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motorsep's avatar
motorsep
Member
9 years ago

[Gear VR] Mobile HDR kills performance - why ?

Just turning on mobile HDR in UE4 cuts fps (almost) in half. That's without having any post process effects on.

Why is that ? 

Thanks
bloom
HDR
Samsung Gear VR
Unreal Engine 4

3 Replies

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  • Norman3D's avatar
    Norman3D
    Expert Protege
    9 years ago
    I assume it consumes far more texture bandwith due to the amount of downsamples for the bloom effect for example. Wouldn't it benefit memory greatly to have one single downsample as opposed to having 3 downsamples? We don't seem to have much scalability with the current implementation.
  • motorsep's avatar
    motorsep
    Member
    8 years ago

    imperativity said:

    Hi,

    This is because HDR consumes far more texture bandwidth than the regular pipeline.


    Is there any way to have bloom/glow without HDR ? (and without faking it with transparent billboards, since it's performance taxing anyway)
  • motorsep's avatar
    motorsep
    Member
    8 years ago


    Bloom will require extra per-pixel work that will slow performance considerably on Gear VR. There are methods to fake this, but they generally require post effects or impostors and won't be fast.


    Wouldn't it be much faster to do "cheap" bloom as post process?

    Or something like this http://http.developer.nvidia.com/GPUGems/gpugems_ch21.html This kind of effect doesn't require HDR.