float x1, x2, x3, y1, y2, y3, h, u1, u2, v1, v2, a, c, cs, xs, ys;
float      hue=0;


void setup() {
  
  size(600, 600);
  smooth();
  background(0);

  cs = 80000.F;
  a = -2.F;
  c  = 26.5F;
  h  = 0.03F;
  x1 = 0.F;
  x2 = 1.F;
  x3 = 20.F;
  xs = 20;
  ys = 30;
}

void draw() {
  //background(0);
  //frameRate(30);

  y1 = x1 + h * (a)*(x1-x2);
  y2 = x2 + h * (-x1*x3+c*x1-x2);
  y3 = x3 + h * (x1*x2 - x3);

  u1 = width/2*(1+x1/xs);
  u2 = height/2*(1+x2/ys);
  v1 = width/2*(1+y1/xs);
  v2 = height/2*(1+y2/ys);

  stroke(255);

  line(u1, u2, v1, v2);


  x1 = y1; 
  x2 = y2; 
  x3 = y3;
}