如何在一定时间内延长对角线渲染线

Question

我通过将以下脚本附加到一个空的游戏对象来创建了一个对角线渲染器。如何将两端的线延长一半长度，以及如何将线沿 x 轴延长 1 个单位？两者都在一段时间内。

public class DiagonalLine : MonoBehaviour {

bool firstLineComplete = false;
LineRenderer diagLine;

public Vector3 startPoint = new Vector3 (0, 0, 0);
public Vector3 endPoint = new Vector3 (1.0f, 1.0f, 0);

public float lineDrawSpeed;
// Use this for initialization
void Start () {

    diagLine = gameObject.AddComponent<LineRenderer>();
    diagLine.material = new Material (Shader.Find ("Sprites/Default"));
    diagLine.startColor = diagLine.endColor = Color.green;
    diagLine.startWidth = diagLine.endWidth = 0.15f;

    diagLine.SetPosition (0, startPoint);
    diagLine.SetPosition (1, endPoint);

    }
}

Answer 1

把你的问题分解成几部分：

1.将线两边延长x个单位：

这是通过Ray 类完成的。从startPoint 和endPoint 变量创建一个新的Ray 实例，然后使用Ray.GetPoint 函数扩展该行。您必须在两边都这样做才能获得新的延长线。

Ray 类的简单包装器以简化此操作：

Vector3 extendLine(Vector3 startPoint, Vector3 endPoint, ExtendDirection extendDirection, float extendDistance)
{
    Ray ray = new Ray();

    //Start
    if (extendDirection == ExtendDirection.START_POINT)
    {
        ray.origin = startPoint;
        ray.direction = startPoint - endPoint;
    }

    //End
    else if (extendDirection == ExtendDirection.END_POINT)
    {
        ray.origin = endPoint;
        ray.direction = endPoint - startPoint;
    }

    //Extend
    Vector3 newUnityPoint = ray.GetPoint(extendDistance);
    //Debug.DrawLine(ray.origin, newUnityPoint, Color.blue);
    return newUnityPoint;
}

public enum ExtendDirection
{
    START_POINT, END_POINT
}

向左延伸

Vector3 newStartPos = extendLine(startPoint, endPoint, ExtendDirection.START_POINT, 4);
diagLine.SetPosition(0, newStartPos);

延伸到右端

Vector3 newEndPos = extendLine(startPoint, endPoint, ExtendDirection.END_POINT, 4);
diagLine.SetPosition(1, newEndPos);

---

2。要随时间动画/移动它，请使用协程和Time.deltaTime。每帧使用Time.deltaTime 增加一个变量，然后使用Vector3.Lerp 来处理from 和to 值。

例如参见this 函数。

将两者结合起来，以下是随着时间的推移扩展两条线的完整功能：

bool isRunning = false;

IEnumerator extentLineOverTime(LineRenderer targetLineRenderer, float extendDistance, float duration)
{
    //Calculate Left from extension length
    Vector3 fromValLeftPos = targetLineRenderer.GetPosition(0);
    //Calculate Right from extension length
    Vector3 fromValRightPos = targetLineRenderer.GetPosition(1);

    //Calculate Left to extension length
    Vector3 newLeftPos = extendLine(fromValLeftPos, fromValRightPos, ExtendDirection.START_POINT, extendDistance);
    //Calculate Right to extension length
    Vector3 newRightPos = extendLine(fromValLeftPos, fromValRightPos, ExtendDirection.END_POINT, extendDistance);

    //Make sure there is only one instance of this function running
    if (isRunning)
    {
        yield break; ///exit if this is still running
    }
    isRunning = true;

    float counter = 0;


    while (counter < duration)
    {
        counter += Time.deltaTime;

        //Move to left overtime
        Vector3 tempLeftPos = Vector3.Lerp(fromValLeftPos, newLeftPos, counter / duration);
        targetLineRenderer.SetPosition(0, tempLeftPos);

        //Move to Right overtime
        Vector3 tempRightPos = Vector3.Lerp(fromValRightPos, newRightPos, counter / duration);
        targetLineRenderer.SetPosition(1, tempRightPos);

        yield return null;
    }
    isRunning = false;
}

---

用法：

LineRenderer diagLine;

public Vector3 startPoint = new Vector3(0, 0, 0);
public Vector3 endPoint = new Vector3(1.0f, 1.0f, 0);

// Use this for initialization
void Start()
{
    diagLine = gameObject.AddComponent<LineRenderer>();
    diagLine.material = new Material(Shader.Find("Sprites/Default"));
    diagLine.startColor = diagLine.endColor = Color.green;
    diagLine.startWidth = diagLine.endWidth = 0.15f;

    diagLine.SetPosition(0, startPoint);
    diagLine.SetPosition(1, endPoint);

    //Extend Line Over time
    StartCoroutine(extentLineOverTime(diagLine, 4, 3));
}

StartCoroutine(extentLineOverTime(diagLine, 4, 3)); 将在 3 秒内将线从两侧延长 4 个单位。

Answer 2

这是基本的向量数学。

你有一行（从头到尾）：

 Vector3 v = start - end;

然后你将每一边都延长一半，如果它：

 extensionA = start + (v * 0.5f);
 extensionB = end + (v * -0.5f);

如果需要扩展 1 则归一化：

 Vector3 v = (start - end).normalized;
 extensionA = start + v;
 extensionB = end + (v * -1f);