放大一定距离答案

【问题标题】：Zoom at a certain distance放大一定距离
【发布时间】：2019-09-15 15:03:57
【问题描述】：

我有以下 Unity 脚本

void Update()
{
    Ray mouseRay = Camera.main.ScreenPointToRay(Input.mousePosition);
    RaycastHit hit = new RaycastHit();

    if(Physics.Raycast(mouseRay, out hit))
    {
        if (Input.GetMouseButtonDown(0))
        {
            Camera.main.GetComponent<CameraController>().ZoomIn(hit.transform.position);
        }
    }
}

然后在我的相机里

public void ZoomIn(Vector3 target)
{
    zoomSavePosition = camera.transform.position;
    StartCoroutine(Zoom(zoomSavePosition, target, zoomDuration));
}


// ZoomRoutine
IEnumerator Zoom(Vector3 from, Vector3 to, float duration)
{
    float time = 0;
    Quaternion rotation = camera.transform.rotation;
    Quaternion targetRotation = Quaternion.LookRotation(to - camera.transform.position);
    while (time < zoomDuration)
    {
        camera.transform.position = Vector3.Lerp(from, to, time / zoomDuration);
        camera.transform.rotation = Quaternion.Slerp(rotation, targetRotation, time / zoomDuration);

        time += TimeManager.instance.deltaTime;
        yield return null;
    }

    camera.transform.position = to;
    camera.transform.rotation = targetRotation;
}

这很好用，但它会放大对象内部。我想，无论从哪里到哪里，我总是缩放并最终与目标保持相同的距离。

我正在考虑使用MoveTowards，但是在协程内部这会使运动停止，但旋转会继续进行（而且很丑）

所以给一个点 A 和一个点 B 我如何计算中间的距离，它设置为与 B 的距离始终相同？

【问题讨论】：

标签： c# unity3d math

【解决方案1】：

要缩放到距目标对象的特定距离，您需要计算与目标对象在相机方向上的距离，然后将其减去目标位置。

var heading = to - from;
var dist = heading.magnitude;
var direction = heading / dist;

Vector3 newTargetPosition = to - (direction * distance);

参考：https://docs.unity3d.com/Manual/DirectionDistanceFromOneObjectToAnother.html

通过此调整，您可以停止缩放到任何提供的距离。调整后的代码如下所示：

public void ZoomIn(Vector3 target)
{
    float targetDistance = 2f;
    zoomSavePosition = camera.transform.position;
    StartCoroutine(Zoom(zoomSavePosition, target, zoomDuration, targetDistance));
}


// ZoomRoutine
IEnumerator Zoom(Vector3 from, Vector3 to, float duration, float distance)
{
    float time = 0;
    Quaternion rotation = camera.transform.rotation;
    Quaternion targetRotation = Quaternion.LookRotation(to - camera.transform.position);

    var heading = to - from;
    var dist = heading.magnitude;
    var direction = heading / dist;

    Vector3 newTargetPosition = to - (direction * distance);

    while (time < zoomDuration)
    {
        camera.transform.position = Vector3.Lerp(from, newTargetPosition, time / zoomDuration);
        camera.transform.rotation = Quaternion.Slerp(rotation, targetRotation, time / zoomDuration);

        time += Time.deltaTime;
        yield return null;
    }

    camera.transform.position = newTargetPosition;
    camera.transform.rotation = targetRotation;
}

您可以在要停止缩放的位置设置 targetDistance 的值。

【讨论】：