title: i have created a circle from lines in opengl but it shows holes at outer edges
body: <p>I had drawn a circle in opengl using lines.But it shows a pattern of holes at outer edges.
  I want to fill this holes without reducing the radius and increasing the number of samples.
  This is my code:</p>
  
  <pre><code>void drawcirc(float xi,float yj,float r1,int num1)
  {
      glClear(GL_COLOR_BUFFER_BIT);
      //glBegin(GL_LINES);
      glVertex2f(0,0);
      for (int i=0;i&lt;=num1;i++)           
      {                       
      float theta=2.0f*3.141592f*float(i)/float(num1);
      float x1=r1*cosf(theta);
      float y1=r1*sinf(theta);
      glBegin(GL_LINES);
      glVertex2f(0,0);
      glVertex2f(xi+x1,yj+y1);
      glEnd();
      sleep(5000);
      glFlush();
      }
  }
  </code></pre>
  
  <p>then function call <code>drawcirc(0, 0, 0.6, 1250);</code></p>
  
  <p>what to do? this is my o/p with holes at outer edges.</p>
  
  <p><img src="https://i.stack.imgur.com/J5cvQ.png" alt="Sample Image"></p>