html5 canvas流星陨石掉落地面爆炸动画特效

代码片段：

this.update = function(i) {
this.rotation += this.velocity.rotate * this.timescale;
this.position.x +=
Math.cos(this.velocity.phi) * this.velocity.length * this.timescale;
this.position.y +=
Math.sin(this.velocity.phi) * this.velocity.length * this.timescale;
this.position.x +=
Math.cos(this.gravity.phi) * this.gravity.length * this.timescale;
this.position.y +=
Math.sin(this.gravity.phi) * this.gravity.length * this.timescale;
this.velocity.phi += this.accelerate.phi.change * this.timescale;
(this.velocity.phi > this.accelerate.phi.max ||
this.velocity.phi < this.accelerate.phi.min) &&
(this.accelerate.phi.change = -this.accelerate.phi.change);
this.velocity.length *= this.accelerate.friction;
if (this.position.y > this.ground) {
var ctx = this.vfx;
var position = this.position;
var range = this.edge;
var main = this.main;
[...new Array(this.edge)].map(
() =>
main.makeRock({
position: { x: position.x, y: position.y },
base: range
}) ||
LightFlare(
ctx,
position.x + Math.random() * 10 * range - 5 * range,
position.y + Math.random() * 6 * range - 3 * range,
range * Math.random() * 30 + 30
)
);
this.main.meteors.splice(i, 1);
this.main.makeMeteor();
}
};