proximity study

let particles = []; // main array of 3000 particles

let proximityArray = []; // array to store nearby particles

​

function setup() {

  createCanvas(windowWidth, windowHeight);

  for (let i=0; i<3000; i++) particles.push(createVector(random(width), random(height)));

  noStroke();

}

​

function draw() {

  background(0);

  fill(127);

  // draw all particles

  for (let p of particles) ellipse(p.x, p.y, 5, 5);

​

  fill(255,0,0);

  // draw particles that are near the mouse

  for (let p of proximityArray) ellipse(p.x, p.y, 5, 5);

  noLoop(); // since the particles are not moving

}

​

// Only update proximityArray when mouse moves

function mouseMoved() {

  proximityArray = particles.filter(p => dist(p.x, p.y, mouseX, mouseY) < 100);

  proximityArray.sort((a, b) => dist(a.x, a.y, mouseX, mouseY) - dist(b.x, b.y, mouseX, mouseY));

  loop(); //re-render the scene

}