用p5.js制作烟花特效的示例代码

function setup() { //processing初始化设置
 createCanvas(window.innerWidth, window.innerHeight);
 frameRate(50);
 imageMode(CENTER);
}

function draw() { //循环执行，达成画面渲染效果
 background(0, 0, 40);
 for (var i = 0; i < fireworks.length; i++) {
  fireworks[i].display();
  fireworks[i].update();
  if (fireworks[i].needRemove()) {
   fireworks.splice(i, 1);
  }
 }
}

function Fireworks(radius) {
 var num = 512; //一发烟花里，有多少个点 (比较吃机器)
 var centerPosition = new p5.Vector(random(width / 8, width * 7 / 8), random(height / 2, height * 4 / 5), random(-100, 100)); //烟花的中心位置
 var velocity = new p5.Vector(0, -22, 0);
 var accel = new p5.Vector(0, 0.4, 0);
 var img;
 var firePosition = [];
 var cosTheta;
 var sinTheta;
 var phi;
 var colorChange = random(0, 5);

 for (var i = 0; i < num; i++) {
  cosTheta = random(0, 1) * 2 - 1;
  sinTheta = sqrt(1 - cosTheta * cosTheta);
  phi = random(0, 1) * 2 * PI;
  firePosition[i] = new p5.Vector(radius * sinTheta * cos(phi), radius * sinTheta * sin(phi), radius * cosTheta); //1发烟花里各个点的位置计算
  firePosition[i] = p5.Vector.mult(firePosition[i], 1.12);
 }

 //调整烟花随机颜色，使其更亮丽
 if(colorChange>=3.8){
  img=createLight(0.9,random(0.2,0.5),random(0.2,0.5));
 }else if(colorChange>3.2){
  img=createLight(random(0.2,0.5),0.9,random(0.2,0.5));
 }else if(colorChange>2){
  img=createLight(random(0.2,0.5),random(0.2,0.5),0.9);
 } else {
  img=createLight(random(0.5,0.8),random(0.5,0.8),random(0.5,0.8));
 }


 this.display = function () {
  for (var i = 0; i < num; i++) {
   push();
   translate(centerPosition.x, centerPosition.y, centerPosition.z);
   translate(firePosition[i].x, firePosition[i].y, firePosition[i].z);
   blendMode(ADD); //各个小点（发光源遮罩效果）
   image(img, 0, 0);
   pop();

   firePosition[i] = p5.Vector.mult(firePosition[i], 1.015); //更新小点（发光源）扩散位置
  } 
 }

 this.update = function () { //模拟重力加速度
  radius = dist(0, 0, 0, firePosition[0].x, firePosition[0].y, firePosition[0].z);
  centerPosition.add(velocity);
  velocity.add(accel);
 }

 this.needRemove = function () {
  if (centerPosition.y - radius > height) {
   return true;
  } else {
   return false;
  }
 }
}

function createLight(rPower, gPower, bPower) {
 var side = 64;
 var center = side / 2.0;
 var img = createImage(side, side);
 img.loadPixels();
 for (var y = 0; y < side; y++) {
  for (var x = 0; x < side; x++) {
   var distance = (sq(center - x) + sq(center - y)) / 10.0;
   var r = int((255 * rPower) / distance);
   var g = int((255 * gPower) / distance);
   var b = int((255 * bPower) / distance);
   // img.pixels[x + y * side] = color(r, g, b);
   img.set(y, x, color(r, g, b));
  }
 }

 img.updatePixels();
 return img;
}

function keyPressed() { //每事件添加一发烟花
 fireworks.push(new Fireworks(80)); //80为烟花初始半径
}

function touchStarted() { //每事件添加一发烟花
 fireworks.push(new Fireworks(80));
 return false;
}