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huge Gfx.ReadbackImage spikes when additively loading scenes - help!

Discussion in 'Global Illumination' started by allornothingJM, May 7, 2018.

  1. allornothingJM

    allornothingJM

    Joined:
    Feb 3, 2015
    Posts:
    20
    (Cross post from General Graphics)

    We additively load scenes for areas of the game, and been on a long journey of trying to iron out the hitches that occur when doing so. We've tracked down a few culprits, but this one has stumped me and I can't find any info online about it.

    When we stream in a scene, I get a massive spike of 110ms on Gfx.ReadbackImage, and also a massive spike in the renderer. There are no realtime probes active.



    What does the ReadbackImage do?

    Why does the renderer spike so much - is it rendering all geometry for a few frames before occlusion culling kicks in on those objects (hence it dipping back down again afterwards)?

    Any help on these topics would be much appreciated. I'm assuming there is a connection somehow but if it's two separate issues causing it then I'm happy to split threads.