constructor(_m, _b, _color) {

    this.set(_m, _b);

    this.color = _color;

  }

​

  set(_m, _b) {

    this.m = _m;

    this.b = _b;

    this.pVect = createVector(this.m, -1);

    this.pVectMag = this.pVect.mag();

  }

​

  dist(_x, _y) {

    let Vxy = createVector(_x, _y - this.b);

    let dotProd = this.pVect.dot(Vxy);

    return abs(dotProd) / this.pVectMag;

  }

​

  get(_x, _y, _rgb = [0, 0, 0]) {

    let d = this.dist(_x, _y);

    let t = map(d, 0, 0.7 * width, 0, 1, true);

    let c = lerpColor(this.color, color(0), t).levels;

    return [

      min(_rgb[0] + c[0], 255),

      min(_rgb[1] + c[1], 255),

      min(_rgb[2] + c[2], 255),

    ];

  }

​

  draw() {

    strokeWeight(4);

    stroke(this.color);

    let y1 = this.m * width + this.b;

    line(0, this.b, width, y1);

  }

}

​

let squaresPerRow = 64;

let spacing;

let myLights = [];

​

function setup() {

  createCanvas(windowWidth, windowHeight);

​

  spacing = width / squaresPerRow;

​

  myLights.push(new LightLine(-1, width / 10, color(255, 0, 0)));

  myLights.push(new LightLine(-1, height, color(0, 255, 0)));

  myLights.push(new LightLine(-1, (19 / 10) * width, color(0, 0, 255)));

}

​

function draw() {

  background(0);

​

  for (ci = 0; ci < myLights.length; ci++) {

    myLights[ci].draw();

  }

​

  noStroke();

  for (let y = 0; y < height; y += spacing) {

    for (let x = 0; x < width; x += spacing) {

      let c = [0, 0, 0];

      for (let li = 0; li < myLights.length; li++) {

        c = myLights[li].get(x, y, c);

      }

      fill(c);

      rect(x, y, spacing + 1);

    }

  }

}

​

function mouseMoved() {

  let rise = height / 2 - mouseY;

  let run = width / 2 - mouseX;

​

  // 0.01 avoids division by zero

  let nm = rise / (run + 0.01);

  myLights[1].set(nm, mouseY - nm * mouseX);

}

​