Open Brush, Open Blocks, Icosa Gallery•7mo ago

Transparent brushes aren't visible in passthrough mode on latest beta

Reported by @TheLastDegen here: https://discord.com/channels/783806589991780412/1238420358550257717/1238841455414345810 Confirmed by me.

15 Replies

andybakOP•7mo ago

@mikesky no great surprise but this is the offending commit: https://github.com/icosa-foundation/open-brush/pull/613/files#diff-4fa1d1641eac596f779411a63873fc5699b497b587a5f4414d66c279b97b6cbb every change looks pretty harmless apart from maybe this:

#if PASSTHROUGH_SUPPORTED
            OVRManager.eyeFovPremultipliedAlphaModeEnabled = false;
#endif

#if PASSTHROUGH_SUPPORTED
            OVRManager.eyeFovPremultipliedAlphaModeEnabled = false;
#endif

would you agree?

mikesky•7mo ago

Holy shit you’ve cracked it This is why oculus Passthrough “works” when all the others don’t quite

andybakOP•7mo ago

well. aside from all transparent brushes being invisible!

mikesky•7mo ago

Yes, that’s what happens in zapbox and pico! If we could find a way to do premult on other platforms it would be”fix” passthrough there

andybakOP•7mo ago

oh ffs. squash commits are again destroying my ability to do forensics and retrace my steps. remind me why deleting history is a good thing, again?

mikesky•7mo ago

Clean graph in Fork 😉

andybakOP•7mo ago

yeah. that seems like weak sauce to me

mikesky•7mo ago

There was other reasons, but I’ve forgotten them. @mikeage?

andybakOP•7mo ago

Can we at least not delete PR branches when we merge? Maybe move them to an attic/ prefix "folder" I'm still a bit confused. Should eyeFovPremultipliedAlphaModeEnabled be true or false?

mikesky•7mo ago

it should be true (which i'm guessing is the default, or do we set it elsewhere?), at least that's the quick way to get passthrough to work. I'm not sure if that's also asetting that we could find for openxr, zapbox, and pico, that would also achieve the same effect and get it working there too it's either that, or work out what else in our rendering isn't working. OR, now that we know that's how oculus 'fixes' it, work out what that's doing and emulate it elsewhere

andybakOP•7mo ago

yay. luckily on my mac, i don't do git fetch --prune so I've still got the passthrough branch to see when i added that line But it surely shouldn't rely on me forgetting to do that to be able to check back to see a specific commit message So - I added eyeFovPremultipliedAlphaModeEnabled when I did my first initial work on the passthrough brush - so I most likely found it in Meta tutorial on passthrough - that's what I think I was following initially. Let me see if I can find it.

mikeage•7mo ago

You should also be able to undelete, I believe, but I don't recall how offhand and I'm on my mobile

mikesky•7mo ago

    /// <summary>
    /// If premultipled alpha blending is used for the eye fov layer.
    /// Useful for changing how the eye fov layer blends with underlays.
    /// </summary>
    [HideInInspector]
    public static bool eyeFovPremultipliedAlphaModeEnabled
    {
        get { return OVRPlugin.eyeFovPremultipliedAlphaModeEnabled; }
        set { OVRPlugin.eyeFovPremultipliedAlphaModeEnabled = value; }
    }

    /// <summary>
    /// If premultipled alpha blending is used for the eye fov layer.
    /// Useful for changing how the eye fov layer blends with underlays.
    /// </summary>
    [HideInInspector]
    public static bool eyeFovPremultipliedAlphaModeEnabled
    {
        get { return OVRPlugin.eyeFovPremultipliedAlphaModeEnabled; }
        set { OVRPlugin.eyeFovPremultipliedAlphaModeEnabled = value; }
    }

it then disappears into OVRPlugin with no more info 😅 https://microsoft.github.io/Win2D/WinUI3/html/PremultipliedAlpha.htm for later

andybakOP•7mo ago

@mikesky Removing

#if PASSTHROUGH_SUPPORTED
            OVRManager.eyeFovPremultipliedAlphaModeEnabled = false;
#endif

#if PASSTHROUGH_SUPPORTED
            OVRManager.eyeFovPremultipliedAlphaModeEnabled = false;
#endif

seems to fix the transparent brushes and the passthrough brush still works. Still can't figure out where i got the idea that line was needed.

mikesky•7mo ago

Great to know! I see a few oculus samples turn it off, for whatever reason I’m looking to see if we can do this in a post process shader instead, then we could have it on all platforms It should be a really simple shader

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Transparent brushes aren't visible in passthrough mode on latest beta