溫馨提示×
您好，登錄后才能下訂單哦！
點(diǎn)擊 登錄注冊(cè) 即表示同意《億速云用戶服務(wù)條款》
您好，登錄后才能下訂單哦！
小編給大家分享一下JavaScript中實(shí)現(xiàn)煙花綻放動(dòng)畫效果的方法，相信大部分人都還不怎么了解，因此分享這篇文章給大家參考一下，希望大家閱讀完這篇文章后大有收獲，下面讓我們一起去了解一下吧！
先編寫一個(gè)煙花綻放的動(dòng)畫效果。
放煙花時(shí)，一個(gè)煙花可分為兩個(gè)階段：（1）煙花上升到空中；（2）煙花炸開成碎片，炸開的碎片慢慢消散。
為此抽象出兩個(gè)對(duì)象類：Firework和Particle。其中，F(xiàn)irework用于表示一個(gè)煙花對(duì)象，Particle用于表示一個(gè)煙花炸開后的各碎片。
Firework對(duì)象類定義6個(gè)屬性：表示煙花上升軌跡中各點(diǎn)的坐標(biāo)（x,y）、煙花弧狀軌跡的偏轉(zhuǎn)角度angle、上升階段水平和垂直方向的位移改變量xSpeed和ySpeed、煙花的色彩色相hue。
坐標(biāo)屬性值y的初始值取畫布的高度，表示煙花從地面上升到空中，其余各屬性的初始值采用隨機(jī)數(shù)確定。具體定義如下：
function Firework()
{
this.x = canvas.width/4*(1+3*Math.random());
this.y = canvas.height - 15;
this.angle = Math.random() * Math.PI / 4 - Math.PI / 6;
this.xSpeed = Math.sin(this.angle) *(6+Math.random()*7);
this.ySpeed = -Math.cos(this.angle) *(6+Math.random()*7);
this.hue = Math.floor(Math.random() * 360);
}Firework對(duì)象類定義3個(gè)方法：繪制煙花上升軌跡的方法draw()、煙花上升時(shí)坐標(biāo)改變方法update()和煙花炸開方法explode()。繪制煙花軌跡時(shí)，在各點(diǎn)（x,y）處繪制一個(gè)寬度為5、高度為15的填充小矩形表示一個(gè)軌跡點(diǎn)。煙花上升時(shí)，垂直方向速度ySpeed初始值為負(fù)的，每次上升時(shí)，ySpeed加上一個(gè)正值，表示上升在減速，當(dāng)ySpeed的值大于0時(shí)，煙花上升到頂了（不能再上升），就炸開為70個(gè)碎片。具體方法的實(shí)現(xiàn)見后面的HTML文件內(nèi)容。
Particle對(duì)象類定義8個(gè)屬性：表示碎片散開軌跡中各點(diǎn)的坐標(biāo)（x,y）、碎片弧狀軌跡的偏轉(zhuǎn)角度angle、散開時(shí)水平和垂直方向的位移改變量xSpeed和ySpeed、碎片的色彩色相hue、表示碎片小圓的半徑size、碎片的亮度lightness。
function Particle(x,y,hue)
{
this.x = x;
this.y = y;
this.hue = hue;
this.lightness = 50;
this.size = 15 + Math.random() * 10;
this.angle = Math.random() * 2 * Math.PI;
this.xSpeed = Math.cos(this.angle) *(1+Math.random() * 6);
this.ySpeed = Math.sin(this.angle) *(1+Math.random() * 6);
}Particle對(duì)象類定義2個(gè)方法：繪制碎片散開軌跡的方法draw()、碎片散開時(shí)坐標(biāo)改變方法update()。碎片散開時(shí)逐漸變?。▽傩詓ize值減量），當(dāng)size值小于1時(shí)，從碎片數(shù)組中刪除該碎片，表示碎片已消亡。
定義兩個(gè)數(shù)組var fireworks=[];和var particles=[];分別存儲(chǔ)煙花對(duì)象和炸開的碎片對(duì)象。
模擬動(dòng)畫的函數(shù)loop中，每隔一段時(shí)間（用count計(jì)數(shù)來實(shí)現(xiàn)）向fireworks數(shù)組中添加一個(gè)煙花對(duì)象，煙花對(duì)象上升到頂炸開后，從fireworks數(shù)組中刪除該對(duì)象元素，然后向particles數(shù)組中添加70個(gè)碎片對(duì)象。
遍歷兩個(gè)數(shù)組的各對(duì)象，分別調(diào)用它們的draw()和update()方法。
編寫的完整HTML文件內(nèi)容如下。
<html>
<head>
<title>煙花綻放</title>
</head>
<body>
<canvas id="myCanvas" width="800" height="600" >
</canvas>
<script type="text/javascript">
var canvas=document.getElementById('myCanvas');
ctx= canvas.getContext('2d');
var fireworks=[];
var particles=[];
var counter = 0;
function Firework()
{
this.x = canvas.width/4*(1+3*Math.random());
this.y = canvas.height - 15;
this.angle = Math.random() * Math.PI / 4 - Math.PI / 6;
this.xSpeed = Math.sin(this.angle) *(6+Math.random()*7);
this.ySpeed = -Math.cos(this.angle) *(6+Math.random()*7);
this.hue = Math.floor(Math.random() * 360);
}
Firework.prototype.draw= function()
{
ctx.save();
ctx.translate(this.x, this.y);
ctx.rotate(Math.atan2(this.ySpeed, this.xSpeed) + Math.PI / 2);
ctx.fillStyle =`hsl(${this.hue}, 100%, 50%)`;
ctx.fillRect(0, 0, 5, 15);
ctx.restore();
}
Firework.prototype.update= function()
{
this.x = this.x + this.xSpeed;
this.y = this.y + this.ySpeed;
this.ySpeed += 0.1;
}
Firework.prototype.explode= function()
{
for (var i = 0; i < 70; i++)
{
particles.push(new Particle(this.x, this.y, this.hue));
}
}
function Particle(x,y,hue)
{
this.x = x;
this.y = y;
this.hue = hue;
this.lightness = 50;
this.size = 15 + Math.random() * 10;
this.angle = Math.random() * 2 * Math.PI;
this.xSpeed = Math.cos(this.angle) *(1+Math.random() * 6);
this.ySpeed = Math.sin(this.angle) *(1+Math.random() * 6);
}
Particle.prototype.draw= function()
{
ctx.fillStyle = `hsl(${this.hue}, 100%, ${this.lightness}%)`;
ctx.beginPath();
ctx.arc(this.x, this.y, this.size, 0, 2 * Math.PI);
ctx.closePath();
ctx.fill();
}
Particle.prototype.update= function(index)
{
this.ySpeed += 0.05;
this.size = this.size*0.95;
this.x = this.x + this.xSpeed;
this.y = this.y + this.ySpeed;
if (this.size<1)
{
particles.splice(index,1);
}
}
function loop()
{
ctx.fillStyle = "rgba(0, 0, 0, 0.1)";
ctx.fillRect(0,0,canvas.width,canvas.height);
counter++;
if (counter==15)
{
fireworks.push(new Firework());
counter=0;
}
var i=fireworks.length;
while (i--)
{
fireworks[i].draw();
fireworks[i].update();
if (fireworks[i].ySpeed > 0)
{
fireworks[i].explode();
fireworks.splice(i, 1);
}
}
var i=particles.length;
while (i--)
{
particles[i].draw();
particles[i].update(i);
}
requestAnimationFrame(loop);
}
loop();
</script>
</body>
</html>在瀏覽器中打開包含這段HTML代碼的html文件，可以看到在瀏覽器窗口中呈現(xiàn)出如圖所示的煙花綻放動(dòng)畫效果。
實(shí)現(xiàn)了煙花綻放的效果，我們還可以繼續(xù)讓一定區(qū)域內(nèi)的綻放的煙花碎片拼成“Happy New Year”粒子文本。
編寫如下的HTML代碼。
<html>
<head>
<title>迎新年煙花綻放</title>
<style>
body { margin: 0; background: black; }
canvas { position: absolute; }
</style>
</head>
<body>
<canvas id="myCanvas1"></canvas>
<canvas id="myCanvas2"></canvas>
<canvas id="myCanvas3"></canvas>
<script type="text/javascript">
function Particle(x, y, hue)
{
this.x = x;
this.y = y;
this.hue = hue;
this.lightness = 50;
this.size = 15 + Math.random() * 10;
this.angle = Math.random() * 2 * Math.PI;
this.xSpeed = Math.cos(this.angle) * (1 + Math.random() * 6);
this.ySpeed = Math.sin(this.angle) * (1 + Math.random() * 6);
this.target = getTarget();
this.timer = 0;
}
Particle.prototype.draw= function()
{
ctx2.fillStyle =`hsl(${this.hue}, 100%, ${this.lightness}%)`;
ctx2.beginPath();
ctx2.arc(this.x, this.y, this.size, 0, 2 * Math.PI);
ctx2.closePath();
ctx2.fill();
}
Particle.prototype.update= function(idx)
{
if (this.target)
{
var dx = this.target.x - this.x;
var dy = this.target.y - this.y;
var dist = Math.sqrt(dx * dx + dy * dy);
var a = Math.atan2(dy, dx);
var tx = Math.cos(a) * 5;
var ty = Math.sin(a) * 5;
this.size = lerp(this.size, 1.5, 0.05);
if (dist < 5)
{
this.lightness = lerp(this.lightness, 100, 0.01);
this.xSpeed = this.ySpeed = 0;
this.x = lerp(this.x, this.target.x + fidelity / 2, 0.05);
this.y = lerp(this.y, this.target.y + fidelity / 2, 0.05);
this.timer += 1;
}
else if (dist < 10)
{
this.lightness = lerp(this.lightness, 100, 0.01);
this.xSpeed = lerp(this.xSpeed, tx, 0.1);
this.ySpeed = lerp(this.ySpeed, ty, 0.1);
this.timer += 1;
}
else
{
this.xSpeed = lerp(this.xSpeed, tx, 0.02);
this.ySpeed = lerp(this.ySpeed, ty, 0.02);
}
}
else
{
this.ySpeed += 0.05;
this.size = this.size*0.95;
if (this.size<1)
{
particles.splice(idx,1);
}
}
this.x = this.x + this.xSpeed;
this.y = this.y + this.ySpeed;
}
function Firework()
{
this.x = canvas2.width*(1+ 3*Math.random())/4;
this.y = canvas2.height - 15;
this.angle = Math.random() * Math.PI / 4 - Math.PI / 6;
this.xSpeed = Math.sin(this.angle) * (6 + Math.random() * 7);
this.ySpeed = -Math.cos(this.angle) * (6 + Math.random() * 7);
this.hue = Math.floor(Math.random() * 360);
}
Firework.prototype.draw= function()
{
ctx2.save();
ctx2.translate(this.x, this.y);
ctx2.rotate(Math.atan2(this.ySpeed, this.xSpeed) + Math.PI / 2);
ctx2.fillStyle = `hsl(${this.hue}, 100%, 50%)`;
ctx2.fillRect(0, 0, 5, 15);
ctx2.restore();
}
Firework.prototype.update= function()
{
this.x = this.x + this.xSpeed;
this.y = this.y + this.ySpeed;
this.ySpeed += 0.1;
}
Firework.prototype.explode= function()
{
for (var i = 0; i < 70; i++)
{
particles.push(new Particle(this.x, this.y, this.hue));
}
}
function lerp(a, b, t)
{
return Math.abs(b - a)> 0.1 ? a + t * (b - a) : b;
}
function getTarget()
{
if (targets.length > 0)
{
var idx = Math.floor(Math.random() * targets.length);
var { x, y } = targets[idx];
targets.splice(idx, 1);
x += canvas2.width / 2 - textWidth / 2;
y += canvas2.height / 2 - fontSize / 2;
return { x, y };
}
}
var canvas1=document.getElementById('myCanvas1');
ctx1= canvas1.getContext('2d');
var canvas2=document.getElementById('myCanvas2');
ctx2= canvas2.getContext('2d');
var canvas3=document.getElementById('myCanvas3');
ctx3= canvas3.getContext('2d');
var fontSize = 200;
var fireworks = [];
var particles = [];
var targets = [];
var fidelity = 3;
var counter = 0;
canvas2.width = canvas3.width = window.innerWidth;
canvas2.height = canvas3.height = window.innerHeight;
ctx1.fillStyle = '#000';
var text = 'Happy New Year';
var textWidth = 999999;
while (textWidth > window.innerWidth)
{
ctx1.font = `900 ${fontSize--}px Arial`;
textWidth = ctx1.measureText(text).width;
}
canvas1.width = textWidth;
canvas1.height = fontSize * 1.5;
ctx1.font = `900 ${fontSize}px Arial`;
ctx1.fillText(text, 0, fontSize);
var imgData = ctx1.getImageData(0, 0, canvas1.width, canvas1.height);
for (var i = 0, max = imgData.data.length; i < max; i += 4)
{
var alpha = imgData.data[i + 3];
var x = Math.floor(i / 4) % imgData.width;
var y = Math.floor(i / 4 / imgData.width);
if (alpha && x % fidelity === 0 && y % fidelity === 0)
{
targets.push({ x, y });
}
}
ctx3.fillStyle = '#FFF';
ctx3.shadowColor = '#FFF';
ctx3.shadowBlur = 25;
function loop()
{
ctx2.fillStyle = "rgba(0, 0, 0, .1)";
ctx2.fillRect(0, 0, canvas2.width, canvas2.height);
counter += 1;
if (counter==15)
{
fireworks.push(new Firework());
counter=0;
}
var i=fireworks.length;
while (i--)
{
fireworks[i].draw();
fireworks[i].update();
if (fireworks[i].ySpeed > 0)
{
fireworks[i].explode();
fireworks.splice(i, 1);
}
}
var i=particles.length;
while (i--)
{
particles[i].draw();
particles[i].update(i);
if (particles[i].timer >= 100 || particles[i].lightness >= 99)
{
ctx3.fillRect(particles[i].target.x, particles[i].target.y, fidelity + 1, fidelity + 1);
particles.splice(i, 1);
}
}
requestAnimationFrame(loop);
}
loop();
</script>
</body>
</html>在瀏覽器中打開包含這段HTML代碼的html文件，可以看到在瀏覽器窗口中呈現(xiàn)出如圖所示的煙花綻放迎新年動(dòng)畫效果。圖2中為了控制圖片的大小，刪除了大量的中間幀，因此和實(shí)際運(yùn)行的效果有所不同。
以上是JavaScript中實(shí)現(xiàn)煙花綻放動(dòng)畫效果的方法的所有內(nèi)容，感謝各位的閱讀！相信大家都有了一定的了解，希望分享的內(nèi)容對(duì)大家有所幫助，如果還想學(xué)習(xí)更多知識(shí)，歡迎關(guān)注億速云行業(yè)資訊頻道！
免責(zé)聲明：本站發(fā)布的內(nèi)容（圖片、視頻和文字）以原創(chuàng)、轉(zhuǎn)載和分享為主，文章觀點(diǎn)不代表本網(wǎng)站立場(chǎng)，如果涉及侵權(quán)請(qǐng)聯(lián)系站長(zhǎng)郵箱：is@yisu.com進(jìn)行舉報(bào)，并提供相關(guān)證據(jù)，一經(jīng)查實(shí)，將立刻刪除涉嫌侵權(quán)內(nèi)容。
億速云公眾號(hào)
手機(jī)網(wǎng)站二維碼