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如何使用canvad实现粒子运动效果?

2018-03-06 08:01:01 来源:www.cvmachine.com 【

如何使用canvad实现粒子运动效果?

没有最好,只有更好,如题所示,这篇文章只要是分享一个用 Canvas 来实现的粒子运动效果。感觉有点标题党了,但换个角度,勉勉强强算是炫丽吧,虽然色彩上与炫丽无关,但运动效果上还是算得上有点点炫的。不管怎么样,我们还是开始这个所谓的炫丽效果吧!

直接上代码 ,不懂可以看代码注释。估计就会看明白大概的思路了。

html 代码

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Canvas 实现炫丽的粒子运动效果-云库前端</title>
<style>
* {
  margin: 0;
  padding: 0;
}
html,
body {
  width: 100%;
  height: 100%;
}
canvas {
  display: block;
  background: #000;
}
body::-webkit-scrollbar{
  display: none;
}
.operator-box{
  position: fixed;
  top: 0;
  left: 50%;
  border: 1px solid #fff;
  background: rgba(255,255,255,0.5);
  padding: 20px 10px;
  -webkit-transform: translateX(-50%);
  transform: translateX(-50%);
}
.back-type,.back-animate{
  margin-right: 20px;
}
.flex-box{
  display: flex;
  justify-content: center;
  align-items: center;
}
#input-text{
  line-height: 35px;
  width: 260px;
  height: 35px;
  background: rgba(0, 0, 0,0.7);
  color: #fff;
  font-size: 16px;
  border: none;
  outline: none;
  text-indent: 12px;
  box-shadow: inset 0 0 12px 1px rgba(0,0,0,0.7);
}
#input-text::placeholder{
  color: #ccc;
  line-height: 55px;
  height: 55px;
}
select{
  -webkit-appearance: none;
  -moz-appearance: none;
  appearance: none;
  border: none;
  padding: 0px 20px 0px 6px;
  height: 35px;
  color: #fff;
  text-align: left;
  background: rgba(0, 0, 0,0.7) url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAUAAAAICAYAAAAx8TU7AAAAOUlEQ…R4gPgWEIMAiOYBCS4C8ZDAIrBq4gigNkztQEFMi6AuQHESAPMeXiEMiWfpAAAAAElFTkSuQmCC) no-repeat 190px 12px;
  background-size: 5px 8px;
  box-shadow: inset 0 0 12px 1px rgba(0,0,0,0.7);
}
</style>
</head>
<body>
<div class="operator-box">
<div class="flex-box">
  <div class="back-type">散开类型:
    <select name="" id="selectType">
      <option value="back">归位</option>
      <option value="auto">随机</option>
    </select>
  </div>
  <div class="back-animate">散开效果(对归位有效):
    <select class="back-dynamics" id="selectDynamics">
      <option value="spring">dynamics.spring</option>
      <option value="bounce">dynamics.bounce</option>
      <option value="forceWithGravity">dynamics.forceWithGravity</option>
      <option value="gravity">dynamics.gravity</option>
      <option value="easeInOut">dynamics.easeInOut</option>
      <option value="easeIn">dynamics.easeIn</option>
      <option value="easeOut">dynamics.easeOut</option>
      <option value="linear">dynamics.linear</option>
    </select>
  </div>
  <div class="input-box"><input type="text" placeholder="输入汉字后回车" id="input-text"></div>
</div>
</div>
<script src="dynamics.min.js"></script>
<script src="index.js"></script>
<script>
var iCircle = new Circle();
</script>
</body>
</html>

HTML 代码不多,只要是几个操作元素。这里一看就明白。不费过多口舌。我们来看看本文的主角 JavaScript 代码,不过,在看代码前,我们不妨先听听实现这个效果的思路:

  1. 首先,我们得先生成一堆群众演员(粒子);
  2. 把每个粒子的相关参数挂到自身的一些属性上,因为第个粒子都会有自己的运动轨迹;
  3. 接着得让它们各自运动起来。运动有两种(自由运动和生成文字的运动);

JavaScript 代码中使用了三个 Canvas 画布,this.iCanvas(主场)、this.iCanvasCalculate(用来计算文字宽度)、this.iCanvasPixel(用于画出文字,并从中得到文字对应的像素点的位置坐标)。

this.iCanvasCalculate 和 this.iCanvasPixel 这两个无需在页面中显示出来,只是辅助作用。

下面就献上棒棒的 JS 实现代码

function Circle() {
  var This = this;
  this.init();
  this.generalRandomParam();
  this.drawCircles();
  this.ballAnimate();
  this.getUserText();
  // 窗口改变大小后,生计算并获取画面
  window.onresize = function(){
    This.stateW = document.body.offsetWidth;
    This.stateH = document.body.offsetHeight;
    This.iCanvasW = This.iCanvas.width = This.stateW;
    This.iCanvasH = This.iCanvas.height = This.stateH;
    This.ctx = This.iCanvas.getContext("2d");
  }
}
// 初始化
Circle.prototype.init = function(){
  //父元素宽高
  this.stateW = document.body.offsetWidth;
  this.stateH = document.body.offsetHeight;
  this.iCanvas = document.createElement("canvas");
  // 设置Canvas 与父元素同宽高
  this.iCanvasW = this.iCanvas.width = this.stateW;
  this.iCanvasH = this.iCanvas.height = this.stateH;
  // 获取 2d 绘画环境
  this.ctx = this.iCanvas.getContext("2d");
  // 插入到 body 元素中
  document.body.appendChild(this.iCanvas);
  this.iCanvasCalculate = document.createElement("canvas");
  // 用于保存计算文字宽度的画布
  this.mCtx = this.iCanvasCalculate.getContext("2d");
  this.mCtx.font = "128px 微软雅黑";
  this.iCanvasPixel = document.createElement("canvas");
  this.iCanvasPixel.setAttribute("style","position:absolute;top:0;left:0;");
  this.pCtx = null; // 用于绘画文字的画布
  // 随机生成圆的数量
  this.ballNumber = ramdomNumber(1000, 2000);
  // 保存所有小球的数组
  this.balls = [];
  // 保存动画中最后一个停止运动的小球
  this.animte = null;
  this.imageData = null;
  this.textWidth = 0; // 保存生成文字的宽度
  this.textHeight = 150; // 保存生成文字的高度
  this.inputText = ""; // 保存用户输入的内容
  this.actionCount = 0;
  this.ballActor = []; // 保存生成文字的粒子
  this.actorNumber = 0; // 保存生成文字的粒子数量
  this.backType = "back"; // 归位
  this.backDynamics = ""; // 动画效果
  this.isPlay = false; // 标识(在生成文字过程中,不能再生成)
}
// 渲染出所有圆
Circle.prototype.drawCircles = function () {
  for(var i=0;i<this.ballNumber;i++){
    this.renderBall(this.balls[0]);
  }
}
// 获取用户输入文字
Circle.prototype.getUserText = function(){
  This = this; // 保存 this 指向
  ipu = document.getElementById("input-text");
  ipu.addEventListener("keydown",function(event){
    if(event.which === 13){ // 如果是回车键
      ipu.value = ipu.value.trim(); // 去头尾空格
      var pat = /[\u4e00-\u9fa5]/; // 中文判断
      var isChinese = pat.test(ipu.value);
      if(ipu.value.length !=0 && isChinese){
        This.inputText = ipu.value;
      }else{
        alert("请输入汉字");
        return;
      }
      if(This.isPlay){
        return
      }
      This.getAnimateType();
      This.getTextPixel();
      This.isPlay = true;
    }
  });
}
// 计算文字的宽
Circle.prototype.calculateTextWidth = function () {
  this.textWidth = this.mCtx.measureText(this.inputText).width;
}
// 获取文字像素点
Circle.prototype.getTextPixel = function () {
  if(this.pCtx){
    this.pCtx.clearRect(0,0,this.textWidth,this.textHeight);
  }
  this.calculateTextWidth(this.inputText);
  this.iCanvasPixel.width = this.textWidth;
  this.iCanvasPixel.height = this.textHeight;
  this.pCtx = this.iCanvasPixel.getContext("2d");
  this.pCtx.font = "128px 微软雅黑";
  this.pCtx.fillStyle = "#FF0000";
  this.pCtx.textBaseline = "botom";
  this.pCtx.fillText(this.inputText,0,110);
  this.imageData = this.pCtx.getImageData(0,0,this.textWidth,this.textHeight).data;
  this.getTextPixelPosition(this.textWidth,this.textHeight);
}
// 获取文字粒子像素点位置
Circle.prototype.getTextPixelPosition = function (width,height) {
  var left = (this.iCanvasW - width)/2;
  var top = (this.iCanvasH - height)/2;
  var space = 4;
  this.actionCount = 0;
  for(var i=0;i<this.textHeight;i+=space){
    for(var j=0;j<this.textWidth;j+=space){
      var index = j*space+i*this.textWidth*4;
      if(this.imageData[index] == 255){
        if(this.actionCount<this.ballNumber){
          this.balls[this.actionCount].status = 1;
          this.balls[this.actionCount].targetX = left+j;
          this.balls[this.actionCount].targetY = top+i;
          this.balls[this.actionCount].backX = this.balls[this.actionCount].x;
          this.balls[this.actionCount].backY = this.balls[this.actionCount].y;
          this.ballActor.push(this.balls[this.actionCount]);
          this.actionCount++;
        }
      }
    }
    this.actorNumber = this.ballActor.length;
  }
  this.animateToText();
}
// 粒子运动到指定位置
Circle.prototype.animateToText = function(){
  for(var i=0;i<This.actorNumber;i++){
    dynamics.animate(This.ballActor[i], {
     x: this.ballActor[i].targetX,
     y: this.ballActor[i].targetY
    },{
      type: dynamics.easeIn,
      duration: 1024,
    });
  }
  setTimeout(function(){
    This.ballbackType();
  },3000);
}
// 粒子原路返回
Circle.prototype.ballBackPosition = function(){
  for(var i=0;i<This.actorNumber;i++){
    var ball = This.ballActor[i];
    dynamics.animate(ball, {
     x: ball.backX,
     y: ball.backY
    },{
      type: dynamics[this.backDynamics],
      duration: 991,
      complete:this.changeStatus(ball)
    });
  }
}
// 获取类型|动画效果
Circle.prototype.getAnimateType = function() {
  var selectType = document.getElementById("selectType");
  var selectDynamics = document.getElementById("selectDynamics");
  this.backType = selectType.options[selectType.options.selectedIndex].value;
  this.backDynamics = selectDynamics.options[selectDynamics.options.selectedIndex].value;
}
// 复位散开
Circle.prototype.ballbackType = function(){
  if(this.backType == "back"){
    this.ballBackPosition();
  }else{
    this.ballAutoPosition();
  }
  this.ballActor = [];
}
// 随机散开
Circle.prototype.ballAutoPosition = function(ball){
  for(var i=0;i<this.actorNumber;i++){
    this.changeStatus(this.ballActor[i])
  }
}
// 更改小球状态
Circle.prototype.changeStatus = function(ball){
  ball.status = 0;
  if(this.isPlay == true){
    this.isPlay = false;
  }
}
// 随机生成每个圆的相关参数
Circle.prototype.generalRandomParam = function(){
  for(var i=0;i<this.ballNumber;i++){
    var ball = {};
    ball.size = 1; // 随机生成圆半径
    // 随机生成圆心 x 坐标
    ball.x = ramdomNumber(0+ball.size, this.iCanvasW-ball.size);
    ball.y = ramdomNumber(0+ball.size, this.iCanvasH-ball.size);
    ball.speedX = ramdomNumber(-1, 1);
    ball.speedY = ramdomNumber(-1, 1);
    this.balls.push(ball);
    ball.status = 0;
    ball.targetX = 0;
    ball.targetY = 0;
    ball.backX = 0;
    ball.backY = 0;
  }
}
// 改变圆的位置
Circle.prototype.changeposition = function(){
  for(var i=0;i<this.ballNumber;i++){
    if( this.balls[i].status == 0){
      this.balls[i].x += this.balls[i].speedX;
      this.balls[i].y += this.balls[i].speedY;
    }
  }
}
// 画圆
Circle.prototype.renderBall = function(ball){
  this.ctx.fillStyle = "#fff";
  this.ctx.beginPath(); // 这个一定要加
  this.ctx.arc(ball.x, ball.y, ball.size, 0, 2 * Math.PI);
  this.ctx.closePath(); // 这个一定要加
  this.ctx.fill();
}
// 小球碰撞判断
Circle.prototype.collision = function(ball){
  for(var i=0;i<this.ballNumber;i++){
    if(ball.x>this.iCanvasW-ball.size || ball.x<ball.size){
      if(ball.x>this.iCanvasW-ball.size){
        ball.x = this.iCanvasW-ball.size;
      }else{
        ball.x = ball.size;
      }
      ball.speedX = - ball.speedX;
    }
    if(ball.y>this.iCanvasH-ball.size || ball.y<ball.size){
      if(ball.y>this.iCanvasH-ball.size){
        ball.y = this.iCanvasH-ball.size;
      }else{
        ball.y = ball.size;
      }
      ball.speedY = - ball.speedY;
    }
  }
}
// 开始动画
Circle.prototype.ballAnimate = function(){
  var This = this;
  var animateFrame = window.requestAnimationFrame || window.mozRequestAnimationFrame || window.webkitRequestAnimationFrame || window.msRequestAnimationFrame;
  (function move(){
    animte = animateFrame(move);
    This.ctx.clearRect(0, 0, This.iCanvasW, This.iCanvasH);
    This.changeposition();
    for(var i=0;i<This.ballNumber;i++){
      This.collision(This.balls[i]);
      This.renderBall(This.balls[i]);
    }
  })();
}
// 生成一个随机数
function ramdomNumber(min, max) {
  return Math.random() * (max - min) + min;
}

看了代码估计也只是心里炫了一下,也没有让你想把这个东西做出来的欲望,为此我知道必需得让你眼睛心服口服才行。在线 DEMO: 动感的粒子示例。

人无完人,代码也一样。看起来运行顺畅的代码也或多或少有一些瑕疵,日前这个效果还只支持中文。英文的话,我得再努力一把,不管怎么样,英文后面肯定是会加入来的,只是时间问题了。还有代码中用于标记是否可再次执行生成文字的 属性:this.isPlay ,还是一点瑕疵,this.isPlay 的状态更改没有准确的在粒子归位的那一瞬间更改,而是提前更改了状态。但这个状态不会影响本例子效果的完整实现。

这个例子中用到了 dynamics.js 库,主要是用到它里面的一些运动函数,让粒子动起来更感人一些,仅此而已。

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持申博开户。


本文地址:http://www.cvmachine.com/a/question/97497.html
Tags: 实现 canvas 详解
编辑:申博开户网
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