谁给改改版
配置项如下
var $ = {};
$.Particle = function (opt) {
this.radius = 7;
this.x = opt.x;
this.y = opt.y;
this.angle = opt.angle;
this.speed = opt.speed;
this.accel = opt.accel;
this.decay = 0.01;
this.life = 1;
};
$.Particle.prototype.step = function (i) {
this.speed += this.accel;
this.x += Math.cos(this.angle) * this.speed;
this.y += Math.sin(this.angle) * this.speed;
this.angle += $.PI / 64;
this.accel *= 1.01;
this.life -= this.decay;
if (this.life <= 0) {
$.particles.splice(i, 1);
}
};
$.Particle.prototype.draw = function (i) {
$.ctx.fillStyle = $.ctx.strokeStyle = 'hsla(' + ($.tick + this.life * 120) + ', 100%, 60%, ' + this.life + ')';
$.ctx.beginPath();
if ($.particles[i - 1]) {
$.ctx.moveTo(this.x, this.y);
$.ctx.lineTo($.particles[i - 1].x, $.particles[i - 1].y);
}
$.ctx.stroke();
$.ctx.beginPath();
$.ctx.arc(this.x, this.y, Math.max(0.001, this.life * this.radius), 0, $.TWO_PI);
$.ctx.fill();
var size = Math.random() * 1.25;
$.ctx.fillRect(
~~(this.x + (Math.random() - 0.5) * 35 * this.life),
~~(this.y + (Math.random() - 0.5) * 35 * this.life),
size,
size
);
};
$.step = function () {
$.particles.push(
new $.Particle({
x: $.width / 2 + (Math.cos($.tick / 20) * $.min) / 2,
y: $.height / 2 + (Math.sin($.tick / 20) * $.min) / 2,
angle: $.globalRotation + $.globalAngle,
speed: 0,
accel: 0.01,
})
);
$.particles.forEach(function (elem, index) {
elem.step(index);
});
$.globalRotation += $.PI / 6;
$.globalAngle += $.PI / 6;
};
$.draw = function () {
$.ctx.clearRect(0, 0, $.width, $.height);
$.particles.forEach(function (elem, index) {
elem.draw(index);
});
};
$.init = function () {
document.body.style.backgroundColor = '#000E1a';
$.canvas = document.createElement('canvas');
$.ctx = $.canvas.getContext('2d');
$.width = 500;
$.height = 500;
$.canvas.width = $.width * window.devicePixelRatio;
$.canvas.height = $.height * window.devicePixelRatio;
$.canvas.style.width = $.width + 'px';
$.canvas.style.height = $.height + 'px';
$.ctx.scale(window.devicePixelRatio, window.devicePixelRatio);
$.min = $.width * 0.5;
$.particles = [];
$.globalAngle = 0;
$.globalRotation = 0;
$.tick = 0;
$.PI = Math.PI;
$.TWO_PI = $.PI * 2;
$.ctx.globalCompositeOperation = 'lighter';
document.body.appendChild($.canvas);
$.loop();
};
$.loop = function () {
requestAnimationFrame($.loop);
$.step();
$.draw();
$.tick++;
};
$.init();