[游戏开发]解决Unity3D中ScreenPointToRay不准确的问题

一、问题

1.我在场景里使用了两个相机。主相机渲染UGUI；另一个相机（透视）渲染模型，使用Render Texture将画面嵌入到UI中。
2.模型添加了Mesh Collider，使用射线检测点击事件。
3.实际点击位置和预计点击位置不一致。

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二、解决

 展开相机的参数，逐个分析了一波，一个叫Sensor Size（传感器尺寸）的参数进入了我的视野。下面是关键代码：

//使用RT的物理相机
float f = rayCamera.sensorSize.y == 0 ? 1 : rayCamera.sensorSize.x / rayCamera.sensorSize.y;//防止除以0
ray = rayCamera.ScreenPointToRay(Input.mousePosition * f);

三、话不多说，上代码

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class Click3D : MonoBehaviour
{
    [Header("发出射线的相机")]
    public Camera rayCamera;
    [Header("射线检测的层级")]
    public string rayLayer = "Model";
    [Header("被点击到的物体位移")]
    public Vector3 colliderMove = Vector3.up;
    [Header("是否为本地坐标")]
    public bool isLocalCoordinate = false;
    private bool isDirectRender = false;//相机是否直接渲染
    private Collider[] colliders;//点击的碰撞体
    private Vector3[] collidersPosition;//碰撞体位置
    private Ray ray;//射线
    private RaycastHit raycastHit;//射线信息
    private RaycastHit[] raycastHits;//射线信息
    private int currentColliderIndex = -1;
    
    // Start is called before the first frame update
    void Start()
    {
        isDirectRender = rayCamera.targetTexture == null;
        colliders = GetComponentsInChildren<Collider>();
        collidersPosition = new Vector3[colliders.Length];
        for (int i = 0; i < colliders.Length; i++)
        {
            collidersPosition[i] = isLocalCoordinate ? colliders[i].transform.localPosition : colliders[i].transform.position;
        }
    }

    // Update is called once per frame
    void Update()
    {
        MouseClick();
    }

    /// <summary>
    /// 鼠标点击
    /// </summary>
    private void MouseClick()
    {
        if (Input.GetMouseButtonDown(0))
        {
            GameObject go = RayCheckSingle();
    
            if (go != null)
            {
                OnClick(go.name);
            }
        }
    }
    /// <summary>
    /// 点击响应
    /// </summary>
    /// <param name="clickName"></param>
    public void OnClick(string clickName)
    {
        for (int i = 0; i < colliders.Length; i++)
        {
            bool isClick = clickName.Equals(colliders[i].name);
            if (isClick)
            {
                if (isLocalCoordinate)
                {
                    colliders[i].transform.localPosition = currentColliderIndex != i ? collidersPosition[i] + colliderMove : collidersPosition[i];
                }
                else
                {
                    colliders[i].transform.position = currentColliderIndex != i ? collidersPosition[i] + colliderMove : collidersPosition[i];
                }
                currentColliderIndex = i;
            }
            else
            {
                if (isLocalCoordinate)
                {
                    colliders[i].transform.localPosition = collidersPosition[i];
                }
                else
                {
                    colliders[i].transform.position = collidersPosition[i];
                }
            }
        }
    }
    /// <summary>
    /// 射线检测单个物体
    /// </summary>
    private GameObject RayCheckSingle()
    {
        if (isDirectRender)
        {
            ray = rayCamera.ScreenPointToRay(Input.mousePosition);
        }
        else
        {
            float f = rayCamera.sensorSize.y == 0 ? 1 : rayCamera.sensorSize.x / rayCamera.sensorSize.y;//防止除以0
            ray = rayCamera.ScreenPointToRay(Input.mousePosition * f);
        }
        //Debug射线
        //Debug.DrawLine(ray.origin, ray.origin + ray.direction * 1000, Color.yellow,10);
        if (Physics.Raycast(ray,out raycastHit,rayCamera.farClipPlane,1 << LayerMask.NameToLayer(rayLayer)))
        {
            return raycastHit.collider.gameObject;
        }
        return null;
    }
    /// <summary>
    /// 射线检测多个物体
    /// </summary>
    private GameObject[] RayCheckMulti()
    {
        if (isDirectRender)
        {
            ray = rayCamera.ScreenPointToRay(Input.mousePosition);
        }
        else
        {
            float f = rayCamera.sensorSize.y == 0 ? 1 : rayCamera.sensorSize.x / rayCamera.sensorSize.y;//防止除以0
            ray = rayCamera.ScreenPointToRay(Input.mousePosition * f);
        }
        raycastHits = Physics.RaycastAll(ray, rayCamera.farClipPlane, 1 << LayerMask.NameToLayer(rayLayer));
        
        if (raycastHits.Length > 0)
        {
            GameObject[] hitGOs = new GameObject[raycastHits.Length];
            for (int i = 0; i < raycastHits.Length; i++)
            {
                hitGOs[i] = raycastHits[i].collider.gameObject;
            }
            return hitGOs;
        }
        return null;
    }
}