recursivePi.pde

PFont font;

void setup(){
  background(0);
  size(500,500);
  noLoop();
  // you can find this file in my LangtonAnt project
  // at https://github.com/Mizzlr/LangtonAnt
  // place FreeMonoBold.ttf in a directory named data
  // under the Parent directory recursivePi
  font = createFont("FreeMonoBold.ttf",24);
  textFont(font);
  textAlign(CENTER, CENTER);
}

void polygon(int sides){
   float step = radians(360.0/sides);
   float scale = 200;
   stroke(255);
   strokeWeight(2);
   line(0,height/2,width,height/2);
   line(width/2,0,width/2,height);
   pushMatrix();
   translate(width/2,height/2);
   
   stroke(0,0,255);
   noFill();
   ellipse(0,0,2*scale,2*scale);
   stroke(0,255,0);
   for (int i=0; i<sides; i++){
       float x1 = scale * cos(i*step);
       float x2 = scale * cos((i+1)*step);
       float y1 = scale * sin(i*step);
       float y2 = scale * sin((i+1)*step);
       line(x1,y1,x2,y2);
       fill(255,0,0);
       ellipse(x1,y1,10,10);
   }
   
   text("(1,0)", 200, 10);
   text("(-1,0)", -200, 10);
   text("(0,1)",0,-220);
   text("(0,-1)",0,210);
   text("(0,0)",0,0);
   popMatrix();
}

void draw(){   
   polygon(4);
   saveFrame("square.png");

   background(0);
   polygon(8);
   saveFrame("octagon.png");
   
   background(0);
   polygon(16);
   saveFrame("16-gon.png");
}