title: Opengl: 2d HUD over 3D
body: <p>I have looked at some questions posted here on the matter and still cant work out why my 2d HUD appears but makes my 3d Rendered world disappear. </p>
  
  <p><strong>EDIT:</strong> It seems that the 2d scene is taking control of the entire screen so every now and then I can see the 3d scene glitching through the 2d scene. So even though I its only ment to be rendering a quad thats 10 x 10 pixels it renders this then blanks out the rest of the screen.</p>
  
  <pre><code>glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  gluPerspective(40.0,(GLdouble)x/(GLdouble)y,0.5,20.0);
  glMatrixMode(GL_MODELVIEW);
  glViewport(0,0,x,y);
  glClear(GL_COLOR_BUFFER_BIT);
  glLoadIdentity();
  glTranslatef(0.0,-0.5,-6.0);
  
  glPushMatrix();
  
  ..Draw some 3d stuff...
  
  glPopMatrix();
  // Start 2d
  glMatrixMode(GL_PROJECTION);
  glLoadIdentity();
  glOrtho(0, SCREEN_WIDTH, SCREEN_HEIGHT, 0, -1, 1);
  
  glMatrixMode(GL_MODELVIEW);
  glLoadIdentity();
  glColor3f(0.0f, 255.0f, 1.0f);
  glBegin(GL_QUADS);
      glVertex2f(0.0, 0.0);
      glVertex2f(10.0, 0.0);
      glVertex2f(10.0, 10.0);
      glVertex2f(0.0, 10.0);
  glEnd();
  </code></pre>
  
  <p>Then I swap buffers</p>
  
  <p>Here is the order of my code. Its like it makes the 3d space then makes the 2d space which in turn cancels out the 3d space.</p>