Unity：Camra相机

1. 将屏幕坐标转换成世界坐标

Camera.main.ScreenToWorldPoint(Input.mousePosition);   X    //将鼠标点击的坐标转换成世界坐标

注意：该输出为一个固定坐标，转换失败。因为mousePosition是屏幕坐标（x,y,0），z轴是点与相机的距离。

public class Move : MonoBehaviour
{
    private Vector3 offset;  //加一个偏移量，操作更丝滑
    private void OnMouseDown()
    {
        float sreenZ = Camera.main.WorldToScreenPoint(transform.position).z;
        offset = transform.position - Camera.main.ScreenToWorldPoint(new Vector3(Input.mousePosition.x, Input.mousePosition.y, sreenZ));
    }
    private void OnMouseDrag()
    {
        Vector3 screenPos = Input.mousePosition;
        float screenZ = Camera.main.WorldToScreenPoint(transform.position).z;
        transform.position = Camera.main.ScreenToWorldPoint(new Vector3(screenPos.x, screenPos.y, screenZ)) + offset;
    }
}

2. 将屏幕坐标转换成射线

Ray ray = Camera.main.ScreenPointToRay(Input.mousePosition)  //使用主相机创建一条射线，射线方向是鼠标点击的位置

案例1. 2D场景相机跟随（相机会跟随人物上下左右移动）

    //相机跟随的速度
    private float speedX = 2;  
    private float speedY = 5;
    //人物与相机距离多少时开始移动
    private float distance = 1; 
    //移动边界限制
    private float minPosX = -2.5f;  
    private float maxPosX = 2.5f;
    private float minPosY = -2.5f;
    private float maxPosY = 2.5f;
    private void Update()
    {
        float disX = player.position.x - transform.position.x;
        float disY = player.position.y - transform.position.y;
        if (disX > distance)
        {
            transform.position = new Vector3(transform.position.x + speedX * Time.deltaTime, transform.position.y, transform.position.z);
        }
        if (disX < -distance)
        {
            transform.position = new Vector3(transform.position.x - speedX * Time.deltaTime, transform.position.y, transform.position.z);
        }
        //限制移动区域
        float realPosX = Mathf.Clamp(transform.position.x, minPosX, maxPosX);
        if (disY > distance)
        {
            transform.position = new Vector3(realPosX, transform.position.y + speedY * Time.deltaTime, transform.position.z);
        }
        if (disY < -distance)
        {
            transform.position = new Vector3(realPosX, transform.position.y - speedY * Time.deltaTime, transform.position.z);
        }
        float realPosY = Mathf.Clamp(transform.position.y, minPosY, maxPosY);
        transform.position = new Vector3(realPosX, realPosY, transform.position.z);
    }

案例2. 3D场景相机跟随（角色被挡住，相机滑动到能看到角色位置）

通过代码设置观察点，找到能看见目标的观察点

通过Cinemachine制作

直接把相机移到遮挡处遮挡物变透明

案例3. 添加小地图

1.将相机看到的内容渲染到一张图上(小地图同步)

1）新建一个材质Render Texture

2）将材质放在相机Target Texture上

3）新建一个UI-->Raw Image

4）将材质放在Raw Image --> Texture上

5）在Scene视角里调整好小窗口的位置

6）复制一个相机，去掉Target Texture里的材质

最终实现效果：