title: using glm::ortho projection in OpenGL
body: <p>I'm trying to simulate dropping a ball from 200 meters.  I know I have to convert the coordinates from -1.0, 1.0 to 0, 200.</p>
  
  <p>I draw my vertices of my ball like so:</p>
  
  <pre><code>for(int i=0; i &lt; NUM_VERTICES; i++)
  {
    GLfloat angle = 2*M_PI/NUM_VERTICES * i;
  
    GLfloat x = 10 * cos(angle);
    GLfloat y = 10 * sin(angle);
  
    vertices.push_back(x);
    vertices.push_back(y);
  }  
  </code></pre>
  
  <p>then I have an orthographic projection like so:</p>
  
  <pre><code>glm:mat4 projection;
  projection = glm::ortho(0.0f, 200.0f, 0.0f, 200.0f, 0.1f, 100.0f);
  </code></pre>
  
  <p>and a translation</p>
  
  <pre><code>glm::mat4 view;
  view = glm::translate(view, glm::vec3(100.0f, 200.0f, 0.0f));
  </code></pre>
  
  <p>but nothing appears in my viewport.</p>