var raf;
  var arror = [];
  var running = false;
  //繪制圓形
  function createBall() {
    return {
      x: 0,
      y: 0,
      vx: 10-Math.random()*10,
      vy: 10-Math.random()*10,
      radius: 25,
      color:"red",
      draw: function() {
        ctx.beginPath();
        ctx.arc(this.x, this.y, this.radius, 0, Math.PI * 2, true);
        ctx.closePath();
        ctx.fillStyle = this.color;
        ctx.fill();
      }
    }
  }
  //繪制正方形
  function createSquare() {
    return {
      x: 0,
      y: 0,
      vx: 10-Math.random()*10,
      vy: 10-Math.random()*10,
      color:"red",
      draw: function() {
        ctx.beginPath();
        ctx.fillStyle = this.color;
        ctx.fillRect(this.x, this.y,30, 30);
        ctx.closePath();
      }
    }
  }
  //繪制五角星
  function createStar() {
    return {
      x: 0,
      y: 0,
      vx: 10-Math.random()*10,
      vy: 10-Math.random()*10,
      color:"red",
      draw: function() {
        ctx.font = "24px serif";
        ctx.textBaseline = "hanging";
        ctx.fillStyle=this.color;
        ctx.fillText("五角星",this.x, this.y);

      }
    }
  }
  //繪制三角形
  function createTriangle() {
    return {
      x: 0,
      y: 0,
      vx: 10-Math.random()*10,
      vy: 10-Math.random()*10,
      color:"red",
      draw: function() {
        ctx.beginPath();
        ctx.moveTo(this.x,this.y);
        ctx.lineTo(this.x+25,this.y+25);
        ctx.lineTo(this.x+25,this.y-25);
        ctx.fillStyle=this.color;
        ctx.fill();
      }
    }
  }
  //清除
  function clear() {
    ctx.fillStyle = 'rgba(255,255,255,0.3)';
    ctx.fillRect(0,0,canvas.width,canvas.height);
  }
　　　　//判斷圖形坐標是否超出畫布范圍
  function draw() {
    clear();
    arror.forEach(function(ball, i){
      ball.draw();
      ball.x += ball.vx;
      ball.y += ball.vy;
      if (ball.y + ball.vy > canvas.height || ball.y + ball.vy < 0) {
        ball.vy = -ball.vy;
      }
      if (ball.x + ball.vx > canvas.width || ball.x + ball.vx < 0) {
        ball.vx = -ball.vx;
      }
    });

    raf = window.requestAnimationFrame(draw);
  }
  canvas.addEventListener('click',function(e){
    if (!running) {
      raf = window.requestAnimationFrame(draw);
      running = true;
    }
    var colorarr=["#000000","#7F7F7F","#880015","#ED1C24","#FF7F27","#FFF200","#22B14C","#00A2E8","#3F48CC","#A349A4","#B97A57","#FFAEC9","#B5E61D"];
    var Graphics = ["Round","Square","Star","Triangle"];
    var typexz=Graphics[Math.floor(Math.random()*4)];
    var ball;
    switch(typexz){
      case "Round":
        ball = createBall();
        break;
      case "Square":
        ball = createSquare();
        break;
      case "Star":
        ball = createStar();
        break;
      case "Triangle":
        ball = createTriangle();
        break;
    }
    ball.x = e.clientX;
    ball.y = e.clientY;
    ball.color = colorarr[Math.floor(Math.random() * 10 + 3)];
    arror.push(ball);
  });
  draw();
 document.addEventListener('keydown',function (e) {
   if(e.keyCode==32){
     event.preventDefault();
     window.cancelAnimationFrame(raf);
     running = false;
   }
 })