抽奖转盘匀速开始停止，模拟摩擦力

公司要做一个转盘的抽奖，因为想让转盘像现实生活中的，慢慢加速慢慢减速，但是最后的减速还要确定目标位置，所以呢，抱起了高中的数学书

匀加速直线运动

百度百科：https://baike.baidu.com/item/%E5%8C%80%E5%8A%A0%E9%80%9F%E7%9B%B4%E7%BA%BF%E8%BF%90%E5%8A%A8

好吧，下面直接上代码，代码放unity里，直接把脚本挂到物体上，把转盘拖到wheel上，就能转动了，如果想改什么参数，具体的参数我都列出来了，看看注释

启动的话仔细看屏幕左上角，有一个输入框，表示转到第几个格子，格子索引从1开始

LuckyWheel.gif

   using UnityEngine;

    public class LuckyWheelDemo : MonoBehaviour {

    public Transform wheel;//转盘

    public bool isRun = false;//转盘是否在转动

    public float speedUpTime = 2;//用多久时间来加速

    public float highSpeedTime = 3;//在最高速运行多久

    public float maxSpeed = 500;//最高速

    public int areaCount = 8;//转盘一共多少个区域

    private float runTime;//转盘转动多久了

    private float curSpeed;//当前速度

    private float stopZ;//停止的Z轴坐标

    private float speedCutTime = 1;//减速时间

    private float lastFrameSpeed;//上一帧的速度

    private float acceleration;//加速度

    private bool isSpeedCut;//是否开始减速

    public string input;

    public void OnGUI()

    {

        input = GUILayout.TextField(input);

        if (GUILayout.Button("Rotate"))

        {

            RunWheel(int.Parse(input));

        }

    }

    /// 


    /// 运行转盘

    /// 

    /// 转到哪个格子

    public void RunWheel(int idx)

    {

        if (isRun) return;

        Init(idx);

    }

    /// 


    /// 获取目标格子的随机角度

    /// 

    /// 格子索引

    /// 

    public float GetRandomEndZ(int idx)

    {

        float areaAngle = 360f / areaCount;

        float endZ = areaAngle * idx;

        float offZ = UnityEngine.Random.Range(0.1f, areaAngle - 0.1f)-(areaAngle/2);

        return endZ + offZ;

    }

    /// 


    /// 设置减速时间和加速度

    /// 

    /// 当前转盘的Z角度

    public void SetSpeedCutTime(float curZ)

    {

        lastFrameSpeed = maxSpeed;

        float angle;

        if (curZ < stopZ)

            angle = curZ + 360 - stopZ + 360;

        else

            angle = curZ - stopZ + 360;

        speedCutTime = angle / (maxSpeed / 2);

        Debug.Log("角度："+angle+"    减速时间："+speedCutTime);

        acceleration = maxSpeed / speedCutTime;

    }

    /// 


    /// 初始化转盘数据

    /// 

    /// 转到哪个格子

    private void Init(int idx)

    {

        runTime = 0;

        speedCutTime = 1;

        isSpeedCut = false;

        stopZ = GetRandomEndZ(idx);

        isRun = true;

    }

    private void Update()

    {

        if (isRun)

        {

            if (runTime <= speedUpTime)//加速阶段

            {

                wheel.Rotate(Vector3.back * curSpeed * Time.deltaTime);

                runTime += Time.deltaTime;

                curSpeed = runTime / speedUpTime * maxSpeed;

            }

            else if (runTime <= speedUpTime + highSpeedTime)//全速转动阶段

            {

                wheel.Rotate(Vector3.back * maxSpeed * Time.deltaTime);

                runTime += Time.deltaTime;

            }

            else if (runTime <= speedUpTime + highSpeedTime + speedCutTime)//减速阶段

            {

                if (!isSpeedCut)//有没有初始化减速数据

                {

                    SetSpeedCutTime(wheel.localRotation.eulerAngles.z);

                    isSpeedCut = true;

                }

                float nowSpeed = maxSpeed - (runTime - speedUpTime - highSpeedTime)*acceleration;

                wheel.Rotate(Vector3.back*(nowSpeed+lastFrameSpeed)*0.5f*Time.deltaTime);

                lastFrameSpeed = nowSpeed;

                runTime += Time.deltaTime;

            }

            else//停止转动

            {

                isRun = false;

            }

        }

    }

}