From b049b4f88dad22bd6bc774a55c583294441baa1a Mon Sep 17 00:00:00 2001
From: Nicky McDonald <43690021+nickyMcDonald@users.noreply.github.com>
Date: Sat, 24 Feb 2024 03:44:13 -0500
Subject: [PATCH] AttachAudioMixedProcessor Utils for easy callback (#215)

---
 Raylib-cs/types/AudioCallback.cs | 10 ++++++++++
 Raylib-cs/types/AudioMixed.cs    | 23 +++++++++++++++++++++++
 Raylib-cs/types/Raylib.Utils.cs  | 24 ++++++++++++++++++++++++
 3 files changed, 57 insertions(+)
 create mode 100644 Raylib-cs/types/AudioCallback.cs
 create mode 100644 Raylib-cs/types/AudioMixed.cs

diff --git a/Raylib-cs/types/AudioCallback.cs b/Raylib-cs/types/AudioCallback.cs
new file mode 100644
index 0000000..2f7b372
--- /dev/null
+++ b/Raylib-cs/types/AudioCallback.cs
@@ -0,0 +1,10 @@
+using System;
+
+namespace Raylib_cs;
+
+/// <summary>
+/// Audio stream processor.
+/// Used with Raylib.AttachAudioMixedProcessor()
+/// and Raylib.DetachAudioMixedProcessor()
+/// </summary>
+public delegate void AudioCallback<T>(Span<T> buffer);
diff --git a/Raylib-cs/types/AudioMixed.cs b/Raylib-cs/types/AudioMixed.cs
new file mode 100644
index 0000000..bf98491
--- /dev/null
+++ b/Raylib-cs/types/AudioMixed.cs
@@ -0,0 +1,23 @@
+using System;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+namespace Raylib_cs;
+
+internal static unsafe class AudioMixed
+{
+    public static AudioCallback<float> Callback = null;
+
+    [UnmanagedCallersOnly(CallConvs = new[]
+    {
+        typeof(CallConvCdecl),
+    })]
+    public static void Processor(void* buffer, uint frames)
+    {
+        // The buffer is stereo audio, so we need to double our frame count.
+        frames = Math.Min(frames * 2, int.MaxValue);
+
+        Span<float> floats = new(buffer, (int)frames);
+        Callback?.Invoke(floats);
+    }
+}
diff --git a/Raylib-cs/types/Raylib.Utils.cs b/Raylib-cs/types/Raylib.Utils.cs
index c3b2f1d..46ba915 100644
--- a/Raylib-cs/types/Raylib.Utils.cs
+++ b/Raylib-cs/types/Raylib.Utils.cs
@@ -1261,6 +1261,30 @@ public static unsafe partial class Raylib
         }
     }
 
+    /// <summary>
+    /// Attach audio stream processor to the entire audio pipeline
+    /// </summary>
+    public static void AttachAudioMixedProcessor(AudioCallback<float> processor)
+    {
+        if (AudioMixed.Callback == null)
+        {
+            AudioMixed.Callback = processor;
+            AttachAudioMixedProcessor(&AudioMixed.Processor);
+        }
+    }
+
+    /// <summary>
+    /// Detach audio stream processor from the entire audio pipeline
+    /// </summary>
+    public static void DetachAudioMixedProcessor(AudioCallback<float> processor)
+    {
+        if (AudioMixed.Callback == processor)
+        {
+            DetachAudioMixedProcessor(&AudioMixed.Processor);
+            AudioMixed.Callback = null;
+        }
+    }
+
     public static string SubText(this string input, int position, int length)
     {
         return input.Substring(position, Math.Min(length, input.Length));