//let theta; //field angle [rad]

const layeralt = [100,200,300];

const freq = 0.003;

const strength = [400,-800,400];

let alpha1;

​

function setup() {

  theta = 20 * PI / 180;

  alpha1 = createSlider(-30, 30, -10);

  createCanvas(500, 500);

}

​

function draw() {

  let mean1 = [];

  background(255);

  textSize(16);

  translate(width / 2, height * 6 / 8);

  fill(0);

  noStroke();

  noFill();

  strokeWeight(2);

  stroke(0);

  line(-r, 0, r, 0);

  stroke(100);

  //line(-r, 0, -r - height * tan(theta), -height);

  //line(r, 0, r + height * tan(theta), -height);

  for (let ni = 0; ni < layeralt.length; ni++) {

    let alt = -layeralt[ni];

    strokeWeight(0.2);

    line(-width / 2, alt, width / 2, alt);

    strokeWeight(1);

    for (let mi = 0; mi < width; mi++) {

      line(-width / 2 + mi,

        alt + strength[ni] * (quad_func((mi-width/2) * freq) ),

        -width / 2 + mi + 1,

        alt + strength[ni] * (quad_func((mi + 1 - width/2) * freq)));

    }

  }

​

  // dir 1 

  let alpha = alpha1.value() * PI / 180;

  stroke(0, 0, 200);

  fill(0, 0, 200,10);

  beginShape();

  vertex(-r - height * tan(alpha), height);

  vertex(-r + height * tan(alpha), -height);

  vertex(r + height * tan(alpha), -height);

  vertex(r - height * tan(alpha), height);

  endShape(CLOSE);

  line(-r, 0, -r + height * tan(alpha), -height);

  line(r, 0, r + height * tan(alpha), -height);

  strokeWeight(2);

  for (let mi = 0; mi < width; mi++) {

    mean1.push(0);

    if (-width / 2 + mi < -r || -width / 2 + mi + 1 > r)

      continue;

    let sum1 = 0;

    let sum2 = 0;

    for (let ni = 0; ni < layeralt.length; ni++) {

      sum1 += strength[ni] * (quad_func((mi -width/2+ layeralt[ni] * tan(alpha)) * freq, 10 * ni) - 0.5);

      sum2 += strength[ni] * (quad_func((mi + 1 -width/2+ layeralt[ni] * tan(alpha)) * freq, 10 * ni) - 0.5);

    }

    mean1[mi] = sum1;

    line(-width / 2 + mi, sum1, -width / 2 + mi + 1, sum2);

  }

}

​

function quad_func(x){

  return (x)**3

}