title: Draw 2D thick arc using polygon in OpenGL
body: <p>I want to draw a thick Arc(something like colored segment of analog dial) using polygon. For that i have added vertices in polygon and its working fine for the outer circumference BUT its joining the ends for inner circumference(the concave side). </p>
  
  <p>The same logic works fine if I add those vertices in Line, but that creates an empty/non-filled arc.</p>
  
  <p>My logic of adding vertices is :</p>
  
  <pre><code>    for( float i = m_segmentVertex.size() - 1; i &lt; vCount; i++ )
          {
              float x1 = (m_segmentVertex[ i ].x ) * cosA - m_segmentVertex[ i ].y * sinA;
              float y1 = (m_segmentVertex[ i ].x ) * sinA + m_segmentVertex[ i ].y * cosA;
              addVertex( vec3( x1, y1, 0.0f ) );
          }
  </code></pre>