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Thread: question about light prepass and msaa

  1. #1
    Intern Contributor
    Join Date
    Jun 2007
    Pittsburgh, Pa. USA

    question about light prepass and msaa

    Hey all, I am working on a light pre-pass renderer in gl 2.x currently and have some issues with MSAA.

    Near as I can figure it, I only really have a couple of choices.

    1. only msaa the forward pass, which means I don't gain early Z rejection from my pre-pass, as they have to use different depth buffers.

    2. do 3 passes
    pass 1 - burn depth only to msaa buffer
    - resolve depth to prepass FBO
    pass 2 - g buffer pre pass
    pass 3 - forward pass using pass 1 depth buffer.

    Any other ways I could go here?

    thanks for any input.
    Keith Z. Leonard
    Sword and Spirit, LLC.
    Schell Games, LLC.

  2. #2
    Junior Member Newbie
    Join Date
    Feb 2008

    Re: question about light prepass and msaa

    To the best of my knowledge, the only way to get "proper" MSAA with a light prepass renderer is to render and average the lighting using per-sample data. So you would need access to the samples for your normal and depth buffers.

    Insomniac games vaguely covers their implementation in the article on their "prelighting" system:

  3. #3
    Senior Member OpenGL Guru Dark Photon's Avatar
    Join Date
    Oct 2004

    Re: question about light prepass and msaa

    Also, see Engel's and the next talk here:

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