int maxLength = 9999;
int idCount = 0;
SwirlParticle[] pt = new SwirlParticle[maxLength];

void setup() {
  size(400,400,P3D);
  frameRate(60);
  background(100);
  translate(width /2, 0, 0);
}

void draw() {
  background(100);

  if (mousePressed) {
    pt[idCount] = new SwirlParticle(idCount, mouseX, mouseY, 0);
    if (idCount < maxLength -1) { 
      idCount ++;
    }
  }
  for (int i = 0; i < idCount; i ++) {
    pt[i].rotatePos();
    if (i > 0) {
      stroke(map(pt[i].z,-width/2, width/2,100,255),100);
      line(pt[i-1].x + width/2, pt[i-1].y, pt[i-1].z,pt[i].x + width/2, pt[i].y, pt[i].z);
    }
  }
}

public class SwirlParticle {
  float x,y,z;
  float oridinalX;
  float angle;
  int col;
  
  SwirlParticle (int _id, float _x, float _y, float _z) {
   angle = 0;
   x = _x - width / 2;
   oridinalX = x;
   y = _y;
   z = _z;
   col = int(random(100));
  }
  
  public void rotatePos() {
    angle += 1;
    z = sin(radians(angle)) * oridinalX;
    x = cos(radians(angle)) * oridinalX;
  }
}