Drawing array of curves from PVector

Processing Coding Questions
11

This is your code, minimally modified to just record pdf.
It creates copies of lines in the same location with geometric progression, like so:

image
image2067×1421 32.6 KB

(the amount of lines visualized)

import processing.pdf.*;

ArrayList<Particle> particles;

void setup() {
  size(640, 480);
  noFill();
  strokeWeight(2);
  particles = new ArrayList<Particle>();
  beginRecord(PDF, "vector.pdf"); 
}

void draw() {
  background(255);
  for(int i = particles.size() - 1; i >= 0; i--) {
    Particle p = particles.get(i);
    p.update();
    p.present();
  }
  
  if (keyPressed) { 
   exit();
   saveFrame();  
   endRecord();
  }
  
}

void mousePressed() {
  Particle p = new Particle(mouseX, mouseY);
  p.addForce(random(-1, 1), random(-1, 1));
  particles.add(p);
}

class Particle {
  PVector pos;
  PVector vel;
  PVector acc;
  ArrayList<PVector> history;
  int maxHistory;
  float maxWander;
  float maxSpeed;
  
  Particle(float x, float y) {
      this.pos = new PVector(x, y);
      this.vel = new PVector();
      this.acc = new PVector();
      this.history = new ArrayList<PVector>();
      this.history.add(this.pos.copy());
      this.maxHistory = 50;
      this.maxWander = 45 * (PI / 180);
      this.maxSpeed = 2;
  }
  
  void addForce(float fx, float fy) {
    this.acc.x += fx;
    this.acc.y += fy;
  }
  
  void update() {
    float heading = this.vel.heading();
    heading += random(-this.maxWander, this.maxWander);
    this.addForce(cos(heading), sin(heading));
    
    this.vel.add(this.acc);
    this.vel.limit(this.maxSpeed);
    this.acc.mult(0);
    this.pos.add(this.vel);
    
    float dist = PVector.dist(this.pos, this.history.get(this.history.size() - 1));
    if(dist > 5) {
      this.history.add(this.pos.copy());
      if(this.history.size() > this.maxHistory) {
        this.history.remove(0);
      }
    }
  }
  
  void present() {    
    float k = (float)this.history.size();
    for(int i = 1; i < this.history.size(); i++) {
      stroke(0, (i / k) * 255);
      PVector p1 = this.history.get(i - 1);
      PVector p2 = this.history.get(i);
      line(p1.x, p1.y, p2.x, p2.y);
    }     
  }
}