Add FrequenceModulator component (FM synthesis)

ProjectObsidian/Components/Audio/FrequencyModulator.cs

@@ -0,0 +1,82 @@
+using System;
+using FrooxEngine;
+using Elements.Assets;
+
+namespace Obsidian.Components.Audio
+{
+    [Category(new string[] { "Obsidian/Audio" })]
+    public class FrequencyModulator : Component, IAudioSource, IWorldElement
+    {
+        [Range(0f, 1000f, "0.00")]
+        public readonly Sync<float> ModulationIndex;
+
+        public readonly SyncRef<IAudioSource> CarrierSource;
+        public readonly SyncRef<IAudioSource> ModulatorSource;
+
+        private double dspTimeLastUpdate;
+
+        public bool IsActive
+        {
+            get
+            {
+                return CarrierSource.Target != null &&
+                       ModulatorSource.Target != null &&
+                       CarrierSource.Target.IsActive &&
+                       ModulatorSource.Target.IsActive;
+            }
+        }
+
+        public int ChannelCount
+        {
+            get
+            {
+                return CarrierSource.Target?.ChannelCount ?? 0;
+            }
+        }
+
+        protected override void OnAwake()
+        {
+            base.OnAwake();
+            dspTimeLastUpdate = Engine.Current.AudioSystem.DSPTime;
+            ModulationIndex.Value = 100f; // Default modulation index
+        }
+
+        public void Read<S>(Span<S> buffer) where S : unmanaged, IAudioSample<S>
+        {
+            if (!IsActive)
+            {
+                return;
+            }
+
+            int channelCount = ChannelCount;
+            if (channelCount == 0)
+            {
+                return;
+            }
+
+            // Temporary buffers for carrier and modulator sources
+            Span<S> carrierBuffer = stackalloc S[buffer.Length];
+            Span<S> modulatorBuffer = stackalloc S[buffer.Length];
+
+            // Read data from sources
+            CarrierSource.Target.Read(carrierBuffer);
+            ModulatorSource.Target.Read(modulatorBuffer);
+
+            float modulationIndex = ModulationIndex.Value;
+
+            // Apply FM synthesis
+            for (int i = 0; i < buffer.Length; i++)
+            {
+                // Get carrier and modulator values
+                float carrierValue = carrierBuffer[i].AbsoluteAmplitude;
+                float modulatorValue = modulatorBuffer[i].AbsoluteAmplitude;
+
+                // Compute frequency modulation
+                float modulatedValue = (float)(carrierValue * Math.Sin(2 * Math.PI * modulationIndex * modulatorValue));
+
+                // Write modulated value to the buffer
+                buffer[i] = buffer[i].Bias(buffer[i].AbsoluteAmplitude -  modulatedValue);
+            }
+        }
+    }
+}