今日更新總結：Unity 2D 粒子模擬系統全面優化

一、模組化重構

1. 拆分核心腳本

   • ParticleManager.cs：物件池化管理粒子與標籤

   • GravitationalSystem.cs：萬有引力、合併／分裂邏輯

   • EnergyTracker.cs：動能統計與能量柱圖顯示

   • SimulationUIBindings.cs：延遲啟動與 UI 控制

   • LogExporter.cs：粒子狀態與碰撞事件日誌輸出

   • SimulationController.cs：流程調度、暫停／重置／倍率控制

2. 延遲啟動

    // SimulationController.cs
    private bool hasStarted = false;
   
    public void StartSimulation()
    {
        if (hasStarted) return;
        hasStarted = true;
        // 初始化模組…
        GenerateParticlesFromInput();
        StartCoroutine(LogLoop());
    }
   
    private void Update()
    {
        if (!hasStarted || isPaused) return;
        // 模擬邏輯…
    }
   

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二、效能優化五部曲

1. 物理計算節流

// SimulationController.cs
private int physicsFrameCounter = 0;
public int physicsFrameThreshold = 2; // 每兩幀執行一次

private void FixedUpdate()
{
    if (!hasStarted || isPaused) return;
    if (++physicsFrameCounter % physicsFrameThreshold == 0)
        gravitationalSystem.ApplyForces();
}

2. 全面物件池化

// ParticleManager.cs (節錄)
private Queue<GameObject> particlePool = new();
private Queue<TMP_Text>    labelPool    = new();

private void Awake()
{
    for (int i = 0; i < initialParticlePoolSize; i++)
    {
        var p = Instantiate(particlePrefab, transform);
        p.SetActive(false);
        particlePool.Enqueue(p);
    }
    // 標籤池同理…
}

public void CreateParticle(Vector2 pos, Vector2 vel, float mass)
{
    var p   = particlePool.Count>0 ? particlePool.Dequeue() : Instantiate(particlePrefab, transform);
    p.SetActive(true);
    // 設定 Rigidbody2D、顏色、大小…
    var lbl = labelPool.Count>0 ? labelPool.Dequeue() : Instantiate(labelPrefab, worldCanvas.transform).GetComponent<TMP_Text>();
    lbl.gameObject.SetActive(true);
    // 註冊到 activeParticles / activeLabels…
}

3. GC 分配優化

// LogExporter.cs (節錄)
private StringBuilder sbScreen = new();
private StringBuilder sbFile   = new();

public void LogParticleStates()
{
    sbScreen.Clear();
    sbFile.Clear();
    float t = Time.time;
    foreach (var p in particleManager.GetActiveParticles())
    {
        // AppendLine 到 sbScreen / sbFile…
    }
    logOutputText.text = sbScreen.ToString();
    File.AppendAllText(logFilePath, sbFile.ToString());
    // collisionLog…
}

4. 尾部交換移除法

// ParticleManager.cs (節錄)
public void RemoveParticle(int idx)
{
    int last = activeParticles.Count - 1;
    if (idx < 0 || idx > last) return;
    var p   = activeParticles[idx];
    var lbl = activeLabels   [idx];
    // 回收到池…
    if (idx != last)
    {
        activeParticles[idx] = activeParticles[last];
        activeLabels  [idx] = activeLabels  [last];
    }
    activeParticles.RemoveAt(last);
    activeLabels  .RemoveAt(last);
}

5. Coroutine 定時更新

// EnergyTracker.cs
private IEnumerator EnergyLoop()
{
    while (true)
    {
        yield return new WaitForSeconds(energyLogInterval);
        LogTotalKineticEnergy();
    }
}

private void Start()
{
    StartCoroutine(EnergyLoop());
}

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三、UI 顯示控制

• 開始前：只顯示「粒子數量輸入框」「速度輸入框」「開始按鈕」。

• 按下開始：隱藏初始輸入欄，顯示完整控制面板（暫停、重置、速度滑桿、能量圖、日誌等）。

• 重置：清除所有粒子與標籤，重新顯示開始按鈕。

// SimulationUIBindings.cs (節錄)
public GameObject[] uiHideOnStart;
public GameObject[] uiShowAfterStart;

startButton.onClick.AddListener(()=>
{
    controller.StartSimulation();
    foreach(var go in uiHideOnStart) go.SetActive(false);
    foreach(var go in uiShowAfterStart) go.SetActive(true);
    startButton.gameObject.SetActive(false);
});

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