title: OpenGL FBO colour attachment shrinking
body: <p>I have an FBO with 4 frame buffer textures. These textures are 4 different sizes.</p>
  
  <ul>
  <li>texture 1 = 512 * 360 </li>
  <li>texture 2 = 256 * 180 </li>
  <li>texture 3 = 128 * 90</li>
  <li>texture 4 = 64 * 45</li>
  </ul>
  
  <p>The problem is that if texture 4 and texture 1 for example are attached using:</p>
  
  <pre><code>    glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT2, GL_TEXTURE_2D, bl_64, 0);
      glFramebufferTexture2D(GL_FRAMEBUFFER, GL_COLOR_ATTACHMENT0, GL_TEXTURE_2D, bl_128, 0);
  </code></pre>
  
  <p>When I draw to texture 1 the image on the texture only takes up the size of texture 4. </p>
  
  <pre><code> m_blurrFBO.DrawingBind();   
   glUniformSubroutinesuiv(GL_FRAGMENT_SHADER, 1, &amp;BlurrPass);  
   glViewport(0, 0, 512, 360);
   glDrawBuffer(GL_COLOR_ATTACHMENT0);
   DrawQuad();       
   FBO::UnbindDrawing();
  </code></pre>
  
  <p>The reason I'm using 4 different textures with different sizes is that I'm down sampling the same image 4 times each half the size as the last.</p>
  
  <p>The problem is the code has been tested on 5 different computers all with either AMD or NVIDIA cards and it works as expected. I have the up to date drivers for my nvidia gtx 550 is this a known problem ?</p>
  
  <p><a href="https://i.stack.imgur.com/qokpJ.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qokpJ.jpg" alt="The sunset should take up the full size of the screen"></a></p>