// drawing 9 diagonal lines, with different line width
int s = 400;     // size of square canvas
void setup() { 
  size (s, s);
  stroke(255);    // lines in white 
}

void draw() {
  background(0);
  strokeWeight(4);
  line(0,0,s,s);
  strokeWeight(6);
  line(0, 40, s-40, s); 
  line(40, 0, s, s-40);  
  strokeWeight(8);
  line(0, 80, s-80, s); 
  line(80, 0, s, s-80);  
  strokeWeight(10);
  line(0, 120, s-120, s); 
  line(120, 0, s, s-120);
  strokeWeight(12);
  line(0, 160, s-160, s); 
  line(160, 0, s, s-160);  
}

void keyPressed() {
  save("image.jpg");
}