// Learn TypeScript:
//  - [Chinese] https://docs.cocos.com/creator/manual/zh/scripting/typescript.html
//  - [English] http://www.cocos2d-x.org/docs/creator/manual/en/scripting/typescript.html
// Learn Attribute:
//  - [Chinese] https://docs.cocos.com/creator/manual/zh/scripting/reference/attributes.html
//  - [English] http://www.cocos2d-x.org/docs/creator/manual/en/scripting/reference/attributes.html
// Learn life-cycle callbacks:
//  - [Chinese] https://docs.cocos.com/creator/manual/zh/scripting/life-cycle-callbacks.html
//  - [English] http://www.cocos2d-x.org/docs/creator/manual/en/scripting/life-cycle-callbacks.html

export default class Vector2 {

    /**
     * 
     * @param posStart 插值运算
     * @param posEnd 
     * @param t 
     */
    public static lerp(posStart:cc.Vec2,posEnd:cc.Vec2,t:number):cc.Vec2
    {
        return this.bezierOne(t,posStart,posEnd);
    }

    //一次贝塞尔即为线性插值函数
    public static bezierOne(t:number,posStart:cc.Vec2,posEnd:cc.Vec2):cc.Vec2
    {
        
        if(t > 1)
        {
            t = 1;
        }else if(t < 0)
        {
            t = 0
        }
        
        //return posStart.addSelf(posEnd.subSelf(posStart).mulSelf(t));
        return posStart.mul(1 - t).add(posEnd.mul(t));

    }

    //二次贝塞尔曲线
    public static bezierTwo(t:number,posStart:cc.Vec2,posCon:cc.Vec2,posEnd:cc.Vec2):cc.Vec2
    {
        
        if(t > 1)
        {
            t = 1;
        }else if(t < 0)
        {
            t = 0
        }
        
        var n = (1 - t);
        var tt = t * t;

        var pos = posStart;

        pos.addSelf(posStart.mul(n * n));
        pos.addSelf(posCon.mul(2 * n * t));
        pos.addSelf(posEnd.mul(tt));

        return pos;
    }

    //三次贝塞尔
    public static bezierThree(t:number,posStart:cc.Vec2,posCon1:cc.Vec2,posCon2:cc.Vec2,posEnd:cc.Vec2):cc.Vec2
    {
        if(t > 1)
        {
            t = 1;
        }else if(t < 0)
        {
            t = 0
        }

        var n = (1 - t);
        var nn = n * n;
        var nnn = nn * n;
        var tt = t * t;
        var ttt = tt * t;

        var pos = posStart;
        pos.addSelf(posStart.mul(nnn));
        pos.addSelf(posCon1.mul(3*nn * t));
        pos.addSelf(posCon2.mul(3*n*tt));
        pos.addSelf(posEnd.mul(ttt));

        return pos;
    }

    public static distance(pos1:cc.Vec2,pos2:cc.Vec2):number
    {
        return pos2.sub(pos1).mag();
    }
    

}