简单记录下点乘叉乘，要不每次用完就忘，忘了又查。

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

public class TestCrossDot : MonoBehaviour
{

    /// <summary>
    /// 原点
    /// </summary>
    public Transform tfOrign;
    /// <summary>
    /// 物体1
    /// </summary>
    public Transform tf1;
    /// <summary>
    /// 物体2
    /// </summary>
    public Transform tf2;


    // Update is called once per frame
    void Update()
    {
        Vector3 v3From = tf1.position - tfOrign.position;
        Vector3 v3To = tf2.position - tfOrign.position;
        //计算叉乘，y小于0在左，y大于0在右
        Vector3 cross = Vector3.Cross(v3From, v3To);
        //计算点乘，通向大于0，对向小于0
        float dot = Vector3.Dot(v3From, v3To);

        Debug.Log("cross=" + cross + "   dot=" + dot);
        //计算两个向量夹角
        float angle = Vector3.Angle(v3From, v3To);
        //转换为0~360范围
        if (cross.y > 0)
        {
            angle = 360 - angle;
        }
        Debug.Log("angle=" + angle);
    }


}