canvas火焰效果程式碼例項

admin發表於2017-02-28
原文網址 : https://www.softwhy.com/article-2065-1.html
Canvas
分享一段程式碼例項，它實現了火焰燃燒的動態效果。

程式碼例項如下:

[HTML] 純文字檢視 複製程式碼執行程式碼
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<meta name="author" content="http://www.softwhy.com/" />
<title>螞蟻部落</title>
<style type="text/css">
body {
  background: rgb(36, 36, 36);
  text-align: center;
}
#fire {
  width: 100%;
  height: 100%;
}
</style>
<script src="http://libs.baidu.com/jquery/1.9.0/jquery.js"></script>
<script type="text/javascript">
$(document).ready(function() {
  var space = document.getElementById("fire");
  var ctx = space.getContext("2d");
  var particles = [];
  var particle_count = 150;
  for (var i = 0; i < particle_count; i++) {
    particles.push(new particle());
  }
  var time = 0;
  var canvasWidth = 320;
  var canvasHeight = 480;
  $(".wrapper").css({
    width: canvasWidth,
    height: canvasHeight
  });
  $("#fire").css({
    width: canvasWidth,
    height: canvasHeight
  });
  window.requestAnimFrame = (function() {
    return window.requestAnimationFrame ||
      window.webkitRequestAnimationFrame ||
      window.mozRequestAnimationFrame ||
      function(callback) {
        window.setTimeout(callback, 6000 / 60);
      };
  })();
 
  function particle() {
    this.speed = {
      x: -1 + Math.random() * 2,
      y: -5 + Math.random() * 5
    };
    canvasWidth = (document.getElementById("fire").width);
    canvasHeight = (document.getElementById("fire").height);
    this.location = {
      x: canvasWidth / 2,
      y: (canvasHeight / 2) + 35
    };
    this.radius = 0.5 + Math.random() * 1;
    this.life = 10 + Math.random() * 10;
    this.death = this.life;
    this.r = 255;
    this.b = 0;
    this.g = Math.round(Math.random() * 52);
  }
 
  function ParticleAnimation() {
    ctx.globalCompositeOperation = "source-over";
    ctx.fillStyle = "rgb(36,36,36)";
    ctx.fillRect(0, 0, canvasWidth, canvasHeight);
    ctx.globalCompositeOperation = "lighter";
    for (var i = 0; i < particles.length; i++) {
      var p = particles[i];
      ctx.beginPath();
      p.opacity = Math.round(p.death / p.life * 100) / 100
      var gradient = ctx.createRadialGradient(p.location.x, p.location.y, 0, p.location.x, p.location.y, p.radius);
      gradient.addColorStop(0, "rgba(" + p.r + ", " + p.g + ", " + p.b + ", " + p.opacity + ")");
      gradient.addColorStop(0.5, "rgba(" + p.r + ", " + p.g + ", " + p.b + ", " + p.opacity + ")");
      gradient.addColorStop(1, "rgba(" + p.r + ", " + p.g + ", " + p.b + ", 0)");
      ctx.fillStyle = gradient;
      ctx.arc(p.location.x, p.location.y, p.radius, Math.PI * 2, false);
      ctx.fill();
      p.death--;
      p.radius++;
      p.location.x += (p.speed.x);
      p.location.y += (p.speed.y);
      if (p.death < 0 || p.radius < 0) {
        particles[i] = new particle();
      }
    }
    requestAnimFrame(ParticleAnimation);
  }
  ParticleAnimation();
});
</script>
</head>
<body>
<canvas id="fire"></canvas>
</body>
</html>

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