const gridWidth = 40;
const gridHeight = 40;
const screenWidth = 700;
const screenHeight = 700;
var distX;
var distY;
var reactorPosition;
var vectLineList = [];

  
function setup() {
  reactorPosition = createVector(0, 0);
  createCanvas(700, 700);
  background(255);
  stroke(0);
  
  let distX = width/gridWidth+1;
  let distY = height/gridHeight+1;
  
  for (var i = 0; i<gridWidth; i++ ) {
    for (var j = 0; j<gridHeight; j++ ) {
      vectLineList.push(new VectorLine(i*distX, j*distY));
    }
  }
}
  
function draw() {
  background(255);
  for (var i = 0; i<vectLineList.length; i++ ) {
    vectLineList[i].show(reactorPosition);
  }
}
  
  
function mouseMoved() {
  reactorPosition.x = mouseX;
  reactorPosition.y = mouseY;
}
  
  
class VectorLine {

  constructor(x,y){
    this._vector = createVector(0, 5);
    this._pos = createVector(x, y);
    this._vector.add(this._pos);
    this.reactorScaler = 0.07;
  }

   show(reactor) {
    this._reactor  = reactor.copy();
    this.reactorDistance = dist(this._reactor.x, this._reactor.y, this._pos.x, this._pos.y);
    this.scaler = this.reactorDistance * this.reactorScaler;
    this._reactor.sub(this._pos); // subtract VectorLines position from the reactors position, this effectively gives a reactor coordinate relative to our VectorLine coordinate
    this._vector = this._reactor.copy();
    this._vector.normalize();
    this._vector.rotate(PI/4);
    this._vector.mult(this.scaler);
    this._vector.add(this._pos);
    //
    line(this._pos.x, this._pos.y, this._vector.x, this._vector.y);
    ellipse(this._vector.x,this._vector.y, 5, 5);
  }
}