float hexRad, hexHeight;
float heightRatio;

void setup()
{
  heightRatio = sqrt(pow(0 - sin(2*2*PI/6), 2) + pow(1  - cos(2*2*PI/6), 2));
  size(500,500);
  hexHeight = width/2;
  hexRad = hexHeight / heightRatio;
      
  smooth();
  noLoop();
  colorMode(HSB, 1);
}

void drawHexagon(float cx, float cy, float r)
{
  beginShape(POLYGON);
  for (int i = 0; i < 6; ++i) 
  {
    float a = i*2*PI/6;
    vertex(cx+sin(a)*r,cy+cos(a)*r);
  }
  endShape();
}

void draw()
{
  background(0,0,0);
  float r = hexRad;
  float cx = hexHeight/2;
  float cy = hexRad;
  fill(0,.25,.75);
  drawHexagon(hexHeight/2, hexRad, r);
  fill(0,.25,.70);
  drawHexagon(3*hexHeight/2, hexRad, r);
  fill(0,.25,.65);
  drawHexagon(width/2, hexRad*2.5, r);
}

// save("hexagon.tiff");