title: openGL(c) draw square
body: <p>i need to draw a square using c (openGL),
  i only have 1 coordinate which is the center of the square (lets say 0.5,0.5) and i need to draw a square ABCD with each side 0.2 length (AB,BC,CD,DA),
  I tried using the next function but it does not draw anything for some reson, </p>
  
  <pre><code>void drawSquare(double x1,double y1,double radius)
  {
      glColor3d(0,0,0);
      glBegin(GL_POLYGON);
  
      double locationX = x1;
      double locationY = x2;
      double r = radius;
  
      for(double i=0; i &lt;= 360 ; i+=0.1)
      {
          glVertex2d(locationX + radius*i, locationY + radius*i);
      }
  
      glEnd();
  }
  </code></pre>
  
  <p>can someone please tell me why its not working\point me to the right direction (i do not want to draw polygon with 4 coordinated normally, but with only 1 coordinate with a givven radius,
  thanks!</p>