title: What's wrong with using depth render buffer? OpenGL ES 2.0
body: <p>I use this code:</p>
  
  <pre><code>context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2];
  
      if (!context || ![EAGLContext setCurrentContext:context] || ![self loadShaders])
      {
          [self release];
          return nil;
      }
  
      glGenFramebuffers(1, &amp;defaultFramebuffer);
      glGenRenderbuffers(1, &amp;colorRenderbuffer);
      glGenRenderbuffers(1, &amp;depthRenderbuffer);
  
      glBindFramebuffer(GL_FRAMEBUFFER, defaultFramebuffer);
      glBindRenderbuffer(GL_RENDERBUFFER, colorRenderbuffer);
      glBindRenderbuffer(GL_RENDERBUFFER, depthRenderbuffer);
  
      glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_RENDERBUFFER, colorRenderbuffer);
      glFramebufferRenderbuffer(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_RENDERBUFFER, depthRenderbuffer);
  
      glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
  </code></pre>
  
  <p>But when I'm runing the application I see purple screen? What's wrong with this code?</p>