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Thormj's avatar
Thormj
Protege
2 months ago
Solved

Make GameObjects translucent to the Passthru?

For debugging and for a few specific bits (I want to make a Leia hologram in my scene), I'd love to have the gameobjects be translucent (alpha fine) to the passthru images.

If I "just set alpha," the gameobjects are transparent to themselves... but they still block all of the passthru...

So... is there a way to make a hologram in your living room that works?

  • Thormj's avatar
    Thormj
    7 days ago

    Found the solution.  Evidently the "UI screen" is special because it makes any material shader transparent to the background (how odd -- I guess it's because a canvas can be see-through, and it's seeing thru to passthru?)

    But if I change the material shaders to transparentShader ... it just works.  Sorry about the confusion; I've been playing in VR for a while, but Q3/Unity is way different than old-school OpenGL.

5 Replies

  • Thormj's avatar
    Thormj
    Protege
    7 days ago

    Found the solution.  Evidently the "UI screen" is special because it makes any material shader transparent to the background (how odd -- I guess it's because a canvas can be see-through, and it's seeing thru to passthru?)

    But if I change the material shaders to transparentShader ... it just works.  Sorry about the confusion; I've been playing in VR for a while, but Q3/Unity is way different than old-school OpenGL.

  • Thormj's avatar
    Thormj
    Protege
    2 months ago

    Err... weird.  It's only translucent if you have a UI Overlay screen in front of it (looking through a debug screen or a menu).  Otherwise it's solid.

    I tried putting the object on Layer 1 [TransparentFX] and no change.

    I tried putting the object on Layer 5 [UI Overlay] to match the menu...
    and it went invisible, so I change the opacity to 160 still completely invisible...
    changed opacity to 255...still invisible.

    So... I'm still lost...

  • Thormj's avatar
    Thormj
    Protege
    2 months ago

    Okay, the Passthru Building Block seems to have done the Underlay bit (though it says that that is "deprecated").

    I altered the shader Meta/Lit to Off with

            _ZWrite("__zw", Float) = 3.0 // auto | force enabled | force disabled -- was 1.0

    And that works well!

    Is there a reason not to do that for "the shader" (and let the material color translucency be "applicable to both in-game and reality" [keep it at opaque for things that should be opaque -- to both in-game and reality]), or should I make a special shader "Meta-Lit-Holo" and tell the material on the holo to use that?

     

  • Degly's avatar
    Degly
    Start Partner
    2 months ago

    Well, in Unity on Quest 3 you can’t make a mesh literally transparent to passthrough if Passthrough is in Overlay mode; regular alpha transparency still blocks the camera feed because of how the compositor orders layers.

    If you want a “hologram in your room” effect that blends with passthrough you have to:

    • Set your OVR Passthrough Layer to Underlay
    • Use a transparent/additive shader with ZWrite off on your Leia hologram mesh

    That way your object will blend into the passthrough instead of occluding it. If you need more information let us know!

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