Ray

struct

Properties	Description
direction	The direction of the ray.
origin	The origin point of the ray.

Constructors	Description
Ray	Creates a ray starting at origin along direction.

Public Methods	Description
GetPoint	Returns a point at distance units along the ray.
ToString	Returns a nicely formatted string for this ray.

RaycastHit

struct

Properties	Description
barycentricCoordinate	The barycentric coordinate of the triangle we hit.
collider	The Collider that was hit.
distance	The distance from the ray’s origin to the impact point.
lightmapCoord	The uv lightmap coordinate at the impact point.
normal	The normal of the surface the ray hit.
point	The impact point in world space where the ray hit the collider.
rigidbody	The Rigidbody of the collider that was hit. If the collider is not attached to a rigidbody then it is null.
textureCoord	The uv texture coordinate at the collision location.
textureCoord2	The secondary uv texture coordinate at the impact point.
transform	射线撞到的collider或者rigidbody所属物体的transform
triangleIndex	The index of the triangle that was hit.

Camera类中提供的用法

Ray 始终对应于视图中的一个点，因此 Camera 类提供 ScreenPointToRay 和 ViewportPointToRay函数。两者之间的区别在于 ScreenPointToRay 期望以像素坐标的形式提供该点，而 ViewportPointToRay 则接受0…1 范围内的标准化坐标（其中 0 表示视图的左下角，1 表示右上角）。这些函数中的每一个函数都返回由一个原点和一个矢量（该矢量显示从该原点出发的线条方向）组成的 Ray。
Ray源自近裁剪面而不是摄像机 (Camera) 的 transform.position 点。

1、通过鼠标位置点击场景中的物体，“这是一种基于对象在屏幕上的图像来定位对象的非常有用的方法。”

	public class ExampleScript : MonoBehaviour {
	    public Camera camera;
	    void Start(){
	        RaycastHit hit;
	        Ray ray = camera.ScreenPointToRay(Input.mousePosition);
	        if (Physics.Raycast(ray, out hit)) {
	            Transform objectHit = hit.transform;
	            // 对射线投射命中的对象执行一些操作。
	        }
	    }
	}

2、沿着射线移动相机

	public class ExampleScript : MonoBehaviour {
	    public bool zooming;
	    public float zoomSpeed;
	    public Camera camera;
	
	    void Update() {
	        if (zooming) {
	            Ray ray = camera.ScreenPointToRay(Input.mousePosition);
	            float zoomDistance = zoomSpeed * Input.GetAxis("Vertical") * Time.deltaTime;
	            camera.transform.Translate(ray.direction * zoomDistance, Space.World);
	        }
	    }
	}