title: Draw the outlines of a 3D model with OpenGL ES
body: <p>I need to add this classic effect which consist in highlighting a 3D model by stroking the outlines, just like this for example (without the transparent gradiant, just a solid stroke) : </p>
  
  <p><a href="https://i.stack.imgur.com/cXS9z.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/cXS9z.jpg" alt="enter image description here"></a></p>
  
  <p>I found a way to do this <a href="http://www.flipcode.com/archives/Object_Outlining.shtml" rel="nofollow noreferrer">here</a> which seems pretty simple and easy to implement. The guy is playing with the stencil buffer to compute the model shape, then he's drawing the model using wireframes and the thickness of the lines is doing the job. 
  This is my problem, the wireframes. I'm using OpenGL ES 2.0, which means I can't use <code>glPolygonMode</code> to change the render mode to <em>GL_LINE</em>. </p>
  
  <p>And I'm stuck here, I can't find any simple alternative way to do it, the most relevant solution i found for the moment is to implement the wireframe rendering myself, which is clearly not the easiest solution. To draw my objects I'm using <code>glDrawElements</code> with <em>GL_TRIANGLES</em> as primitive, I tried to use <em>GL_TRIANGLE_STRIP</em> as primitive but the result is definetely not the right one.</p>
  
  <p>Any idea/trick to bypass the lack of <code>glPolygonMode</code> with OpenGL ES? Thanks in advance.</p>