title: glDrawRangeElements doesn't draw the chosen range
body: <p>I want to draw two cubes with a rectangle between them, so I stored vertices data into a vbo,then i created an ebo(Element Buffer Object) to avoid extra vertices(42 vs 12).
  I need to draw them separately, because I want the rectangle to reflect the up cube, doing stencil test and disabling the depth mask while drawing the rectangle.
  I thought I could draw the first cube with a glDrawElements call</p>
  
  <pre><code>glDrawElements(GL_TRIANGLES, 36, GL_UNSIGNED_INT, 0);
  </code></pre>
  
  <p>then, to draw the ractangle I'm trying to use glDrawRangeElements</p>
  
  <pre><code>glDrawRangeElements(GL_TRIANGLES, 36, 41, 6, GL_UNSIGNED_INT, 0);
  </code></pre>
  
  <p>but it is just drawing the base of the cube.</p>
  
  <p>For the last cube I am using the same draw call of the first, just inverting it in the z axis.</p>
  
  <p>I think i did something wrong with glDrawRangeElements parameters, because i tried doing just one call for the first cube and then the rectangle</p>
  
  <pre><code>glDrawElements(GL_TRIANGLES, 42, GL_UNSIGNED_INT, 0);
  </code></pre>
  
  <p>and it works.</p>
  
  <p>What's wrong with that glDrawRangeElements call?</p>
  
  <p>EDIT: I solved by not using a glDrawRangeElements call but a simple glDrawArrays call, rearranging the rectangle's vertices to draw two triangles;</p>