本文主要是介绍Canvas模拟火焰燃烧效果示例，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
canvas实例应用100+专栏提供canvas的基础知识，高级动画，相关应用扩展等信息。
canvas作为html的一部分，是图像图标地图可视化的一个重要的基础，学好了canvas，在其他的一些应用上将会起到非常重要的帮助。
文章目录
- 示例效果
- 源代码
- canvas基本属性
- canvas基础方法
canvas能做好很多事情，能显示各种动画。这里是模拟火焰燃烧效果的示例。
示例效果
源代码
<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>Canvas模拟火焰演示</title><style>
@import url(https://fonts.googleapis.com/css?family=Amatic+SC);
html, body {margin:0;padding:0;height: 100%;
}
</style></head>
<body>
<canvas id="zjcopy"></canvas><script>
var Fire = function(){this.canvas = document.getElementById('zjcopy');this.ctx = this.canvas.getContext('2d');this.canvas.height = window.innerHeight;this.canvas.width = window.innerWidth;this.aFires = [];this.aSpark = [];this.aSpark2 = [];this.mouse = {x : this.canvas.width * .5,y : this.canvas.height * .75,}this.init();}
Fire.prototype.init = function()
{this.canvas.addEventListener('mousemove', this.updateMouse.bind( this ), false);}
Fire.prototype.run = function(){this.update();this.draw();if( this.bRuning )requestAnimationFrame( this.run.bind( this ) );}
Fire.prototype.start = function(){this.bRuning = true;this.run();}
Fire.prototype.stop = function(){this.bRuning = false;}
Fire.prototype.update = function(){this.aFires.push( new Flame( this.mouse ) );this.aSpark.push( new Spark( this.mouse ) );this.aSpark2.push( new Spark( this.mouse ) );for (var i = this.aFires.length - 1; i >= 0; i--) {if( this.aFires[i].alive )this.aFires[i].update();elsethis.aFires.splice( i, 1 );}for (var i = this.aSpark.length - 1; i >= 0; i--) {if( this.aSpark[i].alive )this.aSpark[i].update();elsethis.aSpark.splice( i, 1 );}for (var i = this.aSpark2.length - 1; i >= 0; i--) {if( this.aSpark2[i].alive )this.aSpark2[i].update();elsethis.aSpark2.splice( i, 1 );}}Fire.prototype.draw = function(){this.ctx.globalCompositeOperation = "source-over";this.ctx.fillStyle = "rgba( 15, 5, 2, 1 )";this.ctx.fillRect( 0, 0, window.innerWidth, window.innerHeight );this.grd = this.ctx.createRadialGradient( this.mouse.x, this.mouse.y - 200,200,this.mouse.x, this.mouse.y - 100,0 );this.grd.addColorStop(0,"rgb( 15, 5, 2 )");this.grd.addColorStop(1,"rgb( 30, 10, 2 )");this.ctx.beginPath();this.ctx.arc( this.mouse.x, this.mouse.y - 100, 200, 0, 2*Math.PI );this.ctx.fillStyle= this.grd;this.ctx.fill();this.ctx.font = "15em Amatic SC";this.ctx.textAlign = "center";this.ctx.strokeStyle = "rgb(50, 20, 0)";this.ctx.fillStyle = "rgb(120, 10, 0)";this.ctx.lineWidth = 2;this.ctx.strokeText("Fire",this.canvas.width/2, this.canvas.height * .72 );this.ctx.fillText("Fire",this.canvas.width/2, this.canvas.height * .72 ); this.ctx.globalCompositeOperation = "overlay";//or lighter or soft-lightfor (var i = this.aFires.length - 1; i >= 0; i--) {this.aFires[i].draw( this.ctx );}this.ctx.globalCompositeOperation = "soft-light";//"soft-light";//"color-dodge";for (var i = this.aSpark.length - 1; i >= 0; i--) {if( ( i % 2 ) === 0 )this.aSpark[i].draw( this.ctx );}this.ctx.globalCompositeOperation = "color-dodge";//"soft-light";//"color-dodge";for (var i = this.aSpark2.length - 1; i >= 0; i--) {this.aSpark2[i].draw( this.ctx );}}Fire.prototype.updateMouse = function( e ){this.mouse.x = e.clientX;this.mouse.y = e.clientY;//this.aFires.push( new Flame( this.mouse ) );}var Flame = function( mouse ){this.cx = mouse.x;this.cy = mouse.y;this.x = rand( this.cx - 25, this.cx + 25);this.y = rand( this.cy - 5, this.cy + 5);this.vy = rand( 1, 3 );this.vx = rand( -1, 1 );this.r = rand( 20, 30 );this.life = rand( 3, 6 );this.alive = true;this.c = {h : Math.floor( rand( 2, 40) ),s : 100,l : rand( 80, 100 ),a : 0,ta : rand( 0.8, 0.9 )}}
Flame.prototype.update = function()
{this.y -= this.vy;this.vy += 0.05;this.x += this.vx;if( this.x < this.cx )this.vx += 0.1;elsethis.vx -= 0.1;if( this.r > 0 )this.r -= 0.1;if( this.r <= 0 )this.r = 0;this.life -= 0.15;if( this.life <= 0 ){this.c.a -= 0.05;if( this.c.a <= 0 )this.alive = false;}else if( this.life > 0 && this.c.a < this.c.ta ){this.c.a += .08;}}
Flame.prototype.draw = function( ctx ){ctx.beginPath();ctx.arc( this.x, this.y, this.r * 3, 0, 2*Math.PI );ctx.fillStyle = "hsla( " + this.c.h + ", " + this.c.s + "%, " + this.c.l + "%, " + (this.c.a/20) + ")";ctx.fill();ctx.beginPath();ctx.arc( this.x, this.y, this.r, 0, 2*Math.PI );ctx.fillStyle = "hsla( " + this.c.h + ", " + this.c.s + "%, " + this.c.l + "%, " + this.c.a + ")";ctx.fill();}var Spark = function( mouse ){this.cx = mouse.x;this.cy = mouse.y;this.x = rand( this.cx -40, this.cx + 40);this.y = rand( this.cy, this.cy + 5);this.lx = this.x;this.ly = this.y;this.vy = rand( 1, 3 );this.vx = rand( -4, 4 );this.r = rand( 0, 1 );this.life = rand( 4, 5 );this.alive = true;this.c = {h : Math.floor( rand( 2, 40) ),s : 100,l : rand( 40, 100 ),a : rand( 0.8, 0.9 )}}
Spark.prototype.update = function()
{this.lx = this.x;this.ly = this.y;this.y -= this.vy;this.x += this.vx;if( this.x < this.cx )this.vx += 0.2;elsethis.vx -= 0.2;this.vy += 0.08;this.life -= 0.1;if( this.life <= 0 ){this.c.a -= 0.05;if( this.c.a <= 0 )this.alive = false;}}
Spark.prototype.draw = function( ctx ){ctx.beginPath();ctx.moveTo( this.lx , this.ly);ctx.lineTo( this.x, this.y);ctx.strokeStyle = "hsla( " + this.c.h + ", " + this.c.s + "%, " + this.c.l + "%, " + (this.c.a / 2) + ")";ctx.lineWidth = this.r * 2;ctx.lineCap = 'round';ctx.stroke();ctx.closePath();ctx.beginPath();ctx.moveTo( this.lx , this.ly);ctx.lineTo( this.x, this.y);ctx.strokeStyle = "hsla( " + this.c.h + ", " + this.c.s + "%, " + this.c.l + "%, " + this.c.a + ")";ctx.lineWidth = this.r;ctx.stroke();ctx.closePath();}rand = function( min, max ){ return Math.random() * ( max - min) + min; };
onresize = function () { oCanvas.canvas.width = window.innerWidth; oCanvas.canvas.height = window.innerHeight; };var oCanvas;
init = function()
{oCanvas = new Fire();oCanvas.start();}window.onload = init;
</script></body>
</html>canvas基本属性
| 属性 | 属性 | 属性 |
|---|---|---|
| canvas | fillStyle | filter |
| font | globalAlpha | globalCompositeOperation |
| height | lineCap | lineDashOffset |
| lineJoin | lineWidth | miterLimit |
| shadowBlur | shadowColor | shadowOffsetX |
| shadowOffsetY | strokeStyle | textAlign |
| textBaseline | width |
canvas基础方法
| 方法 | 方法 | 方法 |
|---|---|---|
| arc() | arcTo() | addColorStop() |
| beginPath() | bezierCurveTo() | clearRect() |
| clip() | close() | closePath() |
| createImageData() | createLinearGradient() | createPattern() |
| createRadialGradient() | drawFocusIfNeeded() | drawImage() |
| ellipse() | fill() | fillRect() |
| fillText() | getImageData() | getLineDash() |
| isPointInPath() | isPointInStroke() | lineTo() |
| measureText() | moveTo() | putImageData() |
| quadraticCurveTo() | rect() | restore() |
| rotate() | save() | scale() |
| setLineDash() | setTransform() | stroke() |
| strokeRect() | strokeText() | transform() |
| translate() |
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