title: Rotating a Spirte Rectangle 90 degrees doesn't repect aspect ratio in iOS
body: <p>am working in a OpenGL ES 2.0 game, in iOS platform using basically C++. And I wanted to implement both both portrait and landscape orientation doing a 90 degrees rotation.</p>
  
  <p>The problem I have is very simple. I have one sprite that is in one rectangle and if I do a rotation of 90 degrees and expected to see the same figure rotated.</p>
  
  <p>The problem I have is that is a noticeable difference in the figure, both in aspect ratio and size.</p>
  
  <p>In one orientation:
  8.4 cm x 5.0 cm</p>
  
  <p>The other:
  7.6 cm x 5.4 cm </p>
  
  <p>I wonder if it that is posible be casued by errors caused by float machine representation? Has someone had also that problem?</p>
  
  <p>In the first test I do:</p>
  
  <pre><code>glm::mat4 ProjModelViewMatrix = glm::ortho&lt;float&gt;(-1.0, +1.0, -1.5f, 1.5f);
  
  /// DRAW CODE
  </code></pre>
  
  <p>In the second test I ONLY add a rotation matrix:</p>
  
  <pre><code>glm::mat4 rotation = glm::rotate(glm::mat4(1.0), -PI_F / 2.0f, glm::vec3(0.0f,0.0f,1.0f));
  
  glm::mat4 ProjModelViewMatrix = glm::ortho&lt;float&gt;(-1.0, +1.0, -1.5f, 1.5f) * rotation;
  
  /// DRAW CODE
  </code></pre>
  
  <p>Just in case:
  ALL THE vertices are in the plane z=0.
  The sprite is mapped in a rectangle.</p>