coa4u/src/ActionsInterval/ActionBezierRel.cs

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

class ActionBezierRel : ActionInterval
{
    protected Vector3 ep;
    protected Vector3 cp1;
    protected Vector3 cp2;
    protected Vector3 startPoint;
    protected Vector3 endPoint;
    protected Vector3 startControlPoint;
    protected Vector3 endControlPoint;

    public ActionBezierRel(Vector3 tgtSCP, Vector3 tgtECP, Vector3 tgtEnd, float tgtDuration)
        : base(tgtDuration)
    {
        ep = tgtEnd;
        cp1 = tgtSCP;
        cp2 = tgtECP;
    }

    public override Action clone()
    {
        return new ActionBezierRel(startControlPoint, endControlPoint, endPoint, duration);
    }

    public override Action reverse()
    {
        return new ActionBezierRel(-startControlPoint, -endControlPoint, -endPoint, duration);
    }

    public override void start()
    {
        base.start();
        startPoint = target.transform.position;
        endPoint = startPoint + ep;
        startControlPoint = startPoint + cp1;
        endControlPoint = startControlPoint + cp2;
    }

    public override void stepInterval(float dt)
    {
        float t = timer / duration;
        Vector3 newPosition = (((-startPoint
            + 3 * (startControlPoint - endControlPoint) + endPoint) * t
            + (3 * (startPoint + endControlPoint) - 6 * startControlPoint)) * t +
            3 * (startControlPoint - startPoint)) * t + startPoint;
        transform.position = newPosition;
    }
}