The artwork of the high-frequency wave belt

/**
 * Raining in My Heart.
 * draws vertical thin lines.
 *
 * @author @deconbatch
 * @version 0.1
 * @license GPL Version 3 http://www.gnu.org/licenses/
 * Processing 3.5.3
 * 2021.04.12
 */

void setup() {
  size(980, 980);
  colorMode(HSB, 360.0, 100.0, 100.0, 100.0);
  smooth();
  noLoop();
}

void draw() {
  
  int   imgMax    = 5;             // output image file number
  int   lineMax   = 9;             // horizontal line number
  float ampBase   = height * 0.05; // height of vertical thin lines
  float thetaDiv  = PI * 0.001;    // density of vertical thin lines
  float thetaMult = 20.0;          // changes pattern of vertical thin lines
  float thetaMax  = PI * width / 90.0;
  float marginY   = (height / lineMax) * 0.5;
  int   noiseBase = floor(random(100.0));

  PImage bg = getBackground(width, height);
  for (int imgCnt = 0; imgCnt < imgMax; imgCnt++) {

    noiseSeed(noiseBase + imgCnt);
    float phase   = random(TWO_PI);
    float hueBase = random(360.0);
    
    // draw background
    blendMode(BLEND);
    background(0.0, 0.0, 90.0, 100.0);
    image(bg, 0, 0);

    // draw foreground
    blendMode(SUBTRACT);
    noStroke();
    for (int lineCnt = 0; lineCnt < lineMax; lineCnt++) {
      float lineRatio = map(lineCnt, 0, lineMax, 0.0, 1.0);
      float direction = (lineCnt % 2 == 0) ? 1.0 : -1.0;

      beginShape();
      fill((hueBase + lineRatio * 360) % 360.0, 50.0, 30.0, 100.0);
      for (float theta = 0.0; theta < thetaMax; theta += thetaDiv) {
        float thetaRatio = map(theta, 0.0, thetaMax, 0.0, 1.0);

        float lineBase  = marginY + lineRatio * height;
        float amplitude = ampBase * (1.0 + lineRatio + noise(lineRatio, thetaRatio));
        float vibration = sin(customNoise(lineRatio * PI + theta * thetaMult) * PI + phase);

        float x = (0.5 * (1.0 + direction) - direction * thetaRatio) * width;
        float y = lineBase + amplitude * vibration;
        vertex(x, y);
      }
      endShape();

    }

    blendMode(BLEND);
    casing();
    saveFrame("frames/" + String.format("%04d", imgCnt) + ".png");

  }
  exit();
}

/**
 * getBackground : returns background image
 */
private PImage getBackground(int _w, int _h) {

  float div = min(_w, _h) * 0.01;
  
  PGraphics p = createGraphics(_w, _h);
  p.beginDraw();
  p.colorMode(HSB, 360, 100, 100, 100);
  p.background(0.0, 0.0, 100.0, 100.0);
  // matrix
  p.noFill();
  p.stroke(0.0, 0.0, 90.0, 100.0);
  p.strokeWeight(1.0);
  for (float x = 0; x < p.width; x += div) {
    p.line(x, 0, x, p.height);
  }
  for (float y = 0; y < p.height; y += div) {
    p.line(0, y, p.width, y);
  }
  p.endDraw();

  return p;
}

/**
 * casing : draw fancy casing
 */
private void casing() {

  float w = min(width, height) * 0.05;
  
  fill(0.0, 0.0, 0.0, 0.0);
  strokeWeight(w * 1.1);
  stroke(0.0, 0.0, 0.0, 100.0);
  rect(0.0, 0.0, width, height);
  strokeWeight(w);
  stroke(0.0, 0.0, 100.0, 100.0);
  rect(0.0, 0.0, width, height);
  noStroke();
  noFill();
  noStroke();
}

/**
 * customNoise : returns custom noise value
 */
private float customNoise(float value) {
  return sin(value * cos(value));
}


/*
Copyright (C) 2021- deconbatch

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>
*/