audio interpolation support + audio threading

src/Audio/AudioDevice.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Collections.Generic;
 using System.Threading;
+using EasingFunction = System.Func<float, float>;
 
 namespace MoonWorks.Audio
 {
@@ -29,10 +30,16 @@ namespace MoonWorks.Audio
 		private readonly List<WeakReference<AudioResource>> resources = new List<WeakReference<AudioResource>>();
 		private readonly List<WeakReference<StreamingSound>> streamingSounds = new List<WeakReference<StreamingSound>>();
 
+		private AudioTweenPool AudioTweenPool = new AudioTweenPool();
+		private readonly List<AudioTween> AudioTweens = new List<AudioTween>();
+
 		private const int Step = 200;
 		private TimeSpan UpdateInterval;
+		private System.Diagnostics.Stopwatch TickStopwatch = new System.Diagnostics.Stopwatch();
+		private long previousTickTime;
 		private Thread Thread;
 		private AutoResetEvent WakeSignal;
+		private readonly object StateLock = new object();
 
 		private bool IsDisposed;
 
@@ -119,13 +126,19 @@ namespace MoonWorks.Audio
 			Thread = new Thread(ThreadMain);
 			Thread.IsBackground = true;
 			Thread.Start();
+
+			TickStopwatch.Start();
+			previousTickTime = 0;
 		}
 
 		private void ThreadMain()
 		{
 			while (!IsDisposed)
+			{
+				lock (StateLock)
 				{
 					ThreadMainTick();
+				}
 
 				WakeSignal.WaitOne(UpdateInterval);
 			}
@@ -133,6 +146,10 @@ namespace MoonWorks.Audio
 
 		private void ThreadMainTick()
 		{
+			long tickDelta = TickStopwatch.Elapsed.Ticks - previousTickTime;
+			previousTickTime = TickStopwatch.Elapsed.Ticks;
+			float elapsedSeconds = (float) tickDelta / System.TimeSpan.TicksPerSecond;
+
 			for (var i = streamingSounds.Count - 1; i >= 0; i--)
 			{
 				var weakReference = streamingSounds[i];
@@ -145,11 +162,26 @@ namespace MoonWorks.Audio
 					streamingSounds.RemoveAt(i);
 				}
 			}
+
+			lock (AudioTweens)
+			{
+				for (var i = AudioTweens.Count - 1; i >= 0; i--)
+				{
+					bool finished = true;
+					var audioTween = AudioTweens[i];
+
+					if (audioTween.SoundInstanceReference.TryGetTarget(out var soundInstance))
+					{
+						finished = UpdateAudioTween(audioTween, soundInstance, elapsedSeconds);
 					}
 
-		internal void WakeThread()
+					if (finished)
 					{
-			WakeSignal.Set();
+						AudioTweenPool.Free(audioTween);
+						AudioTweens.RemoveAt(i);
+					}
+				}
+			}
 		}
 
 		public void SyncPlay()
@@ -157,14 +189,91 @@ namespace MoonWorks.Audio
 			FAudio.FAudio_CommitChanges(Handle, 1);
 		}
 
+		internal void CreateTween(
+			SoundInstance soundInstance,
+			AudioTweenProperty property,
+			EasingFunction easingFunction,
+			float start,
+			float end,
+			float duration
+		) {
+			var tween = AudioTweenPool.Obtain();
+			tween.SoundInstanceReference = new WeakReference<SoundInstance>(soundInstance);
+			tween.Property = property;
+			tween.EasingFunction = easingFunction;
+			tween.Start = start;
+			tween.End = end;
+			tween.Duration = duration;
+			tween.Time = 0;
+
+			lock (AudioTweens)
+			{
+				AudioTweens.Add(tween);
+			}
+		}
+
+		private bool UpdateAudioTween(AudioTween audioTween, SoundInstance soundInstance, float delta)
+		{
+			float value;
+			audioTween.Time += delta;
+
+			if (audioTween.Time > audioTween.Duration)
+			{
+				value = audioTween.End;
+			}
+			else
+			{
+				value = MoonWorks.Math.Easing.Interp(
+					audioTween.Start,
+					audioTween.End,
+					audioTween.Time,
+					audioTween.Duration,
+					audioTween.EasingFunction
+				);
+			}
+
+			switch (audioTween.Property)
+			{
+				case AudioTweenProperty.Pan:
+					soundInstance.Pan = value;
+					break;
+
+				case AudioTweenProperty.Pitch:
+					soundInstance.Pitch = value;
+					break;
+
+				case AudioTweenProperty.Volume:
+					soundInstance.Volume = value;
+					break;
+
+				case AudioTweenProperty.FilterFrequency:
+					soundInstance.FilterFrequency = value;
+					break;
+
+				case AudioTweenProperty.Reverb:
+					soundInstance.Reverb = value;
+					break;
+			}
+
+			return audioTween.Time > audioTween.Duration;
+		}
+
+		internal void WakeThread()
+		{
+			WakeSignal.Set();
+		}
+
 		internal void AddDynamicSoundInstance(StreamingSound instance)
+		{
+			lock (StateLock)
 			{
 				streamingSounds.Add(new WeakReference<StreamingSound>(instance));
 			}
+		}
 
 		internal void AddResourceReference(WeakReference<AudioResource> resourceReference)
 		{
-			lock (resources)
+			lock (StateLock)
 			{
 				resources.Add(resourceReference);
 			}
@@ -172,7 +281,7 @@ namespace MoonWorks.Audio
 
 		internal void RemoveResourceReference(WeakReference<AudioResource> resourceReference)
 		{
-			lock (resources)
+			lock (StateLock)
 			{
 				resources.Remove(resourceReference);
 			}
@@ -181,6 +290,8 @@ namespace MoonWorks.Audio
 		protected virtual void Dispose(bool disposing)
 		{
 			if (!IsDisposed)
+			{
+				lock (StateLock)
 				{
 					if (disposing)
 					{
@@ -202,6 +313,7 @@ namespace MoonWorks.Audio
 					IsDisposed = true;
 				}
 			}
+		}
 
 		// TODO: override finalizer only if 'Dispose(bool disposing)' has code to free unmanaged resources
 		~AudioDevice()

src/Audio/AudioTween.cs

@@ -0,0 +1,48 @@
+using System.Collections.Generic;
+using EasingFunction = System.Func<float, float>;
+
+namespace MoonWorks.Audio
+{
+	internal enum AudioTweenProperty
+	{
+		Pan,
+		Pitch,
+		Volume,
+		FilterFrequency,
+		Reverb
+	}
+
+	internal class AudioTween
+	{
+		public System.WeakReference<SoundInstance> SoundInstanceReference;
+		public AudioTweenProperty Property;
+		public EasingFunction EasingFunction;
+		public float Time;
+		public float Start;
+		public float End;
+		public float Duration;
+	}
+
+	internal class AudioTweenPool
+	{
+		private Queue<AudioTween> Tweens = new Queue<AudioTween>();
+
+		public AudioTween Obtain()
+		{
+			if (Tweens.Count > 0)
+			{
+				var tween = Tweens.Dequeue();
+				return tween;
+			}
+			else
+			{
+				return new AudioTween();
+			}
+		}
+
+		public void Free(AudioTween tween)
+		{
+			Tweens.Enqueue(tween);
+		}
+	}
+}

src/Audio/SoundInstance.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Runtime.InteropServices;
+using EasingFunction = System.Func<float, float>;
 
 namespace MoonWorks.Audio
 {
@@ -21,7 +22,7 @@ namespace MoonWorks.Audio
 		public float Pan
 		{
 			get => pan;
-			set
+			internal set
 			{
 				pan = value;
 
@@ -52,7 +53,7 @@ namespace MoonWorks.Audio
 		public float Pitch
 		{
 			get => pitch;
-			set
+			internal set
 			{
 				pitch = Math.MathHelper.Clamp(value, -1f, 1f);
 				UpdatePitch();
@@ -63,7 +64,7 @@ namespace MoonWorks.Audio
 		public float Volume
 		{
 			get => volume;
-			set
+			internal set
 			{
 				volume = value;
 				FAudio.FAudioVoice_SetVolume(Voice, volume, 0);
@@ -80,10 +81,10 @@ namespace MoonWorks.Audio
 			OneOverQ = 1f
 		};
 
-		private float FilterFrequency
+		public float FilterFrequency
 		{
 			get => filterParameters.Frequency;
-			set
+			internal set
 			{
 				value = System.Math.Clamp(value, 0.01f, MAX_FILTER_FREQUENCY);
 				filterParameters.Frequency = value;
@@ -156,7 +157,7 @@ namespace MoonWorks.Audio
 		public unsafe float Reverb
 		{
 			get => reverb;
-			set
+			internal set
 			{
 				if (ReverbEffect != null)
 				{
@@ -188,7 +189,7 @@ namespace MoonWorks.Audio
 			}
 		}
 
-		public SoundInstance(
+		public unsafe SoundInstance(
 			AudioDevice device,
 			ushort formatTag,
 			ushort bitsPerSample,
@@ -277,6 +278,58 @@ namespace MoonWorks.Audio
 			ReverbEffect = reverbEffect;
 		}
 
+		// TODO: since we're using setters now, could just get rid of the property setters
+
+		public void SetPan(float targetValue)
+		{
+			Pan = targetValue;
+		}
+
+		public void SetPan(float targetValue, float duration, EasingFunction easingFunction)
+		{
+			Device.CreateTween(this, AudioTweenProperty.Pan, easingFunction, Pan, targetValue, duration);
+		}
+
+		public void SetPitch(float targetValue)
+		{
+			Pitch = targetValue;
+		}
+
+		public void SetPitch(float targetValue, float duration, EasingFunction easingFunction)
+		{
+			Device.CreateTween(this, AudioTweenProperty.Pitch, easingFunction, Pan, targetValue, duration);
+		}
+
+		public void SetVolume(float targetValue)
+		{
+			Volume = targetValue;
+		}
+
+		public void SetVolume(float targetValue, float duration, EasingFunction easingFunction)
+		{
+			Device.CreateTween(this, AudioTweenProperty.Volume, easingFunction, Volume, targetValue, duration);
+		}
+
+		public void SetFilterFrequency(float targetValue)
+		{
+			FilterFrequency = targetValue;
+		}
+
+		public void SetFilterFrequency(float targetValue, float duration, EasingFunction easingFunction)
+		{
+			Device.CreateTween(this, AudioTweenProperty.FilterFrequency, easingFunction, FilterFrequency, targetValue, duration);
+		}
+
+		public void SetReverb(float targetValue)
+		{
+			Reverb = targetValue;
+		}
+
+		public void SetReverb(float targetValue, float duration, EasingFunction easingFunction)
+		{
+			Device.CreateTween(this, AudioTweenProperty.Reverb, easingFunction, Volume, targetValue, duration);
+		}
+
 		public abstract void Play();
 		public abstract void QueueSyncPlay();
 		public abstract void Pause();
@@ -297,14 +350,12 @@ namespace MoonWorks.Audio
 			);
 
 			dspSettings.pMatrixCoefficients = (nint) NativeMemory.Alloc(memsize);
-			unsafe
-			{
 			byte* memPtr = (byte*) dspSettings.pMatrixCoefficients;
 			for (uint i = 0; i < memsize; i += 1)
 			{
 				memPtr[i] = 0;
 			}
-			}
+
 			SetPanMatrixCoefficients();
 		}