title: XNA 4.0 Glowing objects
body: <p>I am trying to achieve a simple task (or so I thought) in XNA 4.0. I have objects that need to glow (rendering and Gaussian blurring them and then adding them to the main scene). These objects can be at different depths so I will need to make sure that they are obscured by objects in front of them in the main scene. It's 3D.</p>
  
  <p>Because depth buffers cannot be re-used in XNA 4.0, I am having a hard time figuring out how I can achieve this? </p>
  
  <p>I can find no examples or tutorials or explanations of this process. The bloom post process example of XNA also does not do exactly what I need, as it post processes the entire scene.</p>
  
  <p>I know that I can preserve RenderTarget info by using PreserveContents, but it sounded like it was slow. Is there a way to achieve this without using PreserveContents?</p>
  
  <p>Any help would be appreciated.
  Thank you,
  Riaan.</p>