Lots of improvements. Better UI, time scrolling, scenario system

Core/Simulation.cs

@@ -1,74 +0,0 @@
-using System;
-using FluidSim.Components;
-using FluidSim.Interfaces;
-using FluidSim.Utils;
-
-namespace FluidSim.Core
-{
-    public static class Simulation
-    {
-        private static Solver solver;
-        private static Pipe1D pipe;
-        private static int stepCount;
-        private static double time;
-        private static double dt;
-        private static float sample;
-        private static double ambientPressure = 1.0 * Units.atm;
-
-        private static bool enableLogging = false;
-
-        public static void Initialize(int sampleRate)
-        {
-            dt = 1.0 / sampleRate;
-
-            double length = 2;
-            double radius = 20 * Units.mm;
-            double area = Units.AreaFromDiameter(radius);
-
-            pipe = new Pipe1D(length, area, sampleRate, forcedCellCount: 80);
-            pipe.SetUniformState(1.225, 0.0, ambientPressure);
-
-            solver = new Solver();
-            solver.SetTimeStep(dt);
-            solver.AddPipe(pipe);
-            solver.SetPipeBoundary(pipe, isLeft: true, BoundaryType.OpenEnd, ambientPressure);
-            solver.SetPipeBoundary(pipe, isLeft: false, BoundaryType.ClosedEnd);
-
-            // Excite the pipe with an initial pressure pulse near the open end
-            int pulseCells = 5;
-            double pulsePressure = 4 * ambientPressure;
-            for (int i = 0; i < pulseCells; i++)
-                pipe.SetCellState(i, 1.225, 0.0, pulsePressure);
-        }
-
-        public static float Process()
-        {
-            sample = solver.Step();
-            time += dt;
-            stepCount++;
-
-            // Override the audio sample with mid-pipe pressure deviation
-            double pMid = pipe.GetPressureAtFraction(0.5);
-            sample = (float)((pMid - ambientPressure) / ambientPressure);
-
-            Log();
-            return sample;
-        }
-
-        public static void Log()
-        {
-            if (!enableLogging) return;
-            if (stepCount % 10 == 0 && stepCount < 1000)
-            {
-                double pMid = pipe.GetPressureAtFraction(0.5);
-                double pOpen = pipe.GetCellPressure(0);
-                double pClosed = pipe.GetCellPressure(pipe.GetCellCount() - 1);
-                Console.WriteLine(
-                    $"t = {time * 1e3:F3} ms  Step {stepCount:D4}: " +
-                    $"Sample: = {sample:F3}, " +
-                    $"P_mid = {pMid:F2} Pa ({pMid / ambientPressure:F4} atm), " +
-                    $"P_open = {pOpen:F2} Pa, P_closed = {pClosed:F2} Pa");
-            }
-        }
-    }
-}

Program.cs

@@ -9,61 +9,172 @@ namespace FluidSim;
 public class Program
 {
     private const int SampleRate = 44100;
+    private const double DrawFrequency = 60.0;
+    private static Scenario scenario;
+
+    // Speed control
+    private static double desiredSpeed = 1.0;
+    private static double currentSpeed = desiredSpeed;
+    private const double MinSpeed = 0.0001;
+    private const double MaxSpeed = 1.0;
+    private const double ScrollFactor = 1.1;
+
+    // Space‑toggle state
+    private static double lastDesiredSpeed = 0.1;   // remembers the last non‑1.0 scroll speed
+    private static bool isRealTime = true;          // true when desiredSpeed == 1.0
+
     private static volatile bool running = true;
 
     public static void Main()
     {
         var mode = new VideoMode(new Vector2u(1280, 720));
-        var window = new RenderWindow(mode, "Fluid Simulation");
+        var window = new RenderWindow(mode, "Pipe Resonator");
         window.SetVerticalSyncEnabled(true);
         window.Closed += (_, _) => { running = false; window.Close(); };
+        window.MouseWheelScrolled += OnMouseWheel;
+        window.KeyPressed += OnKeyPressed;
 
-        var soundEngine = new SoundEngine(bufferCapacity: 2048);
+        var soundEngine = new SoundEngine(bufferCapacity: 16384);
         soundEngine.Volume = 70;
         soundEngine.Start();
 
-        double lastAudioTime = 0.0;
+        scenario = new PipeResonatorScenario();
+        scenario.Initialize(SampleRate);
+
         var stopwatch = Stopwatch.StartNew();
+        double lastDrawTime = 0.0;
+        double drawInterval = 1.0 / DrawFrequency;
+        double lastSpeedUpdateTime = stopwatch.Elapsed.TotalSeconds;
 
-        int warmupSamples = SampleRate / 2;
+        // Resampling buffer
-        float[] warmup = new float[warmupSamples];
+        List<float> simBuffer = new List<float>(4096);
-        for (int i = 0; i < warmupSamples; i++)
+        double readIndex = 0.0;
-            warmup[i] = 0;
 
-        soundEngine.WriteSamples(warmup, warmupSamples);
+        for (int i = 0; i < 4; i++)
-        lastAudioTime = stopwatch.Elapsed.TotalSeconds;
+            simBuffer.Add(scenario.Process());
 
-        const int chunkSize = 2048;
+        long totalSimSteps = simBuffer.Count;
-        float[] buffer = new float[chunkSize];
+        long totalOutputSamples = 0;
 
-        Simulation.Initialize(SampleRate);
+        double lastRealTime = stopwatch.Elapsed.TotalSeconds;
+        const int outputChunk = 256;
+        float[] outputBuf = new float[outputChunk];
 
         while (window.IsOpen)
         {
             window.DispatchEvents();
 
-            double currentTime = stopwatch.Elapsed.TotalSeconds;
+            double currentRealTime = stopwatch.Elapsed.TotalSeconds;
-            double elapsed = currentTime - lastAudioTime;
+            double dtSpeed = currentRealTime - lastSpeedUpdateTime;
-            int samplesNeeded = (int)(elapsed * SampleRate);
+            lastSpeedUpdateTime = currentRealTime;
 
-            while (samplesNeeded > 0 && running)
+            // Smoothly transition currentSpeed → desiredSpeed
+            // When toggling, desiredSpeed jumps, but currentSpeed follows with a smooth lerp
+            double smoothingRate = 8.0;   // higher = faster catch‑up
+            currentSpeed += (desiredSpeed - currentSpeed) * (1.0 - Math.Exp(-smoothingRate * dtSpeed));
+
+            // ---------- Generate audio ----------
+            double targetAudioClock = currentRealTime + 0.05;
+
+            while (totalOutputSamples < targetAudioClock * SampleRate && running)
             {
-                int toGenerate = Math.Min(samplesNeeded, chunkSize);
+                int toGenerate = (int)Math.Min(
+                    (long)outputChunk,
+                    (long)(targetAudioClock * SampleRate) - totalOutputSamples
+                );
+                if (toGenerate <= 0) break;
+
+                double maxIndex = readIndex + (toGenerate - 1) * currentSpeed + 2;
+                int requiredSimIndex = (int)Math.Ceiling(maxIndex);
+                while (simBuffer.Count - 1 < requiredSimIndex)
+                {
+                    simBuffer.Add(scenario.Process());
+                    totalSimSteps++;
+                }
+
                 for (int i = 0; i < toGenerate; i++)
                 {
-                    buffer[i] = Simulation.Process();
+                    int i0 = (int)readIndex;
+                    int i1 = i0 + 1;
+                    double frac = readIndex - i0;
+
+                    float y0 = simBuffer[Math.Clamp(i0, 0, simBuffer.Count - 1)];
+                    float y1 = simBuffer[Math.Clamp(i1, 0, simBuffer.Count - 1)];
+                    outputBuf[i] = (float)(y0 + (y1 - y0) * frac);
+
+                    readIndex += currentSpeed;
+
+                    while (readIndex >= 1.0 && simBuffer.Count > 2)
+                    {
+                        simBuffer.RemoveAt(0);
+                        readIndex -= 1.0;
                     }
-                soundEngine.WriteSamples(buffer, toGenerate);
-                samplesNeeded -= toGenerate;
                 }
 
-            lastAudioTime = currentTime;
+                int accepted = soundEngine.WriteSamples(outputBuf, toGenerate);
+                totalOutputSamples += accepted;
+
+                if (accepted < toGenerate)
+                    break;
+            }
+
+            // ---------- Drawing & title ----------
+            if (currentRealTime - lastDrawTime >= drawInterval)
+            {
+                double actualSpeed = totalOutputSamples / (currentRealTime * SampleRate);
+                double simTime = totalSimSteps / (double)SampleRate;
+                string toggleHint = isRealTime ? "[Space] slow mo" : "[Space] real time";
+                window.SetTitle(
+                    $"{toggleHint}  Sim: {simTime:F2}s | " +
+                    $"Speed: {currentSpeed:F4}x → {desiredSpeed:F4}x | " +
+                    $"Actual: {actualSpeed:F2}x"
+                );
 
                 window.Clear(Color.Black);
+                scenario.Draw(window);
                 window.Display();
+                lastDrawTime = currentRealTime;
+            }
         }
 
         soundEngine.Dispose();
         window.Dispose();
     }
+
+    private static void OnMouseWheel(object? sender, MouseWheelScrollEventArgs e)
+    {
+        bool wasRealTime = Math.Abs(desiredSpeed - 1.0) < 1e-6;
+
+        if (e.Delta > 0)
+            desiredSpeed *= ScrollFactor;
+        else if (e.Delta < 0)
+            desiredSpeed /= ScrollFactor;
+
+        desiredSpeed = Math.Clamp(desiredSpeed, MinSpeed, MaxSpeed);
+
+        // Update the remembered slow-mo speed (unless we are exactly at 1.0)
+        if (!wasRealTime || Math.Abs(desiredSpeed - 1.0) > 1e-6)
+            lastDesiredSpeed = desiredSpeed;
+
+        // Update isRealTime flag
+        isRealTime = Math.Abs(desiredSpeed - 1.0) < 1e-6;
+    }
+
+    private static void OnKeyPressed(object? sender, KeyEventArgs e)
+    {
+        if (e.Code == Keyboard.Key.Space)
+        {
+            if (isRealTime)
+            {
+                // Switch to the remembered slow speed
+                desiredSpeed = lastDesiredSpeed;
+            }
+            else
+            {
+                // Switch back to real time
+                desiredSpeed = 1.0;
+            }
+            isRealTime = !isRealTime;
+        }
+    }
 }

Scenarios/PipeResonatorScenario.cs

@@ -0,0 +1,183 @@
+using FluidSim.Components;
+using FluidSim.Interfaces;
+using FluidSim.Utils;
+using SFML.Graphics;
+using SFML.System;
+using System;
+
+namespace FluidSim.Core
+{
+    public class PipeResonatorScenario : Scenario
+    {
+        private Solver solver;
+        private Pipe1D pipe;
+        private int stepCount;
+        private double time;
+        private double dt;
+        private double ambientPressure = 1.0 * Units.atm;
+        private bool enableLogging = true;
+
+        public override void Initialize(int sampleRate)
+        {
+            dt = 1.0 / sampleRate;
+
+            double length = 0.5;
+            double radius = 50 * Units.mm;
+            double area = Units.AreaFromDiameter(radius);
+
+            pipe = new Pipe1D(length, area, sampleRate, forcedCellCount: 80);
+            pipe.SetUniformState(1.225, 0.0, ambientPressure);
+
+            solver = new Solver();
+            solver.SetTimeStep(dt);
+            solver.AddPipe(pipe);
+            solver.SetPipeBoundary(pipe, isLeft: true, BoundaryType.OpenEnd, ambientPressure);
+            solver.SetPipeBoundary(pipe, isLeft: false, BoundaryType.ClosedEnd);
+
+            // Initial pressure pulse
+            int pulseCells = 5;
+            double pulsePressure = 2 * ambientPressure;
+            for (int i = 0; i < pulseCells; i++)
+                pipe.SetCellState(i, 1.225, 0.0, pulsePressure);
+        }
+
+        public override float Process()
+        {
+            float sample = solver.Step();
+            time += dt;
+            stepCount++;
+
+            double pMid = pipe.GetPressureAtFraction(0.5);
+            sample = (float)((pMid - ambientPressure) / ambientPressure);
+
+            Log(sample);
+            return sample;
+        }
+
+        private void Log(float sample)
+        {
+            if (!enableLogging) return;
+            if (stepCount % 10 == 0 && stepCount < 1000)
+            {
+                double pMid = pipe.GetPressureAtFraction(0.5);
+                double pOpen = pipe.GetCellPressure(0);
+                double pClosed = pipe.GetCellPressure(pipe.GetCellCount() - 1);
+                Console.WriteLine(
+                    $"t = {time * 1e3:F3} ms  Step {stepCount:D4}: " +
+                    $"sample = {sample:F3}, " +
+                    $"P_mid = {pMid:F2} Pa ({pMid / ambientPressure:F4} atm), " +
+                    $"P_open = {pOpen:F2} Pa, P_closed = {pClosed:F2} Pa");
+            }
+        }
+
+        public override void Draw(RenderWindow target)
+        {
+            float winWidth = target.GetView().Size.X;
+            float winHeight = target.GetView().Size.Y;
+
+            float pipeCenterY = winHeight / 2f;
+            float margin = 60f;
+            float pipeStartX = margin;
+            float pipeEndX = winWidth - margin;
+            float pipeLengthPx = pipeEndX - pipeStartX;
+            int n = pipe.GetCellCount();
+            float dx = pipeLengthPx / (n - 1);   // spacing between cell centres
+
+            float baseRadius = 25f;
+            float rangeFactor = 1f;
+            float scaleFactor = 5f;
+
+            // ----- smoothstep helper -----
+            static float SmoothStep(float edge0, float edge1, float x)
+            {
+                float t = Math.Clamp((x - edge0) / (edge1 - edge0), 0f, 1f);
+                return t * t * (3f - 2f * t);
+            }
+
+            // ----- Pre‑compute cell positions and radii -----
+            var centers = new float[n];
+            var radii = new float[n];
+            for (int i = 0; i < n; i++)
+            {
+                double p = pipe.GetCellPressure(i);
+                float deviation = (float)Math.Tanh((p - ambientPressure) / ambientPressure / rangeFactor);
+                radii[i] = baseRadius * (1f + deviation * scaleFactor);
+                if (radii[i] < 2f) radii[i] = 2f;
+                centers[i] = pipeStartX + i * dx;
+            }
+
+            // ----- Build triangle‑strip vertices -----
+            int segmentsPerCell = 8;   // smoothness
+            int totalPoints = n + (n - 1) * segmentsPerCell;
+            Vertex[] stripVertices = new Vertex[totalPoints * 2];   // top + bottom for each point
+            int idx = 0;
+
+            for (int i = 0; i < n; i++)
+            {
+                // ---- Cell centre ----
+                float x = centers[i];
+                float r = radii[i];
+                double p = pipe.GetCellPressure(i);
+                Color col = PressureColor(p);
+
+                stripVertices[idx++] = new Vertex(new Vector2f(x, pipeCenterY - r), col);
+                stripVertices[idx++] = new Vertex(new Vector2f(x, pipeCenterY + r), col);
+
+                // ---- Intermediate segments after this cell (if not last) ----
+                if (i < n - 1)
+                {
+                    for (int s = 1; s <= segmentsPerCell; s++)
+                    {
+                        float t = s / (float)segmentsPerCell;
+                        float st = SmoothStep(0f, 1f, t);
+                        float xi = centers[i] + (centers[i + 1] - centers[i]) * t;
+                        float ri = radii[i] + (radii[i + 1] - radii[i]) * st;
+                        double pi = pipe.GetCellPressure(i) * (1 - t) + pipe.GetCellPressure(i + 1) * t;
+                        Color coli = PressureColor(pi);
+
+                        stripVertices[idx++] = new Vertex(new Vector2f(xi, pipeCenterY - ri), coli);
+                        stripVertices[idx++] = new Vertex(new Vector2f(xi, pipeCenterY + ri), coli);
+                    }
+                }
+            }
+
+            // Draw the pipe as a triangle strip
+            var pipeMesh = new VertexArray(PrimitiveType.TriangleStrip, (uint)stripVertices.Length);
+            for (int i = 0; i < stripVertices.Length; i++)
+                pipeMesh[(uint)i] = stripVertices[i];
+            target.Draw(pipeMesh);
+
+            // ----- Closed end indicator (right) -----
+            float wallThickness = 8f;
+            var wall = new RectangleShape(new Vector2f(wallThickness, winHeight * 0.6f));
+            wall.Position = new Vector2f(pipeEndX, pipeCenterY - winHeight * 0.6f / 2f);
+            wall.FillColor = new Color(180, 180, 180);
+            target.Draw(wall);
+        }
+
+        /// <summary>Blue (low) → Green (ambient) → Red (high).</summary>
+        private Color PressureColor(double pressure)
+        {
+            double range = ambientPressure * 0.05;  // ±5% gives full colour swing
+            double t = (pressure - ambientPressure) / range;
+            t = Math.Clamp(t, -1.0, 1.0);
+
+            byte r, g, b;
+            if (t < 0)
+            {
+                double factor = -t;
+                r = 0;
+                g = (byte)(255 * (1 - factor));
+                b = (byte)(255 * factor);
+            }
+            else
+            {
+                double factor = t;
+                r = (byte)(255 * factor);
+                g = (byte)(255 * (1 - factor));
+                b = 0;
+            }
+            return new Color(r, g, b);
+        }
+    }
+}

Scenarios/Scenario.cs

@@ -0,0 +1,23 @@
+using SFML.Graphics;
+
+namespace FluidSim.Core
+{
+    public abstract class Scenario
+    {
+        /// <summary>
+        /// Initialize the scenario with a given audio sample rate.
+        /// </summary>
+        public abstract void Initialize(int sampleRate);
+
+        /// <summary>
+        /// Advance one simulation step and return an audio sample.
+        /// The step size is 1 / sampleRate seconds.
+        /// </summary>
+        public abstract float Process();
+
+        /// <summary>
+        /// Draw the current simulation state onto the given SFML render target.
+        /// </summary>
+        public abstract void Draw(RenderWindow target);
+    }
+}