function Interpolator(type) {
  this._i = type.func;
  this._snum = type.samples;
  this.s = [];  //Samples
};

Interpolator.prototype.addSample = function(sample){
  var p = this.s;
  p.push(sample);
  if(p.length > this._snum) p.shift();
};

Interpolator.prototype.getValue = function(t){
  return this._i(this.s, t);
};

Interpolator.Linear = {
  samples : 2,
  func : function(d,t){
    var v1 = d[0],
        v2 = d[1];

    if(!v2) return new Vector(0,0);

    var r1x = v1.x * (1-t),
        r1y = v1.y * (1-t),
        r2x = v2.x * t,
        r2y = v2.y * t

    return(new Vector(r1x+r2x,r1y+r2y));
  }
};

Interpolator.CatmullRom = {
  samples : 4,
  func : function(d,mu) {
    var v0 = d[0],
        v1 = d[1],
        v2 = d[2],
        v3 = d[3],
        a0,a1,a2,a3,mu2;

    if(!v0 || !v1 || !v2 || !v3 || !mu) return new Vector(0,0);

    mu2 = mu*mu;

    var a0x = -0.5 * v0.x + 1.5 * v1.x - 1.5 * v2.x + 0.5 * v3.x,
        a0y = -0.5 * v0.y + 1.5 * v1.y - 1.5 * v2.y + 0.5 * v3.y,
        a1x = v0.x - 2.5 * v1.x + 2 * v2.x - 0.5 * v3.x,
        a1y = v0.y - 2.5 * v1.y + 2 * v2.y - 0.5 * v3.y,
        a2x = -0.5 * v0.x + 0.5 * v2.x,
        a2y = -0.5 * v0.y + 0.5 * v2.y,
        a3x = v1.x,
        a3y = v1.y,

        rx = a0x * mu * mu2 + a1x * mu2 + a2x * mu + a3x,
        ry = a0y * mu * mu2 + a1y * mu2 + a2y * mu + a3y;

    return new Vector(rx,ry);
    }
  };

Interpolator.Hermite = {
  samples : 4,
  func : function(d,mu) {
    var v0 = d[0],
        v1 = d[1],
        v2 = d[2],
        v3 = d[3],
        bias = 0,
        tension = -0.3;

    if(!v0 || !v1 || !v2 || !v3 || !mu) return new Vector(0,0);

    var mu2 = mu * mu,
        mu3 = mu2 *mu,
        bbias = (1+bias),
        cbias = (1-bias),
        ten   = (1-tension),
        pb = bbias * ten / 2,
        nb = cbias * ten / 2;

    var m0x = (v1.x-v0.x) * pb,
        m0y = (v1.y-v0.y) * pb;

    m0x += (v2.x-v1.x) * nb;
    m0y += (v2.y-v1.y) * nb;

    var m1x = (v2.x-v1.x) * pb,
        m1y = (v2.y-v1.y) * pb;

    m1x += (v3.x-v2.x) * nb;
    m1y += (v3.y-v2.y) * nb;

    var a0 =  2*mu3 - 3*mu2 + 1,
        a1 =    mu3 - 2*mu2 + mu,
        a2 =    mu3 -   mu2,
        a3 = -2*mu3 + 3*mu2,

        rx = a0*v1.x + a1*m0x + a2*m1x + a3*v2.x,
        ry = a0*v1.y + a1*m0y + a2*m1y + a3*v2.y;

    return new Vector(rx,ry);
  }
};

Interpolator.Cubic = {
  samples : 4,
  func : function(d,mu) {
    var v0 = d[0],
        v1 = d[1],
        v2 = d[2],
        v3 = d[3];

    if(!v0 || !v1 || !v2 || !v3 || !mu) return new Vector(0,0);

    var mu2 = mu*mu,
        a0x = v3.x - v2.x - v0.x + v1.x,
        a0y = v3.y - v2.y - v0.y + v1.y,
        a1x = v0.x - v1.x - a0x,
        a1y = v0.y - v1.y - a0y,
        a2x = v2.x - v0.x,
        a2y = v2.y - v0.y,
        a3x = v1.x,
        a3y = v1.y,
        rx = a0x * mu * mu2 + a1x * mu2 + a2x * mu + a3x,
        ry = a0y * mu * mu2 + a1y * mu2 + a2y * mu + a3y;

    return new Vector(rx,ry);

  }
};