using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace MathTest
{
    /// <summary>
    /// 3D向量类
    /// </summary>
    public class Vector3
    {
        public float x;
        public float y;
        public float z;

        public Vector3() { }

        public Vector3(Vector3 a)
        {
            x = a.x;
            y = a.y;
            z = a.z;
        }

        public Vector3(float x, float y, float z)
        {
            this.x = x;
            this.y = y;
            this.z = z;
        }

        //置为零向量
        public void Zero()
        {
            x = y = z = 0.0f;
        }

        //向量标准化
        public void Normalize()
        {
            float magSq = x * x + y * y + z * z;
            if (magSq > 0.0f) //检查除零
            {
                float oneOverMag = 1.0f / (float)Math.Sqrt(magSq);
                x *= oneOverMag;
                y *= oneOverMag;
                z *= oneOverMag;
            }
        }

        //重载"=="操作符
        public static bool operator ==(Vector3 a, Vector3 b)
        {
            return a.x == b.x && a.y == b.y && a.z == b.z;
        }

        //重载"!="操作符
        public static bool operator !=(Vector3 a, Vector3 b)
        {
            return a.x != b.x || a.y != b.y || a.z != b.z;
        }

        //重载二元"+"运算符
        public static Vector3 operator +(Vector3 a, Vector3 b)
        {
            return new Vector3(a.x + b.x, a.y + b.y, a.z + b.z);
        }

        //重载二元"-"运算符
        public static Vector3 operator -(Vector3 a, Vector3 b)
        {
            return new Vector3(a.x - b.x, a.y - b.y, a.z - b.z);
        }

        //重载一元"-"运算符
        public static Vector3 operator -(Vector3 a)
        {
            return new Vector3(-a.x, -a.y, -a.z);
        }

        //与标量的乘法
        public static Vector3 operator *(Vector3 a, float n)
        {
            return new Vector3(a.x * n, a.y * n, a.z * n);
        }

        //向量点乘
        public static Vector3 operator *(Vector3 a, Vector3 b)
        {
            return new Vector3(a.x * b.x, a.y * b.y, a.z * b.z);
        }

        //与标量的除法
        public static Vector3 operator /(Vector3 a, float n)
        {
            float oneOverN = 1.0f / n; //注意：这里不对“除零”进行检查
            return new Vector3(a.x * oneOverN, a.y * oneOverN, a.z * oneOverN);
        }

        //求向量模
        public float VectorMag()
        {
            return (float)Math.Sqrt(x * x + y * y + z * z);
        }

        //计算两向量的叉乘
        public static Vector3 CrossProduct(Vector3 a, Vector3 b)
        {
            return new Vector3(
                a.y * b.z - a.z * b.y,
                a.z * b.x - a.x * b.z,
                a.x * b.y - a.y * b.x
            );
        }

        //计算两点间的距离
        public static float Distance(Vector3 a, Vector3 b)
        {
            float dx = a.x - b.x;
            float dy = a.y - b.y;
            float dz = a.z - b.z;
            return (float)Math.Sqrt(dx * dx + dy * dy + dz * dz);
        }
    }
}