Unity curve and elastic algorithm

                                      Unity curve and elastic algorithm

It is mainly used for recording, which can also be regarded as notes, so that you can get familiar with it later.

So go straight to the code.

//二阶曲线算法 
public static Vector3 Bezier(Vector3 start, Vector3 end, Vector3 tanPoint, float t)
 {
      Vector3 p0p1 = (1 - t) * start + t * tanPoint;
      Vector3 p1p2 = (1 - t) * tanPoint + t * end;
      Vector3 result = (1 - t) * p0p1 + t * p1p2;
      return result;
 }

 //三阶曲线算法
 public static Vector3 Interpolate(Vector3 start, Vector3 end, Vector3 tanPoint1, Vector3 tanPoint2, float t)
 {
      Vector3 position = (2.0f * t * t * t - 3.0f * t * t + 1.0f) * start
            + (t * t * t - 2.0f * t * t + t) * tanPoint1
            + (-2.0f * t * t * t + 3.0f * t * t) * end
            + (t * t * t - t * t) * tanPoint2;

      return position;
 }

Spring elastic algorithm

      F=kx elastic formula 

public class Spring
{
    // Spring simulation constants
    //质量
    private float mMass = 1f;
    //弹力系数 k
    private float mSpringConstant = 0.2f;
    //阻尼系数
    private float mDampingConstant = 0.92f;
    //静止位置
    private Vector2 mRestPos;

    // Spring simulation variables
    //速度
    private Vector2 mVelocity;
    //加速
    private float mAcceleration;
    //力
    private float mForce;

    //-------------------------------变量
    //临时位置
    public Vector2 mTempPos;
    //自身位置
    public Vector2 mSelfPos;

    /// <summary>
    /// 
    /// </summary>
    /// <param name="x">x 坐标</param>
    /// <param name="y">y 坐标</param>
    /// <param name="k">弹力系数</param>
    /// <param name="d">阻尼系数</param>
    /// <param name="m">质量</param>
    public Spring(float x, float y, float k, float d, float m)
    {
        mSelfPos = mTempPos = mRestPos = new Vector2(x, y);
        mSpringConstant = k;
        mDampingConstant = d;
        mMass = m;
    }

    public void OnUpdate()
    {
        mForce = -mSpringConstant * (mTempPos.x - mRestPos.x);          // f=-ky 弹力
        mAcceleration = mForce / mMass;                                 // Set the acceleration, f=ma == a=f/m 加速度
        mVelocity.x = mDampingConstant * (mVelocity.x + mAcceleration); // Set the velocity 速度
        mTempPos.x = mTempPos.x + mVelocity.x;                          // Updated position 

        mForce = -mSpringConstant * (mTempPos.y - mRestPos.y);          // f=-ky 弹力
        mAcceleration = mForce / mMass;                                 // Set the acceleration, f=ma == a=f/m 加速度
        mVelocity.y = mDampingConstant * (mVelocity.y + mAcceleration); // Set the velocity 速度
        mTempPos.y = mTempPos.y + mVelocity.y;                          // Updated position 
    }

	//根据鼠标移动偏移量 赋值一个x、y方向的弹力
    public void SetRestPos(float x, float y)
    {
        mRestPos = new Vector2(x, y);
    }

	//鼠标离开区域
    public void OnReleased()
    {
        if (mRestPos == mSelfPos) return;
        mRestPos = mSelfPos;
        //rest_posy = ypos;
    }

}

//根据曲线公式 循环得到一个精度为100个点的曲线
float pointStep = 1.0f / 100;
float t;
for (int i = 0; i < 100; i++)
{
    t = i * pointStep;
    mLineRenderer.SetPosition(i, BezierTool.Bezier(mStartPos, mEndPos, mControlPos, t));
}