Harmonograph in Processing

harmonograph.pde

float d[] = new float[4];
float f[] = new float[4];
float p[] = new float[4];

float E = exp(1);

PVector current_pt;
PVector center;

void setup() {
  size(400, 400);
  background(255);
  
  d[0] = 0.02;
  d[1] = 0.0315;
  d[2] = 0.02;
  d[3] = 0.02;
  
  f[0] = 2;
  f[1] = 6;
  f[2] = 1.002;
  f[3] = 3;
  
  p[0] = PI/16;
  p[1] = 3*PI/2;
  p[2] = 13*PI/15;
  p[3] = PI;
  
  current_pt = new PVector(0,0);
  center = new PVector(200, 200);
  drawHarmonograph();
}

float partial(int i, float t) {
  return 100 * sin(t*f[i] + p[i]) * pow(E, -d[i]*t);
}

void drawHarmonograph() {
  stroke(0);
  beginShape();
  for (float t = 0; t < 100; t += 0.01) {    
    current_pt.x = partial(0, t) + partial(1, t);
    current_pt.y = partial(2, t) + partial(3, t);
    vertex(current_pt.x, current_pt.y);
    
  }
  translate(200, 200);
  rotate(radians(90));
  endShape();
}