Magical trail 2 - OpenProcessing

main.js
particle.js
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/*
Magical trail shader 2
​
Inspired by takawo's sketch:
  https://www.openprocessing.org/sketch/853212
​
Author:
  Jason Labbe
​
Site:
  jasonlabbe3d.com
 
Controls:
  - Move the mouse to create particles.
  - Hold the middle mouse button to fade away particles.
*/
​
const MAX_TRAIL_COUNT = 30;
​
var colorScheme = ["#0A1B28", "#071F43", "#357D7E", "#35EEEE", "#919DF0"];
var trail = [];
var particles = [];
​
function setup() {
  let canvas = createCanvas(windowWidth, windowHeight);
  canvas.canvas.oncontextmenu = () => false;  // Removes right-click menu.
  noCursor();
}
​
function draw() {
  blendMode(BLEND);
  background(0);
  blendMode(SCREEN);
  
  // Trim end of trail.
  trail.push([mouseX, mouseY]);
  
  let removeCount = 1;
  if (mouseIsPressed && mouseButton == CENTER) {
    removeCount++;
  }
  
  for (let i = 0; i < removeCount; i++) {
    if (trail.length == 0) {
      break;
    }
    
    if (mouseIsPressed || trail.length > MAX_TRAIL_COUNT) {
      trail.splice(0, 1);
    }
  }
  
  // Spawn particles.
  if (trail.length > 1) {
    let mouse = new p5.Vector(mouseX, mouseY);
    mouse.sub(pmouseX, pmouseY);
    if (mouse.mag() > 5) {
      mouse.normalize();
      for (let i = 0; i < 3; i++) {
        particles.push(new Particle(pmouseX, pmouseY, mouse.x, mouse.y));
      }
    }
  }
  
  // Move and kill particles.
  for (let i = particles.length - 1; i > -1; i--) {
    particles[i].move();
    if (particles[i].vel.mag() < 0.1) {
      particles.splice(i, 1);
    }
  }
  
  // Draw trail.
  drawingContext.shadowColor = color(0, 125, 255);
​
  for (let i = 0; i < trail.length; i++) {
    let mass = i * 1.5;
    drawingContext.shadowBlur = mass;
​
    stroke(0);
    strokeWeight(mass);
    point(trail[i][0], trail[i][1]);
  }
  
  // Draw particles.
  for (let i = 0; i < particles.length; i++) {
    let p = particles[i];
    let mass = p.mass * p.vel.mag() * 0.6;
​
    drawingContext.shadowColor = color(colorScheme[p.colorIndex]);
    drawingContext.shadowBlur = mass;
​
    stroke(0);
    strokeWeight(mass);
    point(p.pos.x, p.pos.y);
​
    stroke(255);
    strokeWeight(mass * 0.05);
    point(p.pos.x, p.pos.y);
  }
}