unity sprite 淡入淡出速度

Question

我正在尝试统一循环播放精灵的淡入和淡出。我是 Unity 和 C# 的新手。

我当前的代码：

public float minimum = 0.0f;
public float maximum = 1f;
public float duration = 50.0f;

public bool faded = false;

private float startTime;
public SpriteRenderer sprite;

void Start () {
    startTime = Time.time;
}

void Update () {
    float t = (Time.time - startTime) / duration;

    if (faded) {
        sprite.color = new Color(1f, 1f, 1f, Mathf.SmoothStep(minimum, maximum, t));
        if (t > 1f) {
            faded = false;
            startTime = Time.time;
        }
    } else {
        sprite.color = new Color(1f, 1f, 1f, Mathf.SmoothStep(maximum, minimum, t));
        if (t > 1f) {
            faded = true;
            startTime = Time.time;
        }
    }
}

这可行，但太慢了，我希望让淡入更快，淡出比淡入慢一点。有点像心跳的效果。如何为此更新我的代码？

另外，有没有更好的方法呢？我认为Update() 上的NEW 太多会导致内存泄漏。

至于安德鲁给出的，我尝试调试他的代码：

    } else {
        sprite.color = new Color(1f, 1f, 1f, Mathf.Lerp(sprite.color.a, minimum, step));
        print (Mathf.Abs(sprite.color.a - minimum));
        print (threshold);

给我看：

 2.206551E-20 // Mathf.Abs()?
 1.401298E-45 // threshold?

Answer 1

不用担心Update()中的new，因为Color是值类型，而C#擅长处理垃圾回收

public float minimum = 0.0f;
public float maximum = 1f;
public float speed = 5.0f;
public float threshold = float.Epsilon;

public bool faded = false;

public SpriteRenderer sprite;

void Update () {
    float step = speed * Time.deltaTime;

    if (faded) {
        sprite.color = new Color(1f, 1f, 1f, Mathf.Lerp(sprite.color.a, maximum, step));
        if (Mathf.Abs(maximum - sprite.color.a) <= threshold)
            faded = false;

    } else {
        sprite.color = new Color(1f, 1f, 1f, Mathf.Lerp(sprite.color.a, minimum, step));
        if (Mathf.Abs(sprite.color.a - minimum) <= threshold)
            faded = true;
    }
}

另外，如果您只关心淡入淡出效果，您只需要一行：

public float max = 1f;
public float speed = 5.0f;

public SpriteRenderer sprite;

void Update () {
    sprite.color = new Color(1f, 1f, 1f, Mathf.PingPong(Time.time * speed, max));
}