打ち上げ花火 - OpenProcessing

mySketch
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let vecLocation =[];
let vecVelocity = [];
let ballColor1 = [];
let ballColor2 = [];
let ballColor3 = [];
const NUM = 500;
let time = 0;
let lx;
let ly;
let vx;
let which;
let lay;
function setup() {
  createCanvas(windowWidth, windowHeight);
  frameRate(60);
  lx = random(50,width-50);
  ly = random(50,height-50);
  for(let i = 0; i<NUM; i++){
    which = random(2);
    lay = random(5);
    vecLocation[i] = createVector(lx, ly);
    if(lay<1){
      vx = random(-10, 10)
      if(which<1){
        vecVelocity[i] = createVector(vx, Math.sqrt(100-vx*vx));
      }else{
        vecVelocity[i] = createVector(vx, -Math.sqrt(100-vx*vx));
      }
    }else if(lay<2){
      vx = random(-Math.sqrt(80), Math.sqrt(80))
      if(which<1){
        vecVelocity[i] = createVector(vx, Math.sqrt(80-vx*vx));
      }else{
        vecVelocity[i] = createVector(vx, -Math.sqrt(80-vx*vx));
      }
    }
    else if(lay<3){
      vx = random(-Math.sqrt(60), Math.sqrt(60))
      if(which<1){
        vecVelocity[i] = createVector(vx, Math.sqrt(60-vx*vx));
      }else{
        vecVelocity[i] = createVector(vx, -Math.sqrt(60-vx*vx));
      }
    }
    else if(lay<4){
      vx = random(-Math.sqrt(40), Math.sqrt(40))
      if(which<1){
        vecVelocity[i] = createVector(vx, Math.sqrt(40-vx*vx));
      }else{
        vecVelocity[i] = createVector(vx, -Math.sqrt(40-vx*vx));
      }
    }
    else{
      vx = random(-Math.sqrt(20), Math.sqrt(20))
      if(which<1){
        vecVelocity[i] = createVector(vx, Math.sqrt(20-vx*vx));
      }else{
        vecVelocity[i] = createVector(vx, -Math.sqrt(20-vx*vx));
      }
    }
    
    ballColor1[i] = random(255);
    ballColor2[i] = random(255);
    ballColor3[i] = random(255);
  }
​
}
​
function draw() {
  background(0);
  
  if(time<240){
    fill(255, 250, 200, 255);
    ellipse(lx, ly, time, time);
    fill(255);
    noStroke();
    rect(lx, ly-time/2, 4, -20+time/12);
    fill(255, 0, 0);
    rect(lx, ly-time/2-20+time/12, 4, 5);
  }else{
    noStroke();
    for(let i = 0; i < NUM; i++){
      fill(ballColor1[i],ballColor2[i],ballColor3[i],120);
      ellipse(vecLocation[i].x, vecLocation[i].y, time-240, time-240);
      vecLocation[i].add(vecVelocity[i]);
    }
  }
  
  time += 1;
}