engine almost working, backup before adding gas types.

Audio/AudioOutputStream.cs

@@ -0,0 +1,53 @@
+using SFML.Audio;
+using SFML.System;
+
+namespace FluidSim.Audio
+{
+    public class AudioOutputStream : SoundStream
+    {
+        private readonly SimulationRingBuffer _sourceBuffer;
+        private double _speed = 1.0;   // non‑volatile, accessed with Volatile.Read/Write
+
+        public AudioOutputStream(SimulationRingBuffer sourceBuffer)
+        {
+            _sourceBuffer = sourceBuffer;
+            // 2 channels, 44.1 kHz, stereo
+            Initialize(2, 44100, new[] { SoundChannel.FrontLeft, SoundChannel.FrontRight });
+        }
+
+        /// <summary>Playback speed (0.01 … 1.0 or higher for catch‑up).</summary>
+        public double Speed
+        {
+            get => Volatile.Read(ref _speed);
+            set => Volatile.Write(ref _speed, value);
+        }
+
+        protected override bool OnGetData(out short[] samples)
+        {
+            const int monoBlockSize = 512;
+            float[] temp = new float[monoBlockSize];
+
+            int read = _sourceBuffer.ReadInterpolated(temp, monoBlockSize, Speed);
+            samples = new short[monoBlockSize * 2];
+
+            if (read > 0)
+            {
+                for (int i = 0; i < read; i++)
+                {
+                    float clamped = Math.Clamp(temp[i], -1f, 1f);
+                    short final = (short)(clamped * short.MaxValue);
+                    samples[i * 2] = final;      // left
+                    samples[i * 2 + 1] = final;  // right
+                }
+            }
+            // Fill rest with silence
+            for (int i = read * 2; i < samples.Length; i++)
+                samples[i] = 0;
+
+            return true;
+        }
+
+        protected override void OnSeek(Time timeOffset) =>
+            throw new NotSupportedException();
+    }
+}