changed between source setup (OnEnable) and actual playback start then ensure to flush any runtime properties with the audio backend
+        _clipChanged = false;
+        AudioBackend::Source::SpatialSetupChanged(this);
+    }
     AudioBackend::Source::Play(this);
 
     _isActuallyPlayingSth = true;
@@ -482,6 +489,7 @@ void AudioSource::OnEnable()
 {
     _prevPos = GetPosition();
     _velocity = Vector3::Zero;
+    _clipChanged = false;
 
     Audio::OnAddSource(this);
     GetScene()->Ticking.Update.AddTick<AudioSource, &AudioSource::Update>(this);

Source/Engine/Audio/AudioSource.h

@@ -53,6 +53,7 @@ private:
     bool _loop;
     bool _playOnStart;
     bool _allowSpatialization;
+    bool _clipChanged = false;
 
     bool _isActuallyPlayingSth = false;
     bool _needToUpdateStreamingBuffers = false;